Yup, my father taught me this trick in the early 70’s except he used full strength white vinegar. It took a few days but worked quite well. He also showed me how to forge a worn out file into flint steel to use for starting campfires. Miss him every day.
Thank you eho you have just saved me a lot of notes on buying more files. Files are in use pretty much every week here for all kinds of tools and chains of saws. These things don't last long now and of course they can cost one lots. Re cleaning them will be helpful to me and my pocket in NZ.
I was given a bunch of old files and decided that I had nothing to lose by soaking them in acid. In my case I used muriatic acid and let each file soak for about ten minutes. I then neutralized the files in the baking soda solution. Some clearly cut better after the etching and some didn't. It depends on what you start off with. And yes, the acid cleans the files beautifully. So for all you trolls who have made negative comments, you have several options: 1) discard all your dull files and buy new ones; 2) Have your dull files hydro-honed where you'll pay to ship them plus the cost of the process; and 3) Try the technique described in this video. It all depends on what your expectations are.
You've confirmed what I thought, it depends on what you start off with. A real worn file won't improve from this methode, but a file that is just dirty and/or corroded might. Nice tip, think I do step 3 first to decide which files to discard (and to reforge into something else). Think I'll just use vinigar and let it soak longer though.
I was always taught that keeping files in a drawer where they could rub together was the worst possible thing you could do to it. I always keep my files separate.
There's a reason they're shipped wrapped in waxed paper... each file in its own pocket. Rubbing files on each other is how you get these nice bright curved lines on them.
File steel is some of the hardest steel commonly available. By keeping files in contact with one another does not necessarily mean disastrous results ensue. File steel also has "toughness" which means that some abuse is normal. The way files are dulled is through pressure and extreme conditions such as exposure to water and other corrosive chemicals not through storage and random incidental contact with each other.
Yeah i was thinking, I've never heard this before. Like you i was taught the same thing. Don't rub them against each other and don't let them rub anything but what you are trying to file and only in the right direction.
@Steel and Tree Design the key to making a joke, is making it obvious. There is no indication of this being a joke. Most average people getting into working with their hands would take this video seriously and be mislead. Kind of a dick move kinda video if you ask me. Just makes this dude look like a fool.
I've just done this with all my files - everything from fine needle files right up to coarse rasps, and I'm blown away by how well it works. That's over 40 files I would otherwise have tossed - in NZ about $2k worth (as some were fairly specialized) One thing I would warn y'all of is being careful to neutralize afterwards, and then CLEAN the acidic patina out from between the teeth - otherwise they'll rust up real quick. As a jeweller I'm fortunate to own an ultrasonic bath, which was perfect for this job :) And BTW yes - they were all clean beforehand - just blunt. In fact some came up sharper than new.
As a retired engineer with a small workshop my files are very important to me, rather than use a file card (which has steel pins) I use a brass bristled brush so it doesn't tend to blunt the file. When I was at school some fifty years ago, the metalwork teacher used this acid method to restore files. If you buy new files always keep one face unused for.use on brass, even files slightly worn files will not cut brass very well. I engrave the word 'Brass' on the uncut part of the file to remind me.
That's a good suggestion regarding the brass. A jeweler I know has separate files for gold, platinum, nickle and steel. Mixing flecks of metal between jobs would completely ruin the product.
I once made brass filings to mix with epoxy for a pottery repair. I spent hours filing a brass pipe fitting to make those filings. It never really occurred to me that brass would be harder to file but that project made that fact very real.
A file card will not blunten a file, the bristles do not engage with the file teeth, and are soft so even if they do (bent bristle etc) it don’t matter
I've heard that this was possible, but you gave us a great demo complete with safety warnings. It was a very good use of my time. I appreciate your good work.
machinists also do this when using a smooth file to draw file a work piece to help reduce/eliminate clogging and pinning which can damage the surface finish.
Absolutely. If you are filing aluminum and other soft metal that are sure to clog the file, loading it up first with chalk is your best bet. Been doing it for decades.
nice! and much faster than they way i sharpen my files (one tooth at a time). esp liked the copper pipe cleaner. i use wood, but I'll have to try copper on the stubborn ones. thanks!
Incredible! Wonderful and useful! I was always taught at school to NOT put files together where they could dull each other - but to chalk them (although nobody ever showed me what kind of chalk to use or how to use it!!) and wrap them separately in paper or cardboard. We were told as an alternative to stand them in a block of wood with appropriate holes drilled in it, and placed where no metal would bang against them.
David Chadwick explained that he used French Chalk on files to stop them from loading up. In England, French chalk is another name for what I call soapstone here in the states. It works great. The soap stone is slightly slippery and stays in the teeth of the file. Chips don't stick to it.
That is exactly what I was taught and still practice that to this day! I do have a handful of dull files and will try the method demonstrated in the video. Worst case, I'll make knives out of them.
@@OldSneelock watched an old instructional video on filing the other day and they were talking about French Chalk especially on the late stage of finishing the work piece. this is the video: th-cam.com/video/P5Kp0WEGawY/w-d-xo.htmlsi=B77XjDmer3Es4XIw
Wow, this is great! I have a bunch of old machinists files that were my Dad’s, that are all dull but I didn’t have the heart to throw away. This will rescue them, thanks so much!
I've been hand filing saw teeth for 35 years or so and I've gone through many files. As such I've been using this method to save a few bucks. It really works.
0:56 Before I was allowed to be enrolled and studying at the High School in Aachen to become an Electrical Engineer, I had to absolve an internship, learning to weld, filing, sawing, etc. The studies did not work out but what I learnt in the training workshop proved priceless throughout the next 55 years and still do.
I can even tell by the difference in sound pitches or notes the file produced before and after the process that you actually did a good job on that file, thanks for sharing this tip
I have to say we all should be listening to the old timers more we would all have more knowledge . Those old guys and gals have made my jobs a little bit easier , thanks dude.
I use a very similar method on my files, but use a 100% salinity table salt brine and DC current to electo etch a few microns off the outer surface. Microscopic inspection before and after shows a clean sharp edge where they had been rough and rounding.
You would be better to use washing soda as the electrolyte as it is less corrosive and not hygroscopic if you fail to rinse some of it off. It also does not release chlorine during the reaction.
Thanks! After watching the video and realizing what this process was accomplishing, I immediately wondered if using current to blast away the surface would also work! Although I appreciate this is 2yrs layer, I have some questions, if you happen to get this notification... - What did you use for the other terminal, and how far away? - What power source did you use? (and at what voltage, if it is a variable source?)
@@DUKE_of_RAMBLE I used the file for the anode (-) and an old bolt for the cathode (+). I was just using an old 120 volt ac to low amperage 12v dc transformer like you would use to power a cordless phone base. An adjustable power supply would be nice but I did plenty of electro etching and black oxide coating with that basic setup. ( for oxide coating just reverse the polarity to deposit iron from the sacrificial anode onto the part you're coating.)
@@justindunlap1235 Awesome! Thanks. So if you don't mind, last 3 questions (hopefully lol) *Duration of time left in there to etch?* Based on whatever length file you were sharpening, and I can try to extrapolate from there to fit my file lengths. *Was it a long cathode (bolt) or completely random, and approx what distance from the file?* In my (limited) experience, the length of each node, and even their angles relative to each other, drastically effects the path the current takes (electricity liking _"path of least resistance"_ and all that). So a short cathode, even if dangled mid-way, would end up doing more work nearest to it - potentially leaving the file with low spots where more metal was liberated from it. *Size of container needed (or that you used)?* Thanks again! 🤘✌️
I would use a plastic container approximately 14x18x4 inches with a very long bolt, long enough to touch the bottom and still protrude from the solution. I noticed I would get the most consistent results when the cathode and anode were placed vertically at opposite ends of the tank, as for duration it's not more than a few (3-5) minutes to get a decent etch on a 12 inch file ,depending on the power supply used, I've tried using a 12v battery charger before and was amazed at how fast it would etch, for oxide coating the longer you leave it the thicker the coating will be.
i was skeptical that it was going to do much, my files are pretty old and used hard, i wasnt amazed , i was absolutely blown away, they are like new ,it worked wicked awesome, mind bottling !
unclogging or sharpening this is something lots of people did not know how to do and will help them with there files working again and its very easy...nice job.
Dale, Thanks for this helpful trick! This afternoon, I've been working on restoring about 8-10 files that I thought were total junk... just tried the first 3 that I took out of the acid bath, and they cut like a new file! I used Muriatic Acid (hydrochloric acid) instead of sulfuric. Probably the best tip in this video is to use a piece of copper pipe to make a file scraper... it works better than any file card ever created for cleaning the file... and is probably responsible for 75% of the success of this method. Thanks again, I've now got about 10 more "new" files for the shop that were destined for the scrap bucket!
I learned the same trick as an apprentice, the only difference was that it was a 9% sulphuric acid mix and it was left in the solution for 2 hours. Afterwards, you put the file in cold water and agitated for a bit. It worked well. I never did it a second time but I remember being told it only worked the once. Good post, thanks.
yes, I am a swordsmith, and I really go through files (filing spring-hard steel a lot). copper and wood both work. For small files, get a popsicle stick to clean them out. Same trick.
Am pattern welding files into knives with high nickel saw blades for contrast put into nitric to reveal. I imagine the nitric acid(dilute) would work nicely and quickly for file sharpening.
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1: never heard of that one with the files self-sharpening in the drawer. 2: That drain cleaner is water, detergent and some acid... you need concentrated sulfuric acid to create that exothermic reaction and the concentrated sulfuric acid looks like yellowish/brown oil or thin honey. 3: removing rust and slightly etching the file to sharpen it with acid - pure genius! Onestly! Thanks for sharing!
I always use citric acid, it works just as well but is less bad for the environment. Also, I use a 40volt dc power supply so as to speed up the process like in Electro polishing, the electricity makes more metal erode of the planes than of the points and the file becomes even sharper. After I use the citric acid I bring it to a recycling company, fresh citric acid you can pour down the drain, it will be deluded and become harmless. Citric acid that is used with metal can be full of chrome 6 and 7 so recycle it responsibly. The acid I use comes from citrisurf(brand name) ps. great video not many people know this trick and throw their files away
This is electrochemical machining, and probably much superior. Does some iron plate out on the Cathode? Is the cathode lead or stainless or does it matter? I think this is the right path and hope you will publish something.
How do you connect the power supply? I tried something similar with a 12 volt battery charger and just fried it. Didn’t know who to ask but hopefully you can explain the correct method?
Electroetching will be faster *but* the tips of the file teeth have a higher electrical potential and will erode faster and as a result, the files won't be as sharp, it may even dull the file more, depending on the electrolyte, voltage and current. That what the process of electropolishing does, it removes the high points on a surface to produce the polish. There are shops that specialize in electro deburring.
An old machinist taught me many years ago about using a soft piece of metal to clean a file. I’ve still got a piece of brass shim shaped like an L that I use. I’ve used aluminum, it works fine. Had a piece of brass dar stock that I had used for a punch pin that had mushroomed the head, that mushroomed head worked well. Obviously, the copper you used here does the trick. I’ve never used chemicals to clean a file, but I’ve not ever had a rusty one. Well done and thanks for the video.
This is a time honored method, and it does help to improve the files cutting ability. The acid etches the file steel. This method does have its limitations though. For example, files that have been abused, stored or used improperly. All of which are a very common issue. I have seen many a file just tossed in a drawer or bin with other hardened steel tools and files. I have also seen files used with saw like, or in a scrubbing/sanding motion. This will rapidly round/roll the file teeth over. Even milder (softer) steels can have this effect on a file if it occurs often enough. Or they attempt to file on steel that has been work hardened, think, an edged tool (such as an axe) that has been used to strike something hard such as stone. This high speed impact crushes the edge of the tool, which causes the molecules at the site of the impact to become heated and compressed. After the impact the molecules at the site of the impact rapidly cool and often become harder than the file being used to resharpen the edged tool. This sharpening attempt literally rounds or rolls the fine edges of the file over, thus, destroying the cutting edge of the file. Files can only cut materials softer than the file itself. If the steel is too hard for the file, the steel must be carefully ground to remove the work hardened steel. Any action that causes a file's steel to become hot will soften the steel of a file, making the file useless as a file. To me all of these forms of file abuse are indications of clueless and unskilled workers (aka: greenhorns). Or... people that just don't give a damn.
In an old book I have re sharpening files it says: Immerse file in acid for a short time. Then pass lightly a piece of cork along it to remove acid from the top of the teeth. Immerse again. Pass the cork and repeat as necessary. What is being done is actually to not let the acid eat away the top of the teeth but only the valleys. Never tried it meself.
That is not very rational thinking. First the valleys are not dull the teeth are. Second the second you dip the file into the acid it is back working on the teeth.
@@thinkfirst6431 Actualy, it is very rational. You are just not getting it. Luckily science does not give a rip and it just keeps on doing what it does even though some of us are just a little to invested in cognitive dissonance to understand it. If you really refuse to accept proven concepts then just send all your dull tools over my way. I get a kick out of bringing old tools back to life. Save a grip of cheddar in the process.
@@edstimator1 Actually it is not very rational. no one ever cut anything with the valley of a file unless it was ground down into a knife. The acid is doing the work the cork might at best be wiping some of the sludge off of the top of the teeth speeding up the process an amount not worth the effort. The cork is too soft to effect the metal and would absorb some of the acid so that your just rubbing the metal with a soft material soaked in acid. The acid is what is doing the work. The acid eats the metal at a constant rate over all of the file. The reason that it works is that the tops of the teeth are worn at different rates. The very thin tops are dissolved at a "faster" rate than the thicker worn parts of the file so that when the worn parts of the teeth approach a sharp edge again the thinner parts and the thicker parts join in a "sharper edge in roughly the same time making the surface of the tooth more or less "sharp". No one gives a crap how deep the valley is, only how sharp the cutting edge of the file is. The acid dip only works as long as the hardness of the file is uniform in depth. If the hardness varies so will the chemical sharping. Acid dip works, the cork is just BS.
Theoretically speaking, using your files correctly should keep them sharp... this is a great instructional on how to clean them up, which is also necessary!
When you get new files, keep them separated and dry where they won't bump into anything. I have my own handmade rack I keep them in, much like a knife block. Card your files often and keep them chalked. Use the proper file for the job at hand. If you take good care of your files, you won't have to resort to dipping them in acid, which only works for a little while (the file will quickly dull again) with diminishing returns. For all this trouble, you might as well just purchase a sharp new file and take good care of it rather than handling caustic chemicals.
We were taught to use blackboard chalk when filing , this stops the teeth from becoming clogged with metal filings . Regular brushing & reapplication of chalk to the teeth while in use & storing of files protected in cloth help make a file stay sharp for a very long time
Thanks for sharing. As Michel Nadon said earlier, it would be nice to have visual proof of the effect of acid etching on the cutting edges of the file. In theory, what you are promoting might work if the acid etches all surfaces equally and a round tip will become a sharp tip as a consequence. However, I think we need to see this happening to be convinced, My feeling is that sharp edges will be strongly attacked by the acid and come out rounded.
A similar process I tried does sharpen dull files. Whether the system used here sharpens them depends, I suppose, on how badly dulled they are. The copper cleaning tool is a great tip. I used muriatic acid from a masonry supply house and vessels made of PVC sewer pipe with an end cap cemented in place. I left the files in for many hours which ate away a lot of steel, too much in some cases. Worse, the fumes seemed to alter the chemistry of my shop. Here in a dry part of the country I'd never had rusted tools. Since the acid etch everything wants to rust so do it outdoors.
This a common problem with hydrochloride (HCl or muriatic) acid - even the fumes from an imperfectly tightened lid on the HCl bottle can cause corrosion through your shop - best to store strong acids in their own steel (sacrificial) cabinet with a bunch of seashells in it.
Good video, I've never heard of using acid. I keep my files clean and not banging around but this will keep them more usable longer, then I'll make knives or tool bits out of them, great steel.
I have a drawer full of old files that are VERY dull but being a pack rat I didn't have the heart to scrap them. ( always thinking I could do something with them)... Now I have a mission. when I get a chance I will try your idea out. thanks for your video and knowledge It's amazing that if you get a chance to spend some time with your elders what they can teach you. They didn't get old sitting under a tree. I am a retired auto tech and I have 4 sons. when ever we are working something and we are stuck on how to fix the problem most of the time I will come up with a plan on how to get around the problem. Its to the point now that they teach me things. When I do and it works I just tell them that I "Read it in a book once" The book is----" life experience. " their book is growing also.
try this, take one random file and leave it soaking in white vinegar for a couple days. compare it to the experiment above. i'm curious to the results. :) ive used vinegar to achieve the exact same results as this vid so Id appreciate a 3rd party opinion.. thanks Greg
Lol, I buy a lot of garage sale files to make tooling and knives out of, but after cleaning they work too well as files. If I make a knife or something out of one of them - seems like I always find a use for the file I just destroyed.
That was awesome!!! I have so many of them that won’t work anymore and always wondered if we even possible to re sharpen files but you came to the rescue!!!! Thank you! ❤❤❤❤
@@davidwrighton3914 You are right. Files are too hard and brittle for lathe bits. But they might work if you tempered them to make them just a little tougher and less brittle.
A soft aluminium strip, run across the full in the same direction as the cut in the surface will form teeth and clean the old filings out allowing it to cut again . A blunt file is usually just a clogged up file . If it's dull , you cannot sharpen it
Yup - it's known as 'chemical sharpening'. Even etching of the tooth surfaces leaves them with a sharp edge. Cleaning the file first is essential, however, as gunk in the teeth will protect the faces, meaning you'd only etch the tips, rounding off and blunting the file.
People arguing whether or not this actually sharpens vs. cleaning, have forgotten all about how we used to "acid dip" our muscle car bodies to make them lighter. Acid evenly removes metal from all exposed surfaces. That includes points, ridges and valleys. Let's picture ridges and valleys of a file. If the file is dull, the ridge will be a mini plateau. If you acid etch, the sides of the ridges will eventually wear away until the plateau becomes a thin ridge again. Thus, making a new point or ridge. Likewise, the valleys get deeper. If you leave it in solution too long, you'll end up with flat bar. And if the file isn't extremely clean and wire brushed, all the etching action is happening on the left over crud, and not much on the actual file.
@@jerryking1434 fukkin idiot ... You turn it into a knife. It's called recycling. You cannot sharpen any file... unless you have equipment to cut such fine, angled, and uniform angles... Or have you mastered Nicholson ??
Kenneth Kustren your either super slow on the uptake and can't process humor, or you're just a super big asshole that wants to spread his asshole comments around and put people down. William Miller was making a fucking joke, and yeah wasn't the funniest but it made me laugh. You need to get some help with that because it's going to end up destroying you one way or another.
William Miller I've made several knives from old files myself. Just remember to do both heat treatments so they aren't so brittle then to put temper back into the file.
It dissolves the surface which brings the teeth back to a sharper point, if you try it yourself you’ll see what I mean, if the teeth were rounded before, the two intersecting planes of the tooth dissolve evenly bringing the two planes closer together and therefore deleting the rounded tips of the teeth, I agree, if he has the close-up cameras ability to show it, it would be helpful to explain using the visual aid to show this effect. Even a drawing would be helpful
@@b2manufacturing the rounded cutting edge will as fast resolve as the surfaces. I don't think it will make it sharper, but the proces will clean it more up, so the teeth will become more corse regarding the high and lows of the teeth, so it feels like it's sharper again. Better buy a new file, they are not that expensive.
Thanks for sharing the old timers instructions with us. I just love this sort of thing, because if you didn’t know anyone who knew how to do this…then you didn’t either.
I have been doing this for many, many years, but I now use a piece of 2" pvc drainage pipe, capped at one end, so I can fill it to cover the whole of the cutting parts of the files!
@@BuildSomthingCool Can you also teach me how to sharpen each file tooth too please. My 5th and 7th tooth are blunt and it's making a funny sound, kinda like it's out of tune.
The copper tube part is one of the most important steps in cleaning a file and you didn’t even barely mention it. When you run the copper flattened tube over your file, the softness of the copper allows it to form down into the teeth of your file and clean it. This is one of the most important steps. You need to elaborate on that and how it works if you ever make another one of these.
I heard about this trick many years ago from an old time sharpener. He also used files for a living to sharpen very fine cutlery. He said they would be ok but not great. I guess i will have to try it for myself.
the solubility of sodium bicarbonate is around 100 g/L at room temp. So if you have a water volume of ~4 L, like it looks like you do, you would need right around a pound of baking soda before it reaches its saturation point (Ksp). Just letting you know.
Btw, ego in their right mind would think that storing files I drawer, and letting them rub together, would sharpen them? That makes no sense whatsoever. It would do the opposite.
Do this outside. The fumes from the acid are HIGHLY CORROSIVE do not do this process inside. The fumes from the acid will settle on anything metal and corrode the surface and you will have rusty tools or machinery. I do decorative acid etching and found this out the hard way when i did some etching under a cabinet that held all of my taps and drill bits. It corrodes the protective coating and made everything rust.
In a similar way I found that bleach vapors will rust any steel that they touch. My binoculars were stored in a cabinet. The laundry soap was moved to a lower shelf in that same cabinet so it would be easier to reach. When I found my binoculars that fall it took quite a bit to clean off the surface rust. Good thing my guns weren't in the same cabinet.
Big Dan No slam intended Big Dan. I just know if I ever used the toilet for sharpening files I would have to have a food taster for the rest of my life. Despite that it has it's merits. Fresh water anytime you need it. Self rinsing. Porcelain bowl that isn't bothered by acid. If it wasn't for winter hitting Michigan 6 months out of the year I'd be seriously thinking of installing one in the shop for just such uses. :-)
A clear explanation of this process and several similar metods can be found at page 235 of Workshop Receipts: For Manufacturers and Scientific Amateurs, Volume 2. It's available free from Google books.
Happy to. When I first learned about the process from Jim Thompson on the Old Tools Mailing List I was a bit skeptical. It sounded too good to be true. Jim had never steered me wrong so I tried it. It worked. I had some growing pains learning how long to leave the files in the bath. A couple of Swiss cheese files convinced me that forgetting them was a sure route to failure. :-) When I knew it worked and had finalized the process I decided to share it. I expected a hundred or so people that I regularly corresponded with on the list would be interested. Little did I know it would be one of the most viewed videos on my channel. Then along comes Colin Riley on your channel. Next thing I know your video is at a quarter million views and climbing. My video is at sixty thousand and climbing, and my channel has passed three quarters of a million views overall. Colin may be a pain but I really appreciate him starting the whole "It's only cleaning" meme.
i was taught that if a flie dose not cut clean it with a file card . but how dose acid which eats /erodes material actually sharpen . as a file is hardened you would need a diamond sharpener more important never use a file with out a handle. you are showing your true professionalism please correct me if im wrong so i can throw all my qualifications in the bin
If you're the type that always grabs the file brush when they grab a file, you may never need to do anything further. This is for when the rust and gunk build up so much that the file card won't cut it, (while a file brush removes chips well, it doesn't do such a great job of polishing the grooves). As soon as you remove the oxidation from steel, it comes back. If the rust gets to the point the brush can only remove the rust from the very edge you'll find yourself using the brush more often. Just the act of using the file helps to clean the edge. Like I said, using the brush often means you might never have a problem. Rusty garage sale files? They need more than a brushing. The deep groove in a file is just as important as the cutting edge - the chips need a place to go or they act like bearings - not good if they are full of rust.
During use the tips of the file teeth wear away. That is normal wear. As the file wears it begins to skid over the metal rather than biting in. At that point it is a viable candidate for either hydro-honing or acid etch sharpening. If the file is abused, banged around in a box full of tools, run against hardened steel, or dropped so that the teeth are broken and chipped they are not candidates for hydro-honing but only because of cost. They can still be acid etched. Without shipping costs and the time involved, if you are able to save only one in three it's a good deal. Perhaps most of the file is okay with just one side screwed up, or one end. With no appreciable cost involved, what do you have to lose? If the file is a little rusty or dirty, use a file card or perhaps a soft steel bar, like I use in my file cleaning video, to scrape the rust and dirt out of the teeth. Something I haven't noticed in these discussions is any comments on pinning. It's not the topic of the video but if we talk about cleaning, as nearly every post has mentioned, then describing the things that create the need for cleaning should be defined. Pinning is when the gullet between the teeth becomes filled and stops the tooth's cutting edge from contacting the surface. If you are having this problem then cleaning will be an endless effort. It is caused by the teeth being too fine for the chip load. Go to a larger file with bigger teeth.
Duncan Harris: I think one reason to throw your qualifications in the bin is that they should have taught you to look into statements/ processes offered on this video before posting negative statements of your own, just try it, then you can post a valid comment! (I would have thought that anyone with any kind of qualification would not be an armchair critic).
tell me where the shapening comes in ? as pointed there is an etching effect am i not the only one question. but as a professional my kit is looked after ( may be a snob having separate compartment for tools so they don't get damaged ) when you have worked in motorsports doing silly hours come back an then call me an arm chair critic
Duncan Harris As soon as you clean steel it starts to oxidize. An oxidized edge isn't as sharp as a clean edge. Whether we sharpen the edge by rubbing, scraping, grinding, or chemically treating the oxidation away - if the edge is sharper as a result we have sharpened it. Clean tools are always sharper than rusty tools, even if the difference is negligible. It doesn't matter how organized and clean you keep your tools, when it comes to cutting edges made of steel, they will cease to work at an optimum level the longer they are exposed to oxygen. Leave a file in the tool box for 5 years, and even if it was spotless when you put it away, it's going to take some work to clean up. Will it need an acid bath? Maybe not - but if somehow sat in water a couple of those winters it will - and a file brush won't be the tool to use. Don't worry about it too much. I'm sure somebody out there has a tank hooked up to their toolbox to keep it flooded with nitrogen, I don't.
You forgot to mention that before the acid wash you must clean and completely degrease the file before dipping it in acid! Acid will not touch metal that is oily or greasy.
Mostly it does not, oil needs to be removed with a caustic solution or soap, acid will mix with water but as it is mixed with water it will not mix with oil.
The 1k thumbs down is rather humurous, because they have no clue, my grandfather, a master craftsman & machinist showed me this almost 40 years ago, great to see basically the same process shown, I was throwing some what I thought was junk files away, he asked what I was doing, and showed me essentially the same thing, the only difference is he used diluted muriatic acid, & put them in 3" pvc with one end glued & capped, the other end just a slip on cap with a small vent hole, left them overnight, cutting edge up neutralized them with baking soda & they were razor sharp 👍
But....but...but...the master craftsmen of earlier time didn't have Google to prove???? That's right they became master craftsmen through years of work, experience, and training. This a simple process that has worked for many many decades before I was taught this method back in the early 70's. Believe it or not all you Nay Sayers it still works. It's really a simple process....quit over-analyzing it. If you want to pick the fly shit out of the pepper at least know what the fly shit looks like.
Looks like it works OK. I would be interested to see what a high powered microscope on the tooth profile on the file looked like before and after. If it just cleans the file, it would be useful enough but if the effect of the acidic bath alters the tooth profile it may be even better.
I belive is called chemicaly sharpening, is a method used to sharp fising needles, razor blades, because it takes less time and is cheaper than going through multimple grits of sanding materials. They just sharp them up to a point, then dip them in accid, this will disolve the steel and leave the edges as sharp as steel can be. I wouldn't say is better because it also weakens the teeths of a file, and if you do this multimple times, i would say more than two times, it will affect the flatness of the file and it will eat the teeths. Is good method, i never tried it, but i played with accid to remoe some rust. For old files, is better to give this treatment then throw it away. And old files can be turned into other kind of tools, such as chisel, or marking knives.
A good source for tall, skinny containers for this use, chemical derusting, etc. are flower vases. Keep an eye out at yard sales, they can be had for pennies.
Hi Dale, nice tip, but using the file without a handle... you were specific about safety with acid & wearing protective gear but not mentioning file handle ... tut, tut,
I have done this using plain cheap white vinegar. Leave the file in the vinegar 10 or 12 hours then rinse well and oil it or use some WD40. I know all of the anti- WD40 stuff but it works for me so save your keyboaed
Laurence Rilling I doubt it, I have heard a couple people saying it will work, similar to how you can "sharpen" knives by running their edges against each other.
@@danielnapast4955 he was definitely joking, problem is that this joke has weaseled its way into the shops of some people who are unaware and have gone on to repeat it. Whether they said it as a joke or not it was passed along so often that at some point certain people began to believe it. It is always said sarcastically by some old salt claiming that he sharpens his files by throwing them in the drawer with the others and they sharpen each other, meaning, ...he doesn't sharpen his files. I would bet that some new blood heard it and could not identify the tone. Same guy that spends 6 hours of his shift looking for the blinker fluid and can't figure out why everyone is giggling under their breathe.
the file is mechanically cleaned to get the swarf out of the teeth, and a step not included is a detergent bath and scrub, to clean off any oils that may be on the file. Acid etches or dissolves the surface of the metal of the file...remember that each "tooth" has an upper and a lower surface and these are etched or dissolved. What is left behind is a somewhat sharper cutting edge. Not necessarily a perfect edge, but sharper than what was there before the acid etch. A bath in the soda to neutralize the acid, and then a good rinse to remove the soda.
Now, you're talking! That file should probably be as clean as you can get it before trying to do something chemical with it. Hot water and a strong alkaline cleaner and a good scrub, why not? I think the top edge is etched more than the bottom, it almost certainly is in the electrochemical process. If someone out there can do some metallography, now's the time! All we ask is a nice "before" and "after" picture, maybe fifty power. I've already used video microscopes that came with software, you could make measurements.
I heard about sharpening files over 50 years ago but forgot what type of acid to use, thanks for the refresher. Too bad that I am now too old to need the information.
I found having my old rusty files hard grit blasted cleaned them perfect and restored cutting performance. Experimented with grits and found silicon carbide grit in medium(80) did best job.
If the gullets are deeply packed with rust then yes grit will remove that but it will also Nick any sharp edge tooth that you've already have. Especially large coarse Grit . Anyone trying ball shot or well used Steel split shot will just peen over the sharp edge. 80 grit will make a really jagged Cutting Edge serrated should try something a lot finer or even use baking soda as the blast medium which is softer than the steel and won't dull the sharp edge but will remove the rust and oil , crud , Etc. Mechanical engineer.
+Marcel Timmers I wish Dale had addressed this. Yes, the acid is actually removing metal from both sides of the file teeth, leaving a sharp edge. The total amount of metal removed must be equal to or greater than the surface area of the dulled edge. This technique works great a few times, but eventually the etching process becomes too uneven, and while still sharp, it can be hard to get a clean finish with the file.
+BikingMNViking It works for both, but as you'd expect, you'll see a quicker degradation of the finish from single cut files, which you are most often using for a finishing pass, anyway.
Thanks for finding the Popular Mechanics article. That answers the "I won't believe it without photomicrographs crowd." I wonder what their next objection will be?
Hey guys, if you don't like the idea of acid sharpening don't use it. It does not matter to me whether you need to find reasons to contradict the idea or not, but some of your comments are really a bit thoughtless. Technically you probably could use acid to sharpen knives etc, but you would not use it. The knife is a thin tool and eroding away some of its thickness is unhelpful. Chisels do not suffer from a lack of thickness, but eroding metal would alter its dimensions, also the erosive process is not very uniform, so getting a nice even sharpen will not happen. Drills also do not want to have their dimensions altered. Also with the drill bit the angle of the cutting area is quite large, unlike the angle of the cutting part of a file. The result would be minimal sharpening for significant loss of metal and loss of dimensional accuracy of the tool. Surely, the proof of the pudding is in the eating. Just try it.
The idea of sharpening drill bits as a test of the process has been brought up before. The differing actions of a file and a drill bit are the reason it isn't used to sharpen drill bits. Drills use the width of the point to define the diameter of the hole that is drilled. Acid removes metal from every surface it comes in contact with. The drill bit will become smaller in diameter just as fast as it becomes sharp. You end up with a drill bit that is sharper but with a random sized diameter The same, two surfaces being eaten away, process exists because the diameter is the measure of the distance between the two sides of the bit. It will work on a knife but who wants a thinner shorter knife? Besides each of the other suggested arguments against using acid, points out a device that is normally sharpened in a different way, as an example of the acid process being a failure. If it were as easy to run a stone down the edge of the files teeth as it is a knife we all wouldn't bother with the mess of acid sharpening. Milling cutters are ground on center grinders because they have fewer flutes than a file would have in the same distance. The operation of the file doesn't depend on it's width or thickness as long as it is sharp and strong enough to not break during use. 😊 If you would like a good history of files, how they are made, and used I recommend The File It’s History Making And Uses by Henry Disston & Son. Upload of a copy from the Stanford University Library is available here. play.google.com/books/reader?id=1mNBAQAAIAAJ&printsec=frontcover&output=reader&hl=en&pg=GBS.PA7
Nice Dale. I have seen this before, but with vinegar over night. PVC pipe makes a good container. also It should be noted that this is obviously a chemical sharpening and it will only work a few times before the acid simply just dissolves the cutting teeth.
My gramps taught me to do this years ago only using white vinegar. If you use household which is 5%, the files need to soak for up to a week, depending on how bad they are. Although this does take substantially longer, it is much safer and less expensive than using sulfuric acid. You can also use industrial vinegar or acetic acid but it is much more expensive and a lot stronger at 30% and requires the same saftey precautions as sulfuric acid. I have also used muriatic acid and it works just fine. Just keep the dilution to 10 to 1 or ten to 1.5 water/acid and keep an eye on progress so as not to let it go too far and ruin the files. Keeping files all piled together is a sure way to dull tgem quickly. Store them separately in a rack or make covers for them to protect the teeth
My last year and a half in the US Air Force I worked at the largest rocket sled track in the free world. This is at Holloman Air Force Base in New Mexico. The time I was there we tested components for the F-16, the Space Shuttle orbiter and the B one Bomber. The unit number for the squadron has changed in the last few years, but there are several videos on YOU TUBE under high speed rocket sled track. It was the most interesting job I ever had.
As a licensed tool and die maker I can tell you that you did not sharpen your file. You simply removed material that had loaded up in the gullets of the teeth. A "loaded file will not cut, so removing that material will make it cut better. To sharpen a file you must remove metal. Files are very hard but being the same hardness means that rubbing them against each other (as in a drawer) will actually dull the cutting edges. A good way to prevent loading when cutting soft metals is to first rub chalk onto the file. This will prevent the soft metal from sticking in the gullets of the files cutting teeth. The teeth on a worn file look shiny instead of dull. When THAT happens, throw it away. There is NO way to resharpen it.
It really dose sharpen the file. Give it a try, you have nothing to lose. I promise you, you will be surprised. One side note the file must be dull not damaged to work. :-)
If the teeth are rounded and the acid strips away an even amount over the entire surface area, it will make the teeth more narrow and remove the rounded tops, therefore making it sharper.
If this were true then you could take a razor sharp knife and put into acid and expect it to come out razor sharp but it would actually erode the thinest part first which of course is the sharp edge. Working as a toolmaker since the 1980s I have a strong background in metallurgy and how metal can be sharpened or lose its fine edge. As said earlier, the file may seem sharper but this only because acid has removed material from a clogged file not by making the edges of the teeth sharper. A clogged file will not allow teeth which are still sharp to cut.
Yup . Add some degreaser to the bath , and it'll take off all the baked on stuff that comes of buying used files . Found that 12v 6a will pit a file very quickly .
dear dale, I have a drawer full of dull files, think i'll try this. used the info on your lead-screw video to rebuild my logan lathe.cross slide. thanks for all your efforts to impart common-sense knowledge to the masses.ray
You are not sharpening the file, you are actually cleaning the grooves on the file, you may as well use a fine metal brush to accomplish the same results, just follow the groove direction to clean it.
Before denouncing this method of sharpening you should try it yourself. All of the people saying it wont work, have never tried it. All the ones saying it does work, have actually done it. You can prove it to yourself on paper if you dont actually have a file to sharpen. It is simple geometry that you can draw out on a piece of paper to understand. To see how taking a few thousandths of an inch off of the entire surface of the file will sharpen it, draw a cross sectional profile of the dulled teeth, including the rounded points. Then draw a continuous line parallel to the profile of all of the teeth, spaced inward by half, which effectively makes the teeth smaller. You will see that the radius of the rounded point becomes smaller- in fact it has likely become so small that it has come to a point. Try it.
Dont throw old files away.....you can sharpen the ends like a chisel to use on the lathe. The hardened steel keeps an edge longer. You can also make a great scraper by softening, bending the end over to a hook shape and sharpen to scrape. Also you can use the file made into a cutter to cut iron or aluminum on a metal lathe! The tang can be used for a small cutter. Use the grinding wheel stone to sharpen not another file.
using old files as turning tools is a dangerous idea, files are very brittle and put under sufficient stress could easily snap and cause an injury. Far better to buy good quality turning tools and sling the worn out files.
sorry don't get it. Spotless clean for sure but sharpened? Perhaps the small bent over edge of the dulled tooth will be eaten away by the acid leaving a sharper edge I suppose but will the cutting angle changed? Having said that, a dull file is worthless and this would extend its life I guess. Should treat files with the same care you do chisels
I missed the part about sharpening files but did catch your excellent instructions on how to clean files. Somehow I don't think the acid and soda trick would sharpen a kitchen knife. But a file might.
You can use the end grain of that 2x4 to clean the file, much like you used the flattened copper tube. I have been cleaning my files that way for forty years, works well.
Yup, my father taught me this trick in the early 70’s except he used full strength white vinegar. It took a few days but worked quite well. He also showed me how to forge a worn out file into flint steel to use for starting campfires. Miss him every day.
mine was the same....retired millwright...so many tricks...peace
if youre wasting hardened steel on a flint, youre a fucking moron. "forging"? son all you do is cut a piece off, you aint forging shit.
Sounds like an awesome guy!
So...how DO you forge a worn out file for flint?
Good memories thx for sharing
Thank you eho you have just saved me a lot of notes on buying more files.
Files are in use pretty much every week here for all kinds of tools and chains of saws.
These things don't last long now and of course they can cost one lots.
Re cleaning them will be helpful to me and my pocket in NZ.
I tried using sulfuric acid in my files and now I cannot recover all my data.
LOL
@@chrischiampo7647 Be like Hillary C.
@@papaike2 *killary
OhhNoo! All that Porn gone.. how will you survive?!
...Bruh
I was given a bunch of old files and decided that I had nothing to lose by soaking them in acid. In my case I used muriatic acid and let each file soak for about ten minutes. I then neutralized the files in the baking soda solution. Some clearly cut better after the etching and some didn't. It depends on what you start off with. And yes, the acid cleans the files beautifully. So for all you trolls who have made negative comments, you have several options: 1) discard all your dull files and buy new ones; 2) Have your dull files hydro-honed where you'll pay to ship them plus the cost of the process; and 3) Try the technique described in this video. It all depends on what your expectations are.
They can send me all the files they like.
You've confirmed what I thought, it depends on what you start off with. A real worn file won't improve from this methode, but a file that is just dirty and/or corroded might. Nice tip, think I do step 3 first to decide which files to discard (and to reforge into something else). Think I'll just use vinigar and let it soak longer though.
I was always taught that keeping files in a drawer where they could rub together was the worst possible thing you could do to it. I always keep my files separate.
There's a reason they're shipped wrapped in waxed paper... each file in its own pocket. Rubbing files on each other is how you get these nice bright curved lines on them.
you know he was making a joke, right. not trying to be rude or anything just really having trouble deciding if you could tell.
File steel is some of the hardest steel commonly available. By keeping files in contact with one another does not necessarily mean disastrous results ensue. File steel also has "toughness" which means that some abuse is normal. The way files are dulled is through pressure and extreme conditions such as exposure to water and other corrosive chemicals not through storage and random incidental contact with each other.
Yeah i was thinking, I've never heard this before. Like you i was taught the same thing. Don't rub them against each other and don't let them rub anything but what you are trying to file and only in the right direction.
@Steel and Tree Design the key to making a joke, is making it obvious. There is no indication of this being a joke. Most average people getting into working with their hands would take this video seriously and be mislead. Kind of a dick move kinda video if you ask me. Just makes this dude look like a fool.
I've just done this with all my files - everything from fine needle files right up to coarse rasps, and I'm blown away by how well it works. That's over 40 files I would otherwise have tossed - in NZ about $2k worth (as some were fairly specialized) One thing I would warn y'all of is being careful to neutralize afterwards, and then CLEAN the acidic patina out from between the teeth - otherwise they'll rust up real quick. As a jeweller I'm fortunate to own an ultrasonic bath, which was perfect for this job :)
And BTW yes - they were all clean beforehand - just blunt. In fact some came up sharper than new.
As a retired engineer with a small workshop my files are very important to me, rather than use a file card (which has steel pins) I use a brass bristled brush so it doesn't tend to blunt the file. When I was at school some fifty years ago, the metalwork teacher used this acid method to restore files. If you buy new files always keep one face unused for.use on brass, even files slightly worn files will not cut brass very well. I engrave the word 'Brass' on the uncut part of the file to remind me.
That's a good suggestion regarding the brass. A jeweler I know has separate files for gold, platinum, nickle and steel. Mixing flecks of metal between jobs would completely ruin the product.
I once made brass filings to mix with epoxy for a pottery repair. I spent hours filing a brass pipe fitting to make those filings. It never really occurred to me that brass would be harder to file but that project made that fact very real.
A file is much harder than a file card. You can not damage a file with it.
A file card will not blunten a file, the bristles do not engage with the file teeth, and are soft so even if they do (bent bristle etc) it don’t matter
I've heard that this was possible, but you gave us a great demo complete with safety warnings. It was a very good use of my time. I appreciate your good work.
Well said
something I do as a blacksmith is I take regular chalk and rub it on the file. it will lubricant and keep the file from filling up and clogging.
machinists also do this when using a smooth file to draw file a work piece to help reduce/eliminate clogging and pinning which can damage the surface finish.
Same thing... except I rub some borax into the file. whatever chalky stuff you've got, I suppose.
+Eagle Bird Knives Never thought of Borax or Soapstone, I have thoes by the pallet loads, thanks I'm going to try them.
Yes, 'load' the file with chalk to prevent it clogging/blocking in the 1st place, totally agree.
Absolutely. If you are filing aluminum and other soft metal that are sure to clog the file, loading it up first with chalk is your best bet. Been doing it for decades.
nice! and much faster than they way i sharpen my files (one tooth at a time). esp liked the copper pipe cleaner. i use wood, but I'll have to try copper on the stubborn ones. thanks!
+This Old Tony
Im glade you like it :-)
This Old Tony One tooth at a time? You must have been a dentist in a previous life!
I was taught to use brass to clean.
This Old Tony was
Copper pipe is a great idea
For those who prefer chemistry a bit less harsh you can use undiluted vinegar instead of 10% sulfuric acid- it just takes longer.
Incredible! Wonderful and useful! I was always taught at school to NOT put files together where they could dull each other - but to chalk them (although nobody ever showed me what kind of chalk to use or how to use it!!) and wrap them separately in paper or cardboard. We were told as an alternative to stand them in a block of wood with appropriate holes drilled in it, and placed where no metal would bang against them.
David Chadwick explained that he used French Chalk on files to stop them from loading up. In England, French chalk is another name for what I call soapstone here in the states.
It works great. The soap stone is slightly slippery and stays in the teeth of the file. Chips don't stick to it.
That is exactly what I was taught and still practice that to this day! I do have a handful of dull files and will try the method demonstrated in the video. Worst case, I'll make knives out of them.
@@OldSneelock thanks! that's a good tip.
@@OldSneelock watched an old instructional video on filing the other day and they were talking about French Chalk especially on the late stage of finishing the work piece.
this is the video: th-cam.com/video/P5Kp0WEGawY/w-d-xo.htmlsi=B77XjDmer3Es4XIw
Wow, this is great! I have a bunch of old machinists files that were my Dad’s, that are all dull but I didn’t have the heart to throw away. This will rescue them, thanks so much!
I've been hand filing saw teeth for 35 years or so and I've gone through many files. As such I've been using this method to save a few bucks. It really works.
0:56 Before I was allowed to be enrolled and studying at the High School in Aachen to become an Electrical Engineer, I had to absolve an internship, learning to weld, filing, sawing, etc.
The studies did not work out but what I learnt in the training workshop proved priceless throughout the next 55 years and still do.
I can even tell by the difference in sound pitches or notes the file produced before and after the process that you actually did a good job on that file, thanks for sharing this tip
Thanks for the comment. :-)
I have to say we all should be listening to the old timers more we would all have more knowledge . Those old guys and gals have made my jobs a little bit easier , thanks dude.
Exactly..the right way wasn't always the easy way..but in the end you have a quality product..with quality work
I use a very similar method on my files, but use a 100% salinity table salt brine and DC current to electo etch a few microns off the outer surface. Microscopic inspection before and after shows a clean sharp edge where they had been rough and rounding.
You would be better to use washing soda as the electrolyte as it is less corrosive and not hygroscopic if you fail to rinse some of it off.
It also does not release chlorine during the reaction.
Thanks! After watching the video and realizing what this process was accomplishing, I immediately wondered if using current to blast away the surface would also work!
Although I appreciate this is 2yrs layer, I have some questions, if you happen to get this notification...
- What did you use for the other terminal, and how far away?
- What power source did you use? (and at what voltage, if it is a variable source?)
@@DUKE_of_RAMBLE I used the file for the anode (-) and an old bolt for the cathode (+). I was just using an old 120 volt ac to low amperage 12v dc transformer like you would use to power a cordless phone base. An adjustable power supply would be nice but I did plenty of electro etching and black oxide coating with that basic setup. ( for oxide coating just reverse the polarity to deposit iron from the sacrificial anode onto the part you're coating.)
@@justindunlap1235 Awesome! Thanks.
So if you don't mind, last 3 questions (hopefully lol)
*Duration of time left in there to etch?* Based on whatever length file you were sharpening, and I can try to extrapolate from there to fit my file lengths.
*Was it a long cathode (bolt) or completely random, and approx what distance from the file?* In my (limited) experience, the length of each node, and even their angles relative to each other, drastically effects the path the current takes (electricity liking _"path of least resistance"_ and all that). So a short cathode, even if dangled mid-way, would end up doing more work nearest to it - potentially leaving the file with low spots where more metal was liberated from it.
*Size of container needed (or that you used)?*
Thanks again! 🤘✌️
I would use a plastic container approximately 14x18x4 inches with a very long bolt, long enough to touch the bottom and still protrude from the solution. I noticed I would get the most consistent results when the cathode and anode were placed vertically at opposite ends of the tank, as for duration it's not more than a few (3-5) minutes to get a decent etch on a 12 inch file ,depending on the power supply used, I've tried using a 12v battery charger before and was amazed at how fast it would etch, for oxide coating the longer you leave it the thicker the coating will be.
i was skeptical that it was going to do much, my files are pretty old and used hard, i wasnt amazed , i was absolutely blown away, they are like new ,it worked wicked awesome, mind bottling !
unclogging or sharpening this is something lots of people did not know how to do and will help them with there files working again and its very easy...nice job.
Dale,
Thanks for this helpful trick! This afternoon, I've been working on restoring about 8-10 files that I thought were total junk... just tried the first 3 that I took out of the acid bath, and they cut like a new file!
I used Muriatic Acid (hydrochloric acid) instead of sulfuric.
Probably the best tip in this video is to use a piece of copper pipe to make a file scraper... it works better than any file card ever created for cleaning the file... and is probably responsible for 75% of the success of this method.
Thanks again, I've now got about 10 more "new" files for the shop that were destined for the scrap bucket!
Thanks for your comment, I'm so happy you saved those files. :-)
Works like a champ!
Maybe people should try it before making comments. It's amazing how smart we think we are. Ignorance is a curse.
I like the vid. Great job.
Great video!
For those of you that have one, and are still into analog, this is also covered in The Machinist Handbook
Start at 1:40 if you wanna skip opening comments.
Thanks
wow I've been machining for 19 years and this is the first time I've heard of this. awesome
Thanks
I learned the same trick as an apprentice, the only difference was that it was a 9% sulphuric acid mix and it was left in the solution for 2 hours. Afterwards, you put the file in cold water and agitated for a bit. It worked well. I never did it a second time but I remember being told it only worked the once. Good post, thanks.
Hi The run Reaper, Thanks for your comment. I like stories like that.:-)
yes, I am a swordsmith, and I really go through files (filing spring-hard steel a lot). copper and wood both work. For small files, get a popsicle stick to clean them out. Same trick.
Am pattern welding files into knives with high nickel saw blades for contrast put into nitric to reveal. I imagine the nitric acid(dilute) would work nicely and quickly for file sharpening.
1: never heard of that one with the files self-sharpening in the drawer.
2: That drain cleaner is water, detergent and some acid... you need concentrated sulfuric acid to create that exothermic reaction and the concentrated sulfuric acid looks like yellowish/brown oil or thin honey.
3: removing rust and slightly etching the file to sharpen it with acid - pure genius! Onestly!
Thanks for sharing!
Thanks for your comment. I can't believe you have never done the file in the draw technique before. LOL
concentrated sulfuric acid is clear. no tint.
unless it is adulterated.
You have to read the labels. Some drain cleaner is pure concentrated sulfuric acid.
I always use citric acid, it works just as well but is less bad for the environment. Also, I use a 40volt dc power supply so as to speed up the process like in Electro polishing, the electricity makes more metal erode of the planes than of the points and the file becomes even sharper. After I use the citric acid I bring it to a recycling company, fresh citric acid you can pour down the drain, it will be deluded and become harmless. Citric acid that is used with metal can be full of chrome 6 and 7 so recycle it responsibly. The acid I use comes from citrisurf(brand name) ps. great video not many people know this trick and throw their files away
Thanks f0r your comment
This is electrochemical machining, and probably much superior. Does some iron plate out on the Cathode? Is the cathode lead or stainless or does it matter? I think this is the right path and hope you will publish something.
How do you connect the power supply? I tried something similar with a 12 volt battery charger and just fried it. Didn’t know who to ask but hopefully you can explain the correct method?
Electroetching will be faster *but* the tips of the file teeth have a higher electrical potential and will erode faster and as a result, the files won't be as sharp, it may even dull the file more, depending on the electrolyte, voltage and current. That what the process of electropolishing does, it removes the high points on a surface to produce the polish. There are shops that specialize in electro deburring.
Interesting! I may have to try that twist..
Hard to believe someone thinks file-to-file contact would *sharpen* rather than dull it.
Also, you have the sweetest vise I've ever seen.
An old machinist taught me many years ago about using a soft piece of metal to clean a file. I’ve still got a piece of brass shim shaped like an L that I use. I’ve used aluminum, it works fine. Had a piece of brass dar stock that I had used for a punch pin that had mushroomed the head, that mushroomed head worked well. Obviously, the copper you used here does the trick. I’ve never used chemicals to clean a file, but I’ve not ever had a rusty one. Well done and thanks for the video.
Ive been a tool maker for 30 years and clean my files with a wire brush. I buy new files sometimes, they are a pleasure to use.
I do the same but my brush is on a bench grinder..lol
This is a time honored method, and it does help to improve the files cutting ability. The acid etches the file steel. This method does have its limitations though. For example, files that have been abused, stored or used improperly. All of which are a very common issue.
I have seen many a file just tossed in a drawer or bin with other hardened steel tools and files. I have also seen files used with saw like, or in a scrubbing/sanding motion. This will rapidly round/roll the file teeth over. Even milder (softer) steels can have this effect on a file if it occurs often enough.
Or they attempt to file on steel that has been work hardened, think, an edged tool (such as an axe) that has been used to strike something hard such as stone. This high speed impact crushes the edge of the tool, which causes the molecules at the site of the impact to become heated and compressed.
After the impact the molecules at the site of the impact rapidly cool and often become harder than the file being used to resharpen the edged tool. This sharpening attempt literally rounds or rolls the fine edges of the file over, thus, destroying the cutting edge of the file. Files can only cut materials softer than the file itself. If the steel is too hard for the file, the steel must be carefully ground to remove the work hardened steel.
Any action that causes a file's steel to become hot will soften the steel of a file, making the file useless as a file.
To me all of these forms of file abuse are indications of clueless and unskilled workers (aka: greenhorns). Or... people that just don't give a damn.
Every winner was once a beginner…
You weren’t born with natural knowledge of metallurgical science and file maintenance. Greenhorns can learn
In an old book I have re sharpening files it says: Immerse file in acid for a short time. Then pass lightly a piece of cork along it to remove acid from the top of the teeth. Immerse again. Pass the cork and repeat as necessary. What is being done is actually to not let the acid eat away the top of the teeth but only the valleys. Never tried it meself.
this would work.... but u would need to go at it a while
That sounds like sound advice.
That is not very rational thinking. First the valleys are not dull the teeth are. Second the second you dip the file into the acid it is back working on the teeth.
@@thinkfirst6431 Actualy, it is very rational. You are just not getting it. Luckily science does not give a rip and it just keeps on doing what it does even though some of us are just a little to invested in cognitive dissonance to understand it. If you really refuse to accept proven concepts then just send all your dull tools over my way. I get a kick out of bringing old tools back to life. Save a grip of cheddar in the process.
@@edstimator1 Actually it is not very rational. no one ever cut anything with the valley of a file unless it was ground down into a knife. The acid is doing the work the cork might at best be wiping some of the sludge off of the top of the teeth speeding up the process an amount not worth the effort. The cork is too soft to effect the metal and would absorb some of the acid so that your just rubbing the metal with a soft material soaked in acid.
The acid is what is doing the work. The acid eats the metal at a constant rate over all of the file. The reason that it works is that the tops of the teeth are worn at different rates. The very thin tops are dissolved at a "faster" rate than the thicker worn parts of the file so that when the worn parts of the teeth approach a sharp edge again the thinner parts and the thicker parts join in a "sharper edge in roughly the same time making the surface of the tooth more or less "sharp". No one gives a crap how deep the valley is, only how sharp the cutting edge of the file is.
The acid dip only works as long as the hardness of the file is uniform in depth. If the hardness varies so will the chemical sharping. Acid dip works, the cork is just BS.
Theoretically speaking, using your files correctly should keep them sharp... this is a great instructional on how to clean them up, which is also necessary!
thank s
Thank you…looking forward to trying it. The most important takeaway was the gentleman sharing lots of knowledge with you!!
When you get new files, keep them separated and dry where they won't bump into anything. I have my own handmade rack I keep them in, much like a knife block. Card your files often and keep them chalked. Use the proper file for the job at hand. If you take good care of your files, you won't have to resort to dipping them in acid, which only works for a little while (the file will quickly dull again) with diminishing returns. For all this trouble, you might as well just purchase a sharp new file and take good care of it rather than handling caustic chemicals.
At last!! someone with some common sense.
We were taught to use blackboard chalk when filing , this stops the teeth from becoming clogged with metal filings . Regular brushing & reapplication of chalk to the teeth while in use & storing of files protected in cloth help make a file stay sharp for a very long time
Thanks for sharing. As Michel Nadon said earlier, it would be nice to have visual proof of the effect of acid etching on the cutting edges of the file. In theory, what you are promoting might work if the acid etches all surfaces equally and a round tip will become a sharp tip as a consequence. However, I think we need to see this happening to be convinced, My feeling is that sharp edges will be strongly attacked by the acid and come out rounded.
I follow your logic and agreed with it, but it dosed sharpen the files. I don't know why all I know is it works. :-)
Thank god for you tube and passing this old timers trick onto the next generation! Keep up the good work!
So fortunate to run into a person with knowledge and stories from the 50s. TU on vid.
A similar process I tried does sharpen dull files. Whether the system used here sharpens them depends, I suppose, on how badly dulled they are. The copper cleaning tool is a great tip. I used muriatic acid from a masonry supply house and vessels made of PVC sewer pipe with an end cap cemented in place. I left the files in for many hours which ate away a lot of steel, too much in some cases. Worse, the fumes seemed to alter the chemistry of my shop. Here in a dry part of the country I'd never had rusted tools. Since the acid etch everything wants to rust so do it outdoors.
This a common problem with hydrochloride (HCl or muriatic) acid - even the fumes from an imperfectly tightened lid on the HCl bottle can cause corrosion through your shop - best to store strong acids in their own steel (sacrificial) cabinet with a bunch of seashells in it.
@@mikelastname Sounds like wise advice. Thanks.
Great information and education, thank you. I now have 3 generations of files to clean up.
Is a generation still 20yrs ?
Good video, I've never heard of using acid. I keep my files clean and not banging around but this will keep them more usable longer, then I'll make knives or tool bits out of them, great steel.
I have a drawer full of old files that are VERY dull but being a pack rat I didn't have the heart to scrap them. ( always thinking I could do something with them)...
Now I have a mission. when I get a chance I will try your idea out.
thanks for your video and knowledge It's amazing that if you get a chance to spend some time with your elders what they can teach you. They didn't get old sitting under a tree.
I am a retired auto tech and I have 4 sons. when ever we are working something and we are stuck on how to fix the problem most of the time I will come up with a plan on how to get around the problem. Its to the point now that they teach me things. When I do and it works I just tell them that I "Read it in a book once" The book is----" life experience. "
their book is growing also.
try this, take one random file and leave it soaking in white vinegar for a couple days. compare it to the experiment above. i'm curious to the results. :)
ive used vinegar to achieve the exact same results as this vid so Id appreciate a 3rd party opinion.. thanks Greg
You could always make them into knives.
Lol, I buy a lot of garage sale files to make tooling and knives out of, but after cleaning they work too well as files. If I make a knife or something out of one of them - seems like I always find a use for the file I just destroyed.
That was awesome!!! I have so many of them that won’t work anymore and always wondered if we even possible to re sharpen files but you came to the rescue!!!! Thank you! ❤❤❤❤
Great tip! Old files can be recycled into scrapers, knives, lathe bits & makeshift vise jaws too! Thanks!
The steel in old files is also a favorite of custom knife makers
Nice comment :-)
Do NOT use them as lathe bits ---very dangerous
@@davidwrighton3914 You are right. Files are too hard and brittle for lathe bits. But they might work if you tempered them to make them just a little tougher and less brittle.
A soft aluminium strip, run across the full in the same direction as the cut in the surface will form teeth and clean the old filings out allowing it to cut again . A blunt file is usually just a clogged up file . If it's dull , you cannot sharpen it
A strip of brass, pushed across the file at the same angle of the teeth will work even better.
Doesn't the sulphuric acid dissolve the metal making it thinner at the teeth sharpening it in a way?
or a stiff brush, everyone has that laying in their shop anyway.
Yup - it's known as 'chemical sharpening'. Even etching of the tooth surfaces leaves them with a sharp edge. Cleaning the file first is essential, however, as gunk in the teeth will protect the faces, meaning you'd only etch the tips, rounding off and blunting the file.
It will make them slightly sharper for a short time, it can only be done a few times and it will never be close to factory new
People arguing whether or not this actually sharpens vs. cleaning, have forgotten all about how we used to "acid dip" our muscle car bodies to make them lighter. Acid evenly removes metal from all exposed surfaces. That includes points, ridges and valleys. Let's picture ridges and valleys of a file. If the file is dull, the ridge will be a mini plateau. If you acid etch, the sides of the ridges will eventually wear away until the plateau becomes a thin ridge again. Thus, making a new point or ridge. Likewise, the valleys get deeper.
If you leave it in solution too long, you'll end up with flat bar. And if the file isn't extremely clean and wire brushed, all the etching action is happening on the left over crud, and not much on the actual file.
Thanks for your comment. :-)
This is how I've sharpened files for 45 years but I didn't know about the copper pipe. Thanks!
Glad I could help
I have successfully done this but not in such a clean and safe manner as you demonstrated. Thanks for showing me the right way.
LOL
Old files can make great knives that how I sharpen mine.
@@jerryking1434 fukkin idiot ... You turn it into a knife. It's called recycling.
You cannot sharpen any file... unless you have equipment to cut such fine, angled, and uniform angles...
Or have you mastered Nicholson ??
Kenneth Kustren your either super slow on the uptake and can't process humor, or you're just a super big asshole that wants to spread his asshole comments around and put people down. William Miller was making a fucking joke, and yeah wasn't the funniest but it made me laugh. You need to get some help with that because it's going to end up destroying you one way or another.
William Miller I've made several knives from old files myself. Just remember to do both heat treatments so they aren't so brittle then to put temper back into the file.
But how do you use the knife as a file after you turn a file into a knife.
@@kennethkustren9381 your mother
Can you show us a close up of the teeth before and after the cleaning? I'm intrigued what this actually does to the file.
It dissolves the surface which brings the teeth back to a sharper point, if you try it yourself you’ll see what I mean, if the teeth were rounded before, the two intersecting planes of the tooth dissolve evenly bringing the two planes closer together and therefore deleting the rounded tips of the teeth, I agree, if he has the close-up cameras ability to show it, it would be helpful to explain using the visual aid to show this effect. Even a drawing would be helpful
@@b2manufacturing Thanks for the explanation. It seemed sort of improbable but now you explain it the process makes sense.
I think it’s actually cleaning the file I think the acid loosens debris from the tooth relief .
@@b2manufacturing the rounded cutting edge will as fast resolve as the surfaces. I don't think it will make it sharper, but the proces will clean it more up, so the teeth will become more corse regarding the high and lows of the teeth, so it feels like it's sharper again.
Better buy a new file, they are not that expensive.
Thank you! By the way, in Britain we are always told to use a file handle on a file to avoid cuts in the hand and wrist! Best wishes, Luke Wiseman
Thanks for sharing the old timers instructions with us. I just love this sort of thing, because if you didn’t know anyone who knew how to do this…then you didn’t either.
Best file sharpening video I found so far and I've watched a lot of them
I have been doing this for many, many years, but I now use a piece of 2" pvc drainage pipe, capped at one end, so I can fill it to cover the whole of the cutting parts of the files!
Great Idea, I'm going to have to start doing that.
@@BuildSomthingCool Can you also teach me how to sharpen each file tooth too please. My 5th and 7th tooth are blunt and it's making a funny sound, kinda like it's out of tune.
I always use vinegar and let them soak for a day or too it works really good and is much safer than strong acid ..
Citric acid works quicker than vinegar. Or add salt to your vinegar. You should be down to an overnight soak. Both superior safe solutions though.
The copper tube part is one of the most important steps in cleaning a file and you didn’t even barely mention it. When you run the copper flattened tube over your file, the softness of the copper allows it to form down into the teeth of your file and clean it. This is one of the most important steps. You need to elaborate on that and how it works if you ever make another one of these.
I heard about this trick many years ago from an old time sharpener. He also used files for a living to sharpen very fine cutlery. He said they would be ok but not great. I guess i will have to try it for myself.
Retired machinist here. This actually does work on your files and it will also work on endmills made of High Speed Steel.
the solubility of sodium bicarbonate is around 100 g/L at room temp. So if you have a water volume of ~4 L, like it looks like you do, you would need right around a pound of baking soda before it reaches its saturation point (Ksp). Just letting you know.
Btw, ego in their right mind would think that storing files I drawer, and letting them rub together, would sharpen them? That makes no sense whatsoever. It would do the opposite.
It does make them duller. Been around them for 40 years, using them for 30.
thanks
Andrew Delashaw pretty sure it was sarcasm.
Bah! If you'd rinse the stinking files off first, you'd only need a little bit, it doesn't have to be saturated! Just throw some in there.
Do this outside. The fumes from the acid are HIGHLY CORROSIVE do not do this process inside. The fumes from the acid will settle on anything metal and corrode the surface and you will have rusty tools or machinery. I do decorative acid etching and found this out the hard way when i did some etching under a cabinet that held all of my taps and drill bits. It corrodes the protective coating and made everything rust.
In a similar way I found that bleach vapors will rust any steel that they touch. My binoculars were stored in a cabinet. The laundry soap was moved to a lower shelf in that same cabinet so it would be easier to reach. When I found my binoculars that fall it took quite a bit to clean off the surface rust. Good thing my guns weren't in the same cabinet.
Do this outside! Or in your toilet!.......... >.>
You must be a bachelor. 😈😈😈😈
.... It's drain cleaner for crying out loud. Nice haircut though.
Big Dan No slam intended Big Dan. I just know if I ever used the toilet for sharpening files I would have to have a food taster for the rest of my life.
Despite that it has it's merits. Fresh water anytime you need it. Self rinsing. Porcelain bowl that isn't bothered by acid. If it wasn't for winter hitting Michigan 6 months out of the year I'd be seriously thinking of installing one in the shop for just such uses. :-)
A clear explanation of this process and several similar metods can be found at page 235 of Workshop Receipts: For Manufacturers and Scientific Amateurs, Volume 2. It's available free from Google books.
thanks for sharing this information. :-)
Happy to. When I first learned about the process from Jim Thompson on the Old Tools Mailing List I was a bit skeptical. It sounded too good to be true. Jim had never steered me wrong so I tried it. It worked. I had some growing pains learning how long to leave the files in the bath. A couple of Swiss cheese files convinced me that forgetting them was a sure route to failure. :-)
When I knew it worked and had finalized the process I decided to share it. I expected a hundred or so people that I regularly corresponded with on the list would be interested. Little did I know it would be one of the most viewed videos on my channel.
Then along comes Colin Riley on your channel. Next thing I know your video is at a quarter million views and climbing. My video is at sixty thousand and climbing, and my channel has passed three quarters of a million views overall.
Colin may be a pain but I really appreciate him starting the whole "It's only cleaning" meme.
I remember this method being used by file cleaners on the streets in Old Delhi India. Thank you Dale..
Pretty amazing... NOTE: Old golf balls make great file handles... at the very least protect your hand from the file tang.
Hi Timothy, I really like the golf ball handle think. :-)
i was taught that if a flie dose not cut clean it with a file card .
but how dose acid which eats /erodes material actually sharpen .
as a file is hardened you would need a diamond sharpener
more important never use a file with out a handle. you are showing your true professionalism
please correct me if im wrong so i can throw all my qualifications in the bin
If you're the type that always grabs the file brush when they grab a file, you may never need to do anything further. This is for when the rust and gunk build up so much that the file card won't cut it, (while a file brush removes chips well, it doesn't do such a great job of polishing the grooves). As soon as you remove the oxidation from steel, it comes back. If the rust gets to the point the brush can only remove the rust from the very edge you'll find yourself using the brush more often. Just the act of using the file helps to clean the edge. Like I said, using the brush often means you might never have a problem. Rusty garage sale files? They need more than a brushing. The deep groove in a file is just as important as the cutting edge - the chips need a place to go or they act like bearings - not good if they are full of rust.
During use the tips of the file teeth wear away. That is normal wear. As the file wears it begins to skid over the metal rather than biting in. At that point it is a viable candidate for either hydro-honing or acid etch sharpening.
If the file is abused, banged around in a box full of tools, run against hardened steel, or dropped so that the teeth are broken and chipped they are not candidates for hydro-honing but only because of cost. They can still be acid etched. Without shipping costs and the time involved, if you are able to save only one in three it's a good deal. Perhaps most of the file is okay with just one side screwed up, or one end. With no appreciable cost involved, what do you have to lose?
If the file is a little rusty or dirty, use a file card or perhaps a soft steel bar, like I use in my file cleaning video, to scrape the rust and dirt out of the teeth.
Something I haven't noticed in these discussions is any comments on pinning. It's not the topic of the video but if we talk about cleaning, as nearly every post has mentioned, then describing the things that create the need for cleaning should be defined. Pinning is when the gullet between the teeth becomes filled and stops the tooth's cutting edge from contacting the surface.
If you are having this problem then cleaning will be an endless effort. It is caused by the teeth being too fine for the chip load. Go to a larger file with bigger teeth.
Duncan Harris: I think one reason to throw your qualifications in the bin is that they should have taught you to look into statements/ processes offered on this video before posting negative statements of your own, just try it, then you can post a valid comment! (I would have thought that anyone with any kind of qualification would not be an armchair critic).
tell me where the shapening comes in ? as pointed there is an etching effect am i not the only one question. but as a professional my kit is looked after ( may be a snob having separate compartment for tools so they don't get damaged ) when you have worked in motorsports doing silly hours come back an then call me an arm chair critic
Duncan Harris As soon as you clean steel it starts to oxidize. An oxidized edge isn't as sharp as a clean edge. Whether we sharpen the edge by rubbing, scraping, grinding, or chemically treating the oxidation away - if the edge is sharper as a result we have sharpened it. Clean tools are always sharper than rusty tools, even if the difference is negligible.
It doesn't matter how organized and clean you keep your tools, when it comes to cutting edges made of steel, they will cease to work at an optimum level the longer they are exposed to oxygen. Leave a file in the tool box for 5 years, and even if it was spotless when you put it away, it's going to take some work to clean up. Will it need an acid bath? Maybe not - but if somehow sat in water a couple of those winters it will - and a file brush won't be the tool to use. Don't worry about it too much. I'm sure somebody out there has a tank hooked up to their toolbox to keep it flooded with nitrogen, I don't.
You forgot to mention that before the acid wash you must clean and completely degrease the file before dipping it in acid!
Acid will not touch metal that is oily or greasy.
good point
Actually acid dissolves oil and grease too
Mostly it does not, oil needs to be removed with a caustic solution or soap, acid will mix with water but as it is mixed with water it will not mix with oil.
@@Mentorcase For the price of cleaning a file before etching it, I'll clean it first with TSP. Thanks
my father taught me to use muriatic acid for sharpening files. baking soda is a great neutralizer.
thanks of ryour comment
I use that in my garage to get rid of mill scale. I came out the next day to everything rusted. If only I did research first!
I bought a Nicholson file a few months ago, that thing was used SO often, it’s getting dull, I think I’ll try this. Thanks!
I did it and works really fine! Thank you very much! You save my old files.
The 1k thumbs down is rather humurous, because they have no clue, my grandfather, a master craftsman & machinist showed me this almost 40 years ago, great to see basically the same process shown, I was throwing some what I thought was junk files away, he asked what I was doing, and showed me essentially the same thing, the only difference is he used diluted muriatic acid, & put them in 3" pvc with one end glued & capped, the other end just a slip on cap with a small vent hole, left them overnight, cutting edge up neutralized them with baking soda & they were razor sharp 👍
I know right? I have over the years sharpened many a file exactly like this.. Got the tip from a 1890's machinist book.
But....but...but...the master craftsmen of earlier time didn't have Google to prove???? That's right they became master craftsmen through years of work, experience, and training. This a simple process that has worked for many many decades before I was taught this method back in the early 70's. Believe it or not all you Nay Sayers it still works. It's really a simple process....quit over-analyzing it. If you want to pick the fly shit out of the pepper at least know what the fly shit looks like.
@@troyquintana1383 lolz, Great reply for all the little nay-sayers..
Looks like it works OK. I would be interested to see what a high powered microscope on the tooth profile on the file looked like before and after. If it just cleans the file, it would be useful enough but if the effect of the acidic bath alters the tooth profile it may be even better.
I just put that question in. I'd like to see that too. Maybe someone has done that already on YT. We should look for it.
I belive is called chemicaly sharpening, is a method used to sharp fising needles, razor blades, because it takes less time and is cheaper than going through multimple grits of sanding materials. They just sharp them up to a point, then dip them in accid, this will disolve the steel and leave the edges as sharp as steel can be. I wouldn't say is better because it also weakens the teeths of a file, and if you do this multimple times, i would say more than two times, it will affect the flatness of the file and it will eat the teeths. Is good method, i never tried it, but i played with accid to remoe some rust. For old files, is better to give this treatment then throw it away. And old files can be turned into other kind of tools, such as chisel, or marking knives.
excellent lesson thanks..
Thanks
B
A good source for tall, skinny containers for this use, chemical derusting, etc. are flower vases. Keep an eye out at yard sales, they can be had for pennies.
Do you think I could substitute muriatic acid instead? I know for sure it will still eat the steel which I feel like is what sharpens them.
Great video Dale! Could you show close up shots of the metal piece being filed before and after? It would be great to see the difference.
Great comment. next time :-)
Yeah what a shady ending geez!
Can I use this to clean my criminal file?
Bleach will work much better than acid. BleachBit in fact. The top criminals in this country used it successfully.
Da L. that's what Hillary uses?
Antifoul Awl
H
Antifoul Awl ACriminal file is nothing else than history.
Hi Dale, nice tip, but using the file without a handle... you were specific about safety with acid & wearing protective gear but not mentioning file handle ... tut, tut,
Dale, can I use muratic acid instead of the drain cleaner (sulfuric acid)?? Thanks in advance for any replies.
You can buy the regular drain opener at any Home Depot right
I have done this using plain cheap white vinegar. Leave the file in the vinegar 10 or 12 hours then rinse well and oil it or use some WD40. I know all of the anti- WD40 stuff but it works for me so save your keyboaed
my keyboard is already blunt... WD40!! pff!
Thanks for your commnet
To all you doubters (which I also was) ... this actually works - I've even checked under the microscope..
thanks for your comment :-)
Sure. It works great at cleaning out the teeth. Not sharpening though.
No shit cleaning a rough surface so clogged full of shit it feels smooth makes a surface rough again.
But that’s not sharpening its cleaning
who said rubbing file against file at the incorrect angle will sharpen them? iv never heard that
Miles11we
I think he was joking
Laurence Rilling I doubt it, I have heard a couple people saying it will work, similar to how you can "sharpen" knives by running their edges against each other.
@@danielnapast4955 he was definitely joking, problem is that this joke has weaseled its way into the shops of some people who are unaware and have gone on to repeat it. Whether they said it as a joke or not it was passed along so often that at some point certain people began to believe it.
It is always said sarcastically by some old salt claiming that he sharpens his files by throwing them in the drawer with the others and they sharpen each other, meaning, ...he doesn't sharpen his files. I would bet that some new blood heard it and could not identify the tone. Same guy that spends 6 hours of his shift looking for the blinker fluid and can't figure out why everyone is giggling under their breathe.
Its sarcasm....sheldon.
the file is mechanically cleaned to get the swarf out of the teeth, and a step not included is a detergent bath and scrub, to clean off any oils that may be on the file. Acid etches or dissolves the surface of the metal of the file...remember that each "tooth" has an upper and a lower surface and these are etched or dissolved. What is left behind is a somewhat sharper cutting edge. Not necessarily a perfect edge, but sharper than what was there before the acid etch. A bath in the soda to neutralize the acid, and then a good rinse to remove the soda.
Nice comments
Now, you're talking! That file should probably be as clean as you can get it before trying to do something chemical with it. Hot water and a strong alkaline cleaner and a good scrub, why not? I think the top edge is etched more than the bottom, it almost certainly is in the electrochemical process. If someone out there can do some metallography, now's the time! All we ask is a nice "before" and "after" picture, maybe fifty power. I've already used video microscopes that came with software, you could make measurements.
I heard about sharpening files over 50 years ago but forgot what type of acid to use, thanks for the refresher. Too bad that I am now too old to need the information.
I found having my old rusty files hard grit blasted cleaned them perfect and restored cutting performance. Experimented with grits and found silicon carbide grit in medium(80) did best job.
If the gullets are deeply packed with rust then yes grit will remove that but it will also Nick any sharp edge tooth that you've already have. Especially large coarse Grit . Anyone trying ball shot or well used Steel split shot will just peen over the sharp edge. 80 grit will make a really jagged Cutting Edge serrated should try something a lot finer or even use baking soda as the blast medium which is softer than the steel and won't dull the sharp edge but will remove the rust and oil , crud , Etc.
Mechanical engineer.
Hi mate. So, has it only cleaned the file, or has it also chemically sharpened that file?
+Marcel Timmers
It chemically sharpens the file
+Marcel Timmers I wish Dale had addressed this. Yes, the acid is actually removing metal from both sides of the file teeth, leaving a sharp edge. The total amount of metal removed must be equal to or greater than the surface area of the dulled edge. This technique works great a few times, but eventually the etching process becomes too uneven, and while still sharp, it can be hard to get a clean finish with the file.
Thanks for that mate. I was not sure of what had actually happened. Again thanks for the extra info.
+FXM For Single or double cut?
+BikingMNViking It works for both, but as you'd expect, you'll see a quicker degradation of the finish from single cut files, which you are most often using for a finishing pass, anyway.
Thanks for finding the Popular Mechanics article. That answers the "I won't believe it without photomicrographs crowd." I wonder what their next objection will be?
LOL
funny thats the only article that says this is sharpening that ive seen
Thanks for your comment. I wouldn't have looked in the description otherwise. Why doesn't this work for knives, chisels, or drills though?
Hey guys, if you don't like the idea of acid sharpening don't use it.
It does not matter to me whether you need to find reasons to contradict the idea or not, but some of your comments are really a bit thoughtless.
Technically you probably could use acid to sharpen knives etc, but you would not use it. The knife is a thin tool and eroding away some of its thickness is unhelpful. Chisels do not suffer from a lack of thickness, but eroding metal would alter its dimensions, also the erosive process is not very uniform, so getting a nice even sharpen will not happen. Drills also do not want to have their dimensions altered. Also with the drill bit the angle of the cutting area is quite large, unlike the angle of the cutting part of a file. The result would be minimal sharpening for significant loss of metal and loss of dimensional accuracy of the tool.
Surely, the proof of the pudding is in the eating. Just try it.
The idea of sharpening drill bits as a test of the process has been brought up before. The differing actions of a file and a drill bit are the reason it isn't used to sharpen drill bits.
Drills use the width of the point to define the diameter of the hole that is drilled.
Acid removes metal from every surface it comes in contact with. The drill bit will become smaller in diameter just as fast as it becomes sharp. You end up with a drill bit that is sharper but with a random sized diameter
The same, two surfaces being eaten away, process exists because the diameter is the measure of the distance between the two sides of the bit.
It will work on a knife but who wants a thinner shorter knife?
Besides each of the other suggested arguments against using acid, points out a device that is normally sharpened in a different way, as an example of the acid process being a failure. If it were as easy to run a stone down the edge of the files teeth as it is a knife we all wouldn't bother with the mess of acid sharpening.
Milling cutters are ground on center grinders because they have fewer flutes than a file would have in the same distance.
The operation of the file doesn't depend on it's width or thickness as long as it is sharp and strong enough to not break during use. 😊
If you would like a good history of files, how they are made, and used I recommend The File It’s History Making And Uses by Henry Disston & Son. Upload of a copy from the Stanford University Library is available here.
play.google.com/books/reader?id=1mNBAQAAIAAJ&printsec=frontcover&output=reader&hl=en&pg=GBS.PA7
Nice Dale. I have seen this before, but with vinegar over night. PVC pipe makes a good container. also It should be noted that this is obviously a chemical sharpening and it will only work a few times before the acid simply just dissolves the cutting teeth.
+holry7778
Good point
My gramps taught me to do this years ago only using white vinegar. If you use household which is 5%, the files need to soak for up to a week, depending on how bad they are. Although this does take substantially longer, it is much safer and less expensive than using sulfuric acid. You can also use industrial vinegar or acetic acid but it is much more expensive and a lot stronger at 30% and requires the same saftey precautions as sulfuric acid. I have also used muriatic acid and it works just fine. Just keep the dilution to 10 to 1 or ten to 1.5 water/acid and keep an eye on progress so as not to let it go too far and ruin the files. Keeping files all piled together is a sure way to dull tgem quickly. Store them separately in a rack or make covers for them to protect the teeth
My last year and a half in the US Air Force I worked at the largest rocket sled track in the free world. This is at Holloman Air Force Base in New Mexico. The time I was there we tested components for the F-16, the Space Shuttle orbiter and the B one Bomber. The unit number for the squadron has changed in the last few years, but there are several videos on YOU TUBE under high speed rocket sled track. It was the most interesting job I ever had.
thanks for you sharing your story
As a licensed tool and die maker I can tell you that you did not sharpen your file. You simply removed material that had loaded up in the gullets of the teeth. A "loaded file will not cut, so removing that material will make it cut better. To sharpen a file you must remove metal. Files are very hard but being the same hardness means that rubbing them against each other (as in a drawer) will actually dull the cutting edges. A good way to prevent loading when cutting soft metals is to first rub chalk onto the file. This will prevent the soft metal from sticking in the gullets of the files cutting teeth. The teeth on a worn file look shiny instead of dull. When THAT happens, throw it away. There is NO way to resharpen it.
It really dose sharpen the file. Give it a try, you have nothing to lose. I promise you, you will be surprised.
One side note the file must be dull not damaged to work. :-)
If the teeth are rounded and the acid strips away an even amount over the entire surface area, it will make the teeth more narrow and remove the rounded tops, therefore making it sharper.
I was wondering about that as well, if it removed the material evenly, if that wouldn't keep the edge intact.
If this were true then you could take a razor sharp knife and put into acid and expect it to come out razor sharp but it would actually erode the thinest part first which of course is the sharp edge. Working as a toolmaker since the 1980s I have a strong background in metallurgy and how metal can be sharpened or lose its fine edge. As said earlier, the file may seem sharper but this only because acid has removed material from a clogged file not by making the edges of the teeth sharper. A clogged file will not allow teeth which are still sharp to cut.
its going to remove the sharp tops faster than it removes the rounded tops.
I use electrolysis to sharpen files. Works well !
I have too. I like it as a cleaning steps before the acid bath.
***** I also did with the acid but hot phosphoric acid, really effective. Keep up the good work, your videos are very interesting.
Electrolysis uses much less materials. Only table spoon of baking soda is all you need.
How is it done?
Yup . Add some degreaser to the bath , and it'll take off all the baked on stuff that comes of buying used files . Found that 12v 6a will pit a file very quickly .
dear dale, I have a drawer full of dull files, think i'll try this. used the info on your lead-screw video to rebuild my logan lathe.cross slide. thanks for all your efforts to impart common-sense knowledge to the masses.ray
+Ray Pearce
Im glade you like the content in my video.:-)
This is a great way of fixing them ! My guess it eats away at the dull edge making it a point again ! Cool !
You are not sharpening the file, you are actually cleaning the grooves on the file, you may as well use a fine metal brush to accomplish the same results, just follow the groove direction to clean it.
Before denouncing this method of sharpening you should try it yourself. All of the people saying it wont work, have never tried it. All the ones saying it does work, have actually done it.
You can prove it to yourself on paper if you dont actually have a file to sharpen.
It is simple geometry that you can draw out on a piece of paper to understand. To see how taking a few thousandths of an inch off of the entire surface of the file will sharpen it, draw a cross sectional profile of the dulled teeth, including the rounded points. Then draw a continuous line parallel to the profile of all of the teeth, spaced inward by half, which effectively makes the teeth smaller. You will see that the radius of the rounded point becomes smaller- in fact it has likely become so small that it has come to a point. Try it.
Dont throw old files away.....you can sharpen the ends like a chisel to use on the lathe. The hardened steel keeps an edge longer. You can also make a great scraper by softening, bending the end over to a hook shape and sharpen to scrape. Also you can use the file made into a cutter to cut iron or aluminum on a metal lathe! The tang can be used for a small cutter. Use the grinding wheel stone to sharpen not another file.
Thanks for the comment
using old files as turning tools is a dangerous idea, files are very brittle and put under sufficient stress could easily snap and cause an injury. Far better to buy good quality turning tools and sling the worn out files.
sorry don't get it. Spotless clean for sure but sharpened? Perhaps the small bent over edge of the dulled tooth will be eaten away by the acid leaving a sharper edge I suppose but will the cutting angle changed? Having said that, a dull file is worthless and this would extend its life I guess. Should treat files with the same care you do chisels
interesting point :-)
I missed the part about sharpening files but did catch your excellent instructions on how to clean files.
Somehow I don't think the acid and soda trick would sharpen a kitchen knife. But a file might.
You can use the end grain of that 2x4 to clean the file, much like you used the flattened copper tube. I have been cleaning my files that way for forty years, works well.
thanks for the tip