The truth and the myth of hollow-grind sharpening
ฝัง
- เผยแพร่เมื่อ 4 ต.ค. 2024
- Will a hollow grind make an edge more fragile? Hardly! And I can prove it.
I highly recommend WoodturnersWonders CBN grinder wheels. They totally changed how I grind tools!► woodturnerswon...
(When you use this link to visit our sponsor, you support us!)
Subscribe (free) to Stumpy Nubs Woodworking Journal e-Magazine► www.stumpynubs....
Follow us on social media►
Instagram: / stumpynubs
Twitter: / stumpynubs
Facebook: / stumpy-nubs-woodworkin... - แนวปฏิบัติและการใช้ชีวิต
![How a PRO uses the WorkSharp Ken Onion Elite MK2 [Dexter Ewing]](http://i.ytimg.com/vi/8z0eN3UypYI/mqdefault.jpg)
![How a PRO uses the WorkSharp Ken Onion Elite MK2 [Dexter Ewing]](/img/tr.png)
I highly recommend WoodturnersWonders CBN grinder wheels. They totally changed how I grind tools!► woodturnerswonders.com/
(When you use this link to visit our sponsor, you support us!)
Subscribe (free) to Stumpy Nubs Woodworking Journal e-Magazine► www.stumpynubs.com/
the reason I asked so many questions is I have just purchased 2 CBN wheels, 180 &350, along with a low speed ricon. I have the trend 1000 with their cutting fluid. I guess the Shapton's are next. Thank you for all the valuable info you have shared over the years.
@@pepper7144 The 180 and 350 are great for shaping new bevels and repairing edges. Your day to day sharpening will be done on the 1000 grit stone. Many times, you can just follow that up with a leather strop. That's sharp enough for most chisel work. But when you need something REALLY sharp, such as a smoothing plane, or to pare soft end grain with a chisel- that level of sharpness would take a lot of stropping by hand (because of the wide difference between the 1000 grit diamond and the leather strop). That's why I have the 5000 and 16000 Shaptons. They do what the strop does, only faster. (Frankly, I most of the time strop on my Tormek, which is by far the fastest way to a razor sharp edge. But that's a whole different system.)
"Tiny things become big problems if we make them out to be so", those words of wisdom apply to so much of life.
Yes they do.
I always learn something new with Professor Hamilton.
This is the best visualization of the issue I've seen.
its nice to see someone NOT go off on a tangent when talking about hollow grinds.
pun intended
Edgy humor, always cuts me up.
I liked his use of circular reasoning.
@@micahrufsvold Well, to a degree.
James, I don't know if I've ever seen any of your actual craft work; however it is natural to assume, from your expansive and encyclopedic knowledge of woodworking, that you make extraordinarily clean and beautifully crafted pieces. One thing that is certain, beyond conjecture, is that you are a Master teacher. I've been a professional acoustic guitar luthier for 21 years, and I know a LOT about that work. But every video of yours I watch, I learn something new and useful. I'm so grateful to you for that. Even though lutherie is a lot different from cabinetry and furniture making, so many of the same concepts apply. The way you explain and demonstrate everything with such straight-up, no BS clarity and practical craft wisdom is just priceless, and is a rare talent. Deepest gratitude to you for sharing this universe of know-how and knowledge that you possess!
No nonsense and no BS. That's what I appreciated about your videos. When seasoned with a bit of your wit/humor, that's the icing on the cake. Thank you once again for bringing much needed light to a confusing issue.
Excellent explanation I’m 71 years old and I’ve been hollow grinding senes I was 24
Great info, James. Thanks. People will argue about anything without knowing the facts. Stay safe.
Bill
Thank you for a breath of sanity to counter all the rabid arguments. Me, I consider myself still a newbie - I'll take any angle (within reason) that makes the cut.
I love the way James SEARCHES for truth in his craft. His dogged approach usually bring clear, concise answers. Bravo once again!
Thanks for sharing with us James. 🙏🏻🙏🏻👍👍👏🏻👏🏻👋👋
An excellent and very clear presentation Mr. Nubs. I hollow grind, but unless I'm re-shaping the tool I usually grind just close to the edge leaving a small flat. This is to reduce the risk of burning the steel, and to not grind away more than needed (extending tool life). No doubt many others do this too.
Another ball kicked solidly through the post nice one Mr H
I love how you take a scientific approach to debunk myths. Nice ending!!
This is an interesting subject I'd never thought about before. Great insight, thank you
Often when I watch these videos, I ind myself repeating my favourite line from iRobot: "Of COURSE Viki! Your logic is undeniable!"
These as professionals sharpener is why I didn’t like the concave grind. But you have opened my eyes.
after reading the book " the razor edge book of sharping" none of this has bothered me.
great video sir.
Really good mate , too many will argue the "ins and outs of a ducks ass" as we say in the UK.....bottom line , it makes no applicable difference that is noticeable in practice....Well said and well explained :)
"ins and outs of a ducks ass" water tight either way!
Nobody in the UK is calling it a ducks ass, it’s an Arse
@@johnrichy2k6 I wish that were true, but more and more English now speak American, making route rhyme with out rather than boot, for instance.
I really enjoy your videos stumpy. There are a lot of youtubers whom state and claim oodles of hogwash and misinformation. You are not one of them. I know that I’m getting good and accurate info from you. Keep it up!
Perhaps the best (and most well-reasoned) discussion of this topic I've seen. For my tools I use an approach similar to yours and my edges are obscenely sharp and stay that way over a decent amount of use. People get way too wrapped in in the minusciae when my bottom line is always: Did it work? Safely? Comfortably? If all three, done with discussion.
Excellent explanation.
Love your stuff, man.
Your videos are very informative and you always give "real world" examples of how things work. Thanks for showing us again that sometimes we can overthink things that aren't even important or relevant to how our projects will turn out.
My hockey skates have a 1/2” hollow! Never had a problem! Lol
Totally agree, dude. It's definitely not a big deal. 😊
Thanks for the video!
Stay safe there with your family! 🖖😊
Hey! Stumpy vid on work sharp convinced me I needed it. Now I think I need one of these wheels! I should probably just actually use chissels and see if I'm good with what I have.
Thanks for bringing a touch of common sense to woodworking.
Thank you, Sir.
I'll keep this in mind when I am calibrating how many microns to allow for the wire-edge that has to be removed by stropping, so that I may select the appropriate polishing compound and leather species, grain, and tanning technique. Of course, this must be adjusted for seasonal temperature and relative humidity to ensure that any oxidation impurities that may form have a suitable crystalline structure so as to compliment the cutting process. But everyone already knows that.
Not sure if your sarcasm is directed at me, but I think this video has the opposite affect- it simplifies things.
@@StumpyNubs Exactly, and that clearly violates the code of the omniscient woodworker. Obscure and completely irrelevant complexity is an essential element of the hobby, and therefore your contribution must be counteracted immediately, or novice woodworkers everywhere will start to believe that sharpening is not a dark, mysterious process only able to be performed by those that have worn plaid shirts and beards for over 20 years.
“He blinded me with Science” … great video Stumpy!
It is insignificant as you say. I agree. It (the hollow) is there and some on the Tormek forum argued with me that the metal behind the edge was not reduced. Reduced solely by the use of the wheel that is.
James -- This is another excellent video. You clearly demonstrated that the difference between a hollow-ground edge and a flat bevel is microscopic. Most of your illustrations used a 6" grinder. Many of us use 8" or larger wheels. With such wheels, the difference between hollow-ground edges and those with flat bevels is even smaller. I have a CBN wheel mounted on my Tormek. I KNOW there is a hollow-ground bevel, but I cannot see it with a naked eye. For my money, this is -- and always has been -- a non-issue.
Thanks, this video also made it clear 6” wheels are perfectly fine. I was caught up trying to go for the 8” on my 6” grinder. But the difference is negligible
This makes perfect sense good especially the conclusion to *not overthink* things - once you get into a rabbit hole there's no predicting where it can lead.
Great video. Thanks.
Wonderful video!
This explains it clearly. I appreciate this information. Thank you.
This video is very sharp!!! haha 😆🤣😂 (sorry, I could not resist) Thank you for the info, I'm sure this info can remind some of us to focus on the bigger things and not sweat the small things so much. I know that this is what I'll take from this video. Take care and have a good one, Adios! 🖐
Love a good debunking video
Interesting. Thank you.
My reason for hollow grinding is that you can micro bevel the edge more times without having to fully hone the entire edge because the hollow removes the material that would be in the way with a flat grind. Depending on your micro bevel you can do four or five touch ups without having to grind or stone the entire surface. Never had a problem with a weak edge, that's your steel quality.
I sharpen my chisels on the left side of a Unicorn's horn. Then strop them with a Moth's wing. 😏
Heretic, everyone knows you're supposed to use the RIGHT side of a unicorn's horn for superior sharpening.
😂😂😂😂
Which wing?
@@MarkMcCluney Luna or Cecropia?
Liar, all the unicorns flew to Venus fifty years ago!
Well structured, interesting presentation, as usual.
Very good video
I am trying to find your video on the special addition chisels. Really want to order the box set. THANKS, Tom
Perfectly explained, thanks for the great content.
I have nothing to say really, but I appreciate your content, and wish to help with the yt-algorithms.
Second that
Great video! You are a far more precise craftsman than I am, and generally your type come off as pretentious an impatient. But as has been stated previously, you used logic, without patronizing, and it’s appreciated. I’ll subscribe, and check you out.👍🏼
It’s always nice to see how in depth you go in your videos. The information you present always have very informative information that makes sense. Speaking of stones, who do you recommend buying stones from. I’m looking for diamond stones.
Trend amzn.to/3d7vQaC This video explains why in detail: th-cam.com/video/zBND6emsSE4/w-d-xo.html
Thank you for the common sense brought to woodworking...especially when it comes to sharpening. I’ve hollow ground for years and frankly, when free hand honing on a flat stone the resulting bevel could be anywhere within 4-5 degrees. Big deal. Still works great. And +1 for Woodworkers Wonders. Love my CBN wheels.
great video thanks for sharing
Clear analysis based on data. Thanks!
I definitely appreciate this video. Always thought till now that it just made the edge to weak and thin
Love it! I have been meaning to sketch up in CAD just what you presented for some time. You saved me the trouble. My assumption has always been exactly what you presented. I don't currently use a quality wheel to sharpen my tools, but have been considering getting one to establish the initial edge on new cutting tools more quickly. (all new tools need it) I plan to stick with my tried and true diamond stones for maintenance. Thanks.
Thank you so much for this! I definitely fell for the exaggerated drawings!
Enjoyed this episode, thank-you.
Excellent !
Thanks again for another clear and interesting video. As we in the Netherlands say to people that enlarge problems that in reality make not even the slightest difference "ant f**kers". They're kind of right in the exact circumstances, but it doesn't matter. I actually sharpen some of my chisels to a 40 degree angle, these are for chopping. I found out and was taught in school the sharper the angle the sharper the tool the more you sharpen them, if that makes sense. But anyway, thanks for the confirmation, love the channel. Keep up the good work 👍
Nice to know, thank you. For me the sharpening time is a time to chill out and reflect but then I'm not trying to make a living with woodwork.
"Stool sample" "see their point" Stumpy Pun's
You and your fancy science, facts and common sense.
Very interesting! I think I agree! Always learn something, thanks.
Sanity is always good to listen to. My only reason for sticking to a flat bevel is that I tend to be a little heavy handed, and just a touch too much of that and my edge can turn blue. But them, I have never used microbevels either. I probably sharpen a little more frequently but I don't have any way of telling. No one else uses my shop.
Thank you… much vindications I am feeling!
-Borat (maybe)
I recently cleaned up some vintage Sweetheart 750’s that belonged to my grandfather and father before me. They had clearly been hollow ground at some point in their lifetime so I followed suit on my Tormek and proceeded to finish them with a 30° microbevel on an 8000 stone with a Veritas jig - stooooopid sharp. Had some guys making me feel like a jerk or that I had ruined them by doing that.
Certainly glad I’m the only one who has to be happy with them 😉
Perfect explanation. Keep up the great content.
Thanks, James. Great explanation as always. I’ll second your comments on Woodturners Wonders and the CBN wheels. Those grinder wheels have made a huge difference in my edge maintenance routine. And WtW is a great company. :)
Hard to make this point without drawing a picture, but if you hone just a little bit even without making a secondary bevel the angle at the cutting edge becomes parallel to the line drawn between the two original “corner points” anyway. So, the reduction in angle at the cutting edge that comes with hollow grinding instantly disappears when you hone.
I go from Tormek to three or four flat surfaces of wet or dry. I end up with, at least, 1/16 of flat area at the bevel edge.
I’ve been convex sharpening my irons and chisels for years thanks to Paul sellers. Used to hollow grind but it’s a pain and doesn’t get as good of results in wood. No idea why exactly. Maybe it’s just me.
If i remember correctly, Paul Sellers said: sharpen whatever way you like, i just happen to do it like this. So whichever way you do it: it’s all good :) And if you happen to like the convex way, all the better! You sharpen your tools and thats all that matters 🤩
@@samponette3306 though that is true, I don’t recall claiming, and a cursory glance at my comment confirms, that other methods of sharpening are worse than convex sharpening. That said, Paul sellers seems to be a man of very little ego. I don’t think he would ever push something on someone, he just shows his methods. Those methods likely are superior to others as his methods are the legacy of people who used to sharpen and grind irons literally all day. 🤷🏻♂️. Doesn’t mean hollow grinding and other such methods don’t work, to be sure. But I watch guys waste a lot of time doing something that takes about 30 seconds. That’s all.
@@asdqwe4468 exactly. And he gives great advice on how to find and use tools people once thought we’re obsolete. Now, I’m pretty sure he’s responsible for the massive hike for old plane and old woodworking tools in general but hey, they’re still affordable and that just means lots of people are getting into woodworking. Really like Paul and stumpy is also one of my favorites because of the huge breadth of knowledge and topics he covers.
Thanks for sharing those tips!
Seriously, I never knew. Thanks.
Great job from a great MAN
Oh boy, those unplugged woodworkers that did an internship with a family of beavers in Sasaskugwan in the 80’s are going to have a thing or two to say about this!
Good, um, points. I got something else out of this, though. Being relatively new to this practical sharpening thing (for decades, I just held my knives and other blades at what I thought might be the right angle and never got anything really sharp) where you start the process at 25, or 30, or 35 degrees on a grinder or some kind of metal wheel, depending on who is doing the video, then switch to a file, or sandpaper, or an oil stone, or a stone with a little water on it, or a water stone soaked in water, or a ceramic stone, or a diamond stone, and start with 80 or 120, or 150, or 300 grit, then keep using finer grits until you get to 600, or 800, or 1000, or 10,000, or 16,000, and then go to whetting or stropping or something on leather with white, or black, or green "stuff", then smooth leather. Doing all this in 30 seconds and you can have a scary-sharp edge to shave your arm hairs with. Here is the thing: I always had the notion that when you graduated from the grinder to flat surfaces, you were supposed to grind (or whet or hone or something) the hollow down until that surface was flat -- which takes just this side of forever, especially with a wide plane iron. So I just learned that it's just the end or ends of the arc of the hollow that need to touch the file/sandpaper/oil stone/stone with water/water stone/ceramic stone/diamond stone! Three cheers and thank you! Now my "30 seconds to scary-sharp" might only take a few hours instead of all day!
With the effective cutting edge of a blade (ANY blade) coming from a hollow grind, until you're effective angle results in something less than about 15 degrees, any thinning that might seem a disadvantage in metal loss, is compensated by the slight thinning allowing that blade's "wedge effect" to not have to pry so much material so far apart as the "intended angle" (the prescribed angle or that angle you've set the tool rest for on the grinder)...
There are few exceptions, but mostly those are a matter of the steel itself, the hardness being sufficiently beyond what was prescribed for the tool and process intended that it's either too soft or too brittle for the job and utensil in which it's intended to be used...
As mentioned in the video, there are those who will argue this all day.
I'm merely stating years of experience and observation APPLYING blades to stones, wheels, and other ablative instruments and then TO WORK...
To illustrate more simply... A common "prescribed angle" for a chisel is about 30 degrees... robust enough to be pounded into wood at any working angle with a mallet, but sharp enough to effectively cut through OR separate fibers in a reasonably clean and efficient manner...
For finer work, say the precision inserts of darker wood for pupils in the eyes of a predatory large cat for a hand-carved relief... This same blade can effectively be used with a grind as sharp as 20 degrees with few ill effects. The metal is sufficient to take the steady drumming of a mallet sufficient for such fine work AND it allows the craftsman to control the cuts for such tiny details,.. Again, below 15 degrees and a distinct "weakening" will be noticed in more frequent chipping at the cutting edge and mushrooming in shorter terms as well, should the chipping not be as present...
Just as the video suggests, the prescription handed down over centuries to present day wood workers is "AROUND 30 degrees"... BUT we (the new generation and future generations) absolutely MUST remember that most of these tools were developed in some form or fashion before there was such an invention as degrees for measuring angles and circles in the first place. They'd been developed through the same evolutions of trial and error that almost everything our society was built upon... The number of degrees was adjusted by feel and the basic trade-offs were always there...
A bulkier, higher incident of angle at a cutting edge IS more robust, longer lasting, and requires less maintenance at every term (short, middle, long) of use... The thinner, lower incident of angle will require more maintenance as it wears more quickly, but is easier on BOTH the craftsman and the tool, itself, to force through material and extracting waste.
SO what can we develop from this???
Each individual craftsman has some personal responsibility to find his own answers from the materials given in his shop... It's a balance from the supplies and qualities of steel in the blades he uses, and the particular crafts he engages in, and woods or other materials he uses, to explore his own form of "The law of diminishing returns". At some point, the amount of time and effort to upkeep blades is just short of the returns in work and convenience for using his tools to get products finished and out the door, from whence he expects his benefits or pay.
I would suggest fiddling with all your blades. I've used quite a variety, myself. For some things, like planes which you press by hand in steady strokes, a thinner hollowed edge can be a benefit in the ease of use. For others that vibrate (like a saw) or get struck outright (chisel?) the bulkier angles can benefit in the longevity under abuse. Each tool in any shop has it's own entity of purpose and maintenance. Each craftsman has an individuality in his style and methods.
Don't be afraid to be a bit different... AND don't be afraid to disagree with me, either... ;o)
Now you will have scores of people looking for new mole hills to mountainize.
Great explanation of this pro/con debate. Myself, as long as l get a razor sharp edge that lasts l am happy. I am also a believer in the micro edge due to a Rob Cosman video. Keep your very informative videos coming they are excellent.
The purpose of a micro bevel is to make sharpening quicker. When Rob Cosman, or Stumpy in his videos, demonstrates creating a secondary bevel, it's always in the context of moving to a higher grit stone. So, Rob demonstrates using a 300-grit stone to establish the primary bevel. Then, when he moves to his 1000-grit stone, he lifts the heel up just a little to establish a new, smaller, bevel -- the secondary bevel. As he has explained several times in his videos, the whole purpose of doing so is to avoid having to grind the entire primary bevel at 1000-grit. It's a time saver. Then, in Rob's case, he moves to his final stone and, again, raises the heel just a little more to establish a tertiary bevel. The reason is exactly the same -- to save time by avoiding the need to sharpen the entire bevel (primary or secondary) with his highest grit stone.
I love hollow grinds ... The grinder makes creating a fresh primary bevel so easy and fast rather than having to spend half a day on a coarse stone ... I just use a simple 6 inch cheap grinder with a normal aluminum oxide coarse wheel .. never had a problem of burning the steel .. at first when i got the grinder i was afraid from heat build up , but thats another area where people make a fuss about ... Run a few light passes at a time and feel the chisel/plane on your hands and you should be fine .. i dont even dunk in water and everything stays cool if you keep light pressure
thanks
Good points.
You are brilliant!
Five and a half minutes in and I am grinning ear to ear. Life lessons from the woodworking bench: whatever next? Thanks so much for this little gem. :-)
Point well taken!!!!🤔🤔😃😃😃
Do you have tutorials on sharpening my turning tools? I have gotten a little rusty great video! Learned something new like always
Thank you, thank you.
Great illustrations and explanation. I knew I was missing something important - the practical difference when using a secondary bevel is effectively nothing. Somehow I was thinking that my hockey skates are hollow ground and I certainly won't be skating on my chisel blades. I know, irrelevant, but I'm a newbie and want to really get this. Now I have no excuse to not find a proper rotating disk machine for the wheel you suggest. Would you use the same method for your marking knives? Also I'm still extremely glad for your post re the chainsaw blade on an angle grinder. Thanks again. Cheers
So does it cut? Trig sometimes works...other times, it has to just work for YOU. You have to make it work for you - not launch the Space Shuttle. Thank you for once again bringing this back to reality!
Nice explanation. Folks freak about cutting angles. Do you think any of this would have been relevant 100 years ago, 1000 years ago? Sharp is sharp and each worker would work with what he had. Working the cut with the angle he had ground. The fact that we can now measure "stupid" variations is just a distraction.
Personally, using precision in my angles ables me to eliminate variables in my sharpening, so that as a beginner sharpener, I'll get good results quicker. I see them as a crutch to get me woodworking with sharp tools quicker, but I hope that overtime I can become free of that crutch
100% agree the angle is not the issue. It's the repeatability and time it takes to get to sharp. Schwartz has an article where he sharpens everything to 35 degrees not because 35 degrees is an all important angle. But it allows him to sharpen at the same angle repeatedly. That's important when using a honing guide because it is very difficult to hone at 35 degrees once and then at a lesser angle in the future. You have to remove a lot more metal. Again its not the absolute angle its just that the angle is not less than what has already been used. But like you said most masters do it by hand and their muscle memory is probably as good as a honing guide
I agree.
@abom79 , i am sure you have practical experience with metal maybe what do you think?
Common sense. Always good to have.
Hey Stumpy! Everything said is definitely truth, but I much prefer a large bellied bevel (the opposite of hollow grind) I find it much more control-able for bevel down work and much easier for scooping out waste. I suppose the hollow grind is much more suited for maximum sharpness and bevel up pairing work. Since you've been taking up so many controversy topics you might try a shootout between bellied bevel (Paul sellers style) vs hollow.
Great videos! Something I could not get! How to get a grinder table to the proper angle on a 8"wheel to grind a , let's say, a 30 degree grind?
th-cam.com/video/BpdzXe8UBik/w-d-xo.html
You are right on the point with hollow bevel. Aren't the one that criticize it the same that will tell you to hone your chisel/plane blade to a precise angle that depends on the wood, the weather conditions and your date of birth for perfect results ?
I have met people arguing that a "Hollow Ground" is superior to flat bevel on the basis that the curve helps clearing chips. It doesn't make any sense to me. Any comments?
So the question remains Stumpy do you sharpen your chisels on CBN wheels? If so do you follow up on a 1000 trend diamond plate? Do you go higher to say 16000 stone?
If a tool needs extra work to change a bevel or repair a chipped edge, I grind on CBN wheels. Then I hone either on the Tormek, or with stones. If I use stones I start with 1000 grit diamond, then I strop with leather and paste if I'm in a hurry. If I have a little more time and want a very sharp edge, I go from the 1000 grit diamond stone to a 5000 grit Shapton ceramic stone, then a 16000 grit Shapton........ Frankly, I have to be comfortable with a lot of different processes because my audience has different needs and preferences, and I make videos for all of them. :)
I like when James finds a topic he's tired of people bickering over, breaks down the science of the argument, and essentially tells all of these people to STFU already in the nicest way possible.
I gave up trying to sharpen chisels... When they get dull, just buy a new one! Keep tool makers in business!
I need a diamond wheel !!
I mostly work with softwood and rarely go beyond 4000 grit. It works well for my needs. Sharpening is not complicated.