Excellent description of backlash Joe. That should clear it up for a lot of people. I am raising two grand kids and home schooling them, I have purchased my first lathe a Grizzly G4003G, You have just become our shop teacher I have chosen to go manual with no DRO to hone their math skills, nothing replaces real world hands on experience. My kids are 14 year old girl and a 15 year old boy, they are looking forward to learning the in's and out's of being a machinist. I have a son in law that is a machinist, so we have a go to guy at the ready but your video will be like Gold. Thank You Robert Miller
Thank you Robert. Stress safety first with the kids. Do it right. Make sure any long hair is tied back and never touch a moving machine until it stops. Don't forget steel gets hot when you cut it, so tap on a part you just cut before you grab it. Get them a trig book and have some fun with geometry too. Good luck to you all.
Safety is always a top priority , I have an industrial background operating and building equipment and your advise is well taken, it doesn't take but the blink of an eye for things to get very bad.
After almost two years of watching machinist teach machining, I finally get a really good explanation of calculating backlash. I have no DRO and an older machine. Yo. There is backlash, but I haven't known how to calculate it before now. I am ordering an Indicol. And, I would love to have a daughter that would immortalize me as a Lego figure. Congratulations on being part of raising her to do something so meaningful for you in return. Excellent video and much appreciated here (I'm in Nuuk, Greenland).
Thanks Jim. I'm glad I helped to turn on the lights for you. I will keep that lego guy forever. Great gift. And the fact that she got him in a captain america suit says a lot. So.....One way to never have to worry about that backlash is to always turn your dials in the same direction to make your move. It takes some thought, but after a while its second nature. Thanks for checking in.
Joe this is by far the best most informitive video you have done so far. I learned a lot and I do appreciate you showing us tricks to make things easier.
Thank you Joe for taking the time to explain in a clear and concise manner. Always a pleasure to watch your vids. Have learnt loads from you. Thanks again.
If you keep this up you will take over all the others and become the best resource for machining education on all of TH-cam. You're definitely putting out the most good stuff right now anyway, and that is no small feat. Thank you for the work and consideration you put into your videos. I should have my mill within a few weeks (my lathe and surface grinder have been lonely), so I'm excited to put this to work. :)
Great video. I have been doing machine tool rebuilds and retrofits for several years and you did a great job explaining the backlash of the screw/nut. There is another factor in backlash which is the bearing assembly that controls lateral movement of the screw, sometimes this is where excessive backlash comes from and can be easier to cure than the screw/nut assembly. Thanks again for great videos, they always make me think and have made me better at solving strange setups.
Another great video - thanks. Another quick and 'dirty' way I learnt was to eyeball the centre as best you could in one direction - say X - edge find then move in 1/2 diameter, then repeat for Y. Then repeat for X, then Y, etc. It gets you closer to centre with every repeat and even starting from a long way off after 3 or 4 repeats you're extremely close to centre (usually good enough if you're using an edge finder on round).
I just brought home a Bradford lathe. Ive been watching your videos and you inspire me to think outside. use geometry, and be precise. With thought, anything is possible. Thanks for sharing your creative side.
Nice video--I like your teaching style. My machinist days are a distant part of my checkered past, so these days I dream about machining stuff while watching videos like this. I had never thought of actually measuring the backlash. In times where I needed to account for it I would lock the table and spin the crank the other way until the backlash was gone, so the index ring was hopefully showing the measurement sans backlash. Come to think of it, I was constantly flipping those locking levers up and down to account for backlash. I wish we had had DROs--they must make things so much easier. For the problem at hand...I would have reached for the dial indicator.
Joe Thanks for spending time getting us "garage shop" guys up to speed on center finding!! You are a great teacher, Thanks again, Mark from northern MN
And that is exactly why I bought a DRO, even a brand-new machine has some backlash. It can be minimised to a negligible amount, by using high quality ball-screws, but they don't come free either.... I used nothing but the regular dials and dial indicators for about 15 year, but once you savoured" the blessings of the DRO" you won't want to be without one. Even the simple and cheap digital depth gauges on a pillar drill save a load of time (those are basically a digital caliper without the beaks) Great video man, great video indeed. It is a very good reminder of how to do things the 'proper' way. I made me one of those Indicol style holders, since they are as rare as hen's teeth in these parts.... they seem to be a particularly American style holder. They are a very handy addition to the shop though, and I wouldn't want to be without one, despite having a DRO on the lathe and the mill. The postage from the US is often prohibitive, a pity .... Thanks Joe ! Toodles!!! Paddy
Excellent explanation. I will practice this just for the experience of learning how to do it. I have DROs on my machine so I don't always have the need to pursue other approaches. Thanks for sharing!
Thinking back to my shop days, I think we used to call that "slop". As in, "watch out buddy, that machine has about .020 of slop in it!". I can't seem to recall how they showed me to account for it though. That was a looooong time ago! As always, great vid!
I still call it slop. Backlash is just the technical term because someone would undoubtedly call me out on it if I called it that online. Thanks for watching.
Seems to me "slop" is a bit less useful when thinking about precision, (which requires thinking precisely) because it could refer to movement due to loose or worn dovetails or other guideways, or to the combined total of backlash and angular play due to guideways.
I did establish the backlash on the Rockwell long ago but I do not rely on that. Backlash is different at different places of spindles. Therefore I add to your great video: each time one uses backlash figures it should be re-established for that position where the work is done.
Thanks Joe, very in depth exercise in backlash and indicating. Good to go over this kind of 101 stuff that either you don't know or have not thought of for a long time, makes you think a little, and thinking is good.
Finally got a DRO for my machine. While watching and understanding your video I had the though of putting a good scale in the vise with a pointer in the quill, setting the DRO at the start and moving it like you showed for results. This would also confirm your math. Thanks, again for the information!
Wow Joe, another great tutorial, thanks for posting it. Now with regards to your 0.033" backlash on the Bridgeport X axis, ever so simple to adjust out. Means bending you back and a large flat bladed screwdriver, but it will literally only take 5 minutes to adjust. To save me going into great detail describing how to do it. Have a look in the manual if you have one, if not try looking on TH-cam to see if someone has done a video. I may have a look myself in a while and if I find one I will post the link here. Well done again for super explanation of a common operation. Here is a good link on how to adjust the backlash, hope it helps. He does not show or say how to do it, so here is a quick description. Slacken the small locking screw, tighten the large screw just enough to take up any backlash, check the whole length of the lead screw if possible in case it is badly worn in one spot. When you are satisfied with the fit, re tighten the small locking screw. th-cam.com/video/X3cRLlFrdkg/w-d-xo.html
Fantastic video on backlash. I thought I knew what backlash is but got a better understanding. I am looking forward to chewing on this a while and playing with the dials. Something new to learn every day. Thanks, Joe. I look forward to your videos. Bill
So glad I found this video!! I took some night classes on machining and learned on a DRO. I've been struggling with the backlash for a couple years and finally decided to get the DRO. Now, I can ensure my key slots are on center as I also add a power feed, and have to create adapter shafts to take up the difference between my X-axis feed screw and the power feed's inner bearings. It's gonna be real nice having a DRO and Power Feed on my old Clausing milling machine!! Thanks again!! 👍
So, once I found my backlash in both axes it got me to thinking about something. What happens if I use my (now KNOWN) backlash to reveal the extra distance I had to move the table (as measured on the dial) to eliminate backlash altogether, as opposed to having to calculate its distance?? For example, let's say I'm turning my crank handle in one direction (having eliminated all backlash) prior to touching off on my part. When I touch the part, I know the table's nut is traveling along the acme thread in that direction. Then, I zero my dial prior to continuing in the same direction (lifting the spindle, first). Now, as I continue to move my table in the same direction until I am PAST my part (counting the dial rotations - I should already have a rough idea of the diameter as measured with a micrometer.), then as long as I continue to move the table the distance of the radius of my edge finder PLUS my now KNOWN backlash PLUS a little more (for safety), then I'll be assured that when I reverse the rotation of my crank handle the table's nut will be resting on the opposite side of the acme thread before it touches off the part in the opposite direction!! By adding at least the edge finder's radius PLUS the backlash PLUS a little more to be in the same side, then when turning the crank handle in the opposite direction, I will ensure the backlash was fully removed prior to touching off the part from the opposite direction. That's probably why I've heard it said to go a full turn past the other edge of a part BEFORE reversing the crank handle's rotation. Because, it assumes you're NOT FAMILIAR with a particular machine's backlash. As a result, going a full turn makes it easier to remember where you touched, and ALSO is beyond the backlash of even the loosest machines. Sorry if this was said somewhere else, but I didn't read all of the comments. Just trying to get my DRO on ASAP!! LoL
Just found this video Joe, thank you, I've recently had this very issue, having no dro on my milling machine, as always your solution is simple and efficient
Thanks Joe, great tutorial, also good to see your videos improving with each one as you get more comfortable in front of thr camera ... and a belated happy birthday!
Lots of good stuff, as usual. The question I have every time I watch a video of finding centers of round stock is “why not just measure the diameter and divide by 2?” I normally have the set side of the vice set at zero. So if I move the y axis half the measured diameter, it is now on center that way. Now I only need to find the edge going one direction on the x axis. Backlash is taken out by only moving one direction.
Joe Pieczynski. This was not a challenge, just a question. On the job training to learn machining before digital readouts puts my thinking on a different track. I often wonder why people using the DRO do the things they do. Maybe easier, maybe faster? My point is that it is easy to get the x axis on center. Hold the stock with a “V” block or whatever, you know the distance from the set jaw to the center, so you know where to set “y” to center the x axis. Now approach the part from either side to find the edge, punch some numbers into a calculator and you know where to move “x” to set center. I like the little device that holds the test indicator. Simple and it does not require removal of the tool. I have one, but don’t always trust it to be sturdy enough. That is because the way we did it circa 1970 was to put a .375 diameter rod in the collet that had been formed to a 90° bend. That system was rock solid. It was also clunky, so pick your poison I guess.
@@dougberrett8094 No problem. If you already have one side or edge established, your method is perfectly sound, and probably quicker. Thanks for the follow up.
I agree, find the centre of the fixed jaw of your vice for instance, using a piece of ground stock or a parallel and moving vice backward towards the machine head; then continue moving half the diameter of your round stock, lock the bed off.
Thank you Joe for another excellent presentation! I've been using the indicator method for a long time and the DRO method for several years and truly enjoy your refresher! No matter how one goes about doing a certain procedure, it always is a refresher to watch your explanation on how to go about it! Thanks for sharing and keep up your great work!
Thanks Joe, I'll be watching this one many times. I actually a dial indicator but I don't have the test indicator type like your B & S. I also will be looking for the indicator holder like the one used in this video.
Excellent information, I to have a DRO and have grown lazy (smarter?) but it is always good to review the basics. I think this basic understanding will help you in all your setups with or with out DRO or dial indicator. Great video
Hi Joe, when I use edge finder on round stock, I make sure the edge finder is slightly below center, pick up the center, then post .100 on my "Y" reading on DRO, or if no dro, set my dial at .100, then measure the rod and divide by 2 and move that amount, no calculating or errors. Same with "X"!
Excellent video as usual. If I wanted to know how much backlash I had, I would probably just turn the crank one way to the zero, lock the table while still at zero, and then spin the crank the other way until it stops and read the number off the crank. I'm sure there is some finesse missing in this approach, but it seems like it ought to work. The DRO was one of the best investments I ever made--the installation process is highly customized to your own machine and takes a month of Sundays but it's worth it. Always knowing the absolute position of the table is an amazing thing and we take it for granted.
Most machines more than a few years old, depending on how much use (or abuse) they have seen, can have markedly different backlash values at different positions on the leadscrew - almost always more in the center (where it gets the most use) than at the ends. My old Clausing has about 0.005 at each end and more than 0.020 in the middle. Over long distances that wear can affect the accuracy, too. This is precisely why I had to get a DRO for my machine and now never even bother to look at the dials any more. I know - you're thinking it's time for a new leadscrew, but I've seen this phenomenon to some extent on every machine I have run in my 55 years as a machinist, except maybe a few new or almost new ones. I learned, as you probably have too, that the indicator is your most valuable and precious tool. (Jo blocks are next in line for the title).
Thank you for this. Some of us are just learning in the home shop with an old fully manual drill mill. Mine is a Jet-16 bench top 8 speed. I’m not even sure how old it is, 1980’s or possibly older.
Yet another thought provoking video Joe, which I understood very well as I used to teach high school metalworking / engineering here in the UK and had to explain the theory of backlash to the students. this by the way was long before the advent of digital readouts, when digital meant doing it with your fingers! This was extremely well explained, once again thank you.
Joe, I must apologize in the first one your videos I watch I said something to the effect of camera was a bit on the bouncy side I was wrong, sorry. I am interested to know what type of camera you do use though. I want do a video on gear cutting which is one of big things we do in our shop. This video was one best the explanations of backlash that I have ever seen, you took an issue that every serious machinist has to deal with on much a weekly basis if not more, got to the basics to application clear, concise and timely fashion. Another hit, keep 'em coming. Cheers, Doug
I use a GoPro Hero 3 and a nikon b500. The Nikon is for the super close stuff and the go pro is for the general shots. You can tell which is which by the fisheye effect the GoPro has.
You CAN find true center with just the edge finder, no DRO, on a machine with unknown backlash. You find the edges left to right then right to left. The difference is the backlash. Split that and you are on center. This works on round and square stock.
I appreciated your responding to my comment.I would suggest that you might consider making a video on the best way to machine a rectangular block. I have seen some videos on machining blocks which are about 1" square. In the real world you need to machine parts of bigger size.It amazes me that I have had people working for me who were in the business for a number of years but did not know the simple operation of squaring a block. They use a machinist square, a level etc. In a job shop you try to develop good habits that produce consistent results. You try to do things by the best method in the shortest amount of time.You might find this of interest. I noticed that you are wearing a Ruger shirt. My nephew was living in Chicago with a woman who has heavily opposed to owning guns.My nephew divorced her moved to San Antonio and is engaged to marry a Texas Gal. I told him that if he moved to Texas that he had to buy a gun, get cowboy boots, and purchase a Stetson at Paris Hatters.In one year David presently owns 8 handguns, a pair of boots, but has yet not purchased a hat. I am going to his wedding in San Antonio in April and he has arranged that after the wedding we go to a firing range. Seems appropriate.Again you make great videos and I would encourage anyone who is interested in this trade to watch.Charles
The backlash depends on the measuring position of the table. In position where it is most used (Centre of table stroke) the backlash would be bigger than at the end. Very good film and great explanation od the problem!
Another great video Joe,, hope u realise what a fantastic help you are 2 all us newbies out here. Have watched ALL your videos.. well.... except for the bloody spider one EEK!! LOL keep them coming mate. Still don't get the one on using Trig angles on the compound. :) That's my fault though... not yours! I will go back and watch it another 2 or 20 times till I get it. You have got me addidcted... i spend more time watching your videos than I do out there on my machines... LOL
There are other ways to do this but it is your show. Thanks for doing this as there is a ton of misinformation and poor practice on TH-cam, As for backlash you can take up slack and re-zero the dials.
For sure. This video was posted as a courtesy to a very specific viewer inquiry. The theoretical and practical demonstrations are accurate and fairly broad in their scope. Not all machines have adjustable bronze nuts capable of reducing or eliminating backlash, so this level of information is very useful. I do appreciate the feedback and comment. Thanks for watching.
I would be very interested to hear your technique for calculating an accurate backlash value. Feel free to respond and share your thoughts when you get a minute.
Tried to post this and the comment is highlighted and cant post my reply. Will try here. I compare my feel for the dials with a dial indicator. Is your businesses contact you email contact. Worth
Nice explanation Joe, thanks. I agree, a dial indicator is way more accurate than a traditional edgefinder. I've played around with lasers and ultrasonics, but nothing beats a dti, even a cheap Chinese one!
I concur with "get an indicator." My century old lathe has more wear in one area of the cross slide feed screw, as many (most?) of them do. If I happen to be working in that transition zone from 'more worn' to 'less worn' the reading according to the cross feed dial will go off. Frustrating to take the last .010 off of something and discover that, on that last pass, you actually took off .012, turning the snug fit you were going for into a floppy fit. And it's nice to see that I'm not the only one that believes in using match marks.
Hello Joe. Another great video, as usual. In regards to backlash, you mention in the video that it will be a constant we can measure on our own machine, and keep that number for reference. My question is, wouldn't the amount of backlash on an older machine be larger near the center of the lead screw, where the most wear has taken place, as opposed to the ends? Or do you think this difference should be negligible, provided the machine isn't completely worn out? What do you consider acceptable maximum for backlash on a manual knee mill, i.e. the point where the mill should be repaired, or replaced? Thanks.
I would expect older machines to be worn more in the center than the ends. 20-30 thou of backlash isn't necessarily a show stopper, but when you adjust it out correctly and the machine travel is restricted in some areas, it may be time to get it rebuilt.
Joe, you really earned this up vote. Excellent video. I have a question about edge finders. I've spent some time in a machine shop, used an edge finder quite a bit, and seen lots of guys use em, but I've never seen anyone use the other end (the pointed end). What is it for?
Thanks Joe. Good information. I do have a DRO but did the exercise to see what my backlash actually was. Also, I have an Indicol knock off and didn't know it had the dovetail tapers, took it out and sure enough, another way to hold the indicator. May use it more now. Doug Edwards
Great video... I could be wrong here, but if you have a DRO on your mill it shouldn't see the backlash because it only keeps track of the actual movement of the table. If you only have the micrometer collars then you will see it because they are attached directly to the lead screw of the table. I never notice the DRO reading change when I reverse the table until the backlash is gone. I guess you can check by just turning on the DRO and wiggling the handle back and forth and watch. Just a thought.
You are correct. A DRO erases all this worry. This video was shot in reply to a non DRO user wondering how to calculate backlash and compensate to find edges and centers.
Hi, I've only just found your channel... Great vids! I'm more in to the welding side of things, although I do appreciate the good machinists channels too, well done.
Thanks. I do have great welding equipment here, but I don't have the polarized lenses for filming that kind of topic. I'm not talented enough to compete with the other guys on this topic either. Maybe someday.
Excellent tip. Does it matter what spin direction we operate the edge finder is? Example assuming we start on x axis with x1 by the west end of stock, also we have no idea how far south (for instance) x1 is below the center line. Such condition, the probe can be more sensitive in one direction of rotation than the other. If unsure please run an experiment to rule this in/out. If proven that make difference we can always use up CW on x1 and CCW on x2 such that the probe always roll up hill against the stock. This can remove the uncertainty caused by x1 and x2 start indicating south of the center line. Please ask me questions to clarify my words.
Joe, I really like the way you convey information. I do have a question however about finding the edge of a piece of round stock. You covered backlash, but what about the behavior of the edge finder when you are off center, I suspect a new gremlin arises and that is the spindle rotation. I think the edge finder is going to behave differently depending on how the edge finder sees the round shaft depending on spindle rotation and if you are above or below the center line.
You assumed that the backlash is a constant. But that is not always true. Although the screws wear more slowly than a bronze nut, they still wear. And they wear unevenly because there is a zone on the screw which is used more often than others. In such a case your backlash depends on the position along the screw.
I'm no machinist, currently at school for engineering, and working on a bit of an interesting project on my own time. How would you find the center of a threaded hole? Trying to take a flange with 4 evenly spaced threaded holes and add a pattern of 5 threaded holes, and the best way is to have one hole in common between both patterns. And vice versa on a different flange. Current idea is to use the lathe and make a concentric locating pin to thread in the hole and use a method like this to find the center of it, while the whole flange is fixtured in a dividing head. Locate, turn, drill, thread, repeat.
2 ways. Use pins in the holes and locate on the minor diameter, or use magnification and locate off the countersunk edge of the hole. if its a quality hole, the c'sink was done before the threads and is a good reference to find center.
bold of you to assume I have a machine shop, let alone a garage at my -parents- house, maybe in the future, I'm mostly here for practical fun. By the way, that LEGO Joe Pie has got to be one of the best things I've seen on TH-cam.
Hi Joe, thanks for all your excellent videos, I have learned a lot of new techniques. I have a question with respect to centering a disk that is mount vertically with reference to the mill table. I want to center a hole on the circumference the goes from the OD to the ID of the part. The disk is too large to use an edge finder. Any help would be appreciated, maybe you can create a video. Thanks, Dave
The backlash number will change on different places of the travel because we typically do lots more work in the center or where the vise is normally mounted than we do at the ends of the travel, so the lead screw tends to fit looser there because of increased wear in that portion of the lead screw. It's a moving target...
Its a good idea to move your vise L or R occasionally to spread this wear around. I alternate between the two I have mounted for just this reason. Thanks for the comment Bob.
Russ Hall I have a very old and worn mill and it seems to me that I might expect to find the backlash different at different locations on the screw. Most of the ware should be on the nut which would be fairly consistent through all the travel, but the high use middle zone of the screw might have more ware on it than out near the ends. If this is true, it seems that I should check the backlash where I am working on the screw.
I'm thinking that you might move your table out to the ends of its travel in both directions. Then, get underneath with a flashlight and check out the acme threads. Measure every third or fourth thread with some accurate calipers to give you a rough idea of where you should be looking for different backlash. You might find that the first inch or two the threads are like new. Then, they're about equal for another few inches, only thinner threads than at the ends. And, you find a big drop in acme thread thickness at some point. If you bought your machine from a company's private shop, then all of the work was probably relegated to a section of the mills table. Or, you could get an inexpensive DRO, and not even bother with what backlash you have and where you have to be concerned with it, to one degree, or another.
I read in an old machinist tips & tricks book that you can find center of round stock with an edge finder by touching off x axis move in rad of part + rad of edge finder then y axis move in the same, repeat 3 more times.
@@ronmccabe1169 it's not ideal but when you don't have the ideal situation, overly gated casting, dial out for calibration, or I'm to fat & lazy walk over to the toolbox it's a good thing to know.
Hi Joe, don't know if it helps or not, but when I indicate a round part in the vise, I pick the x side first, pick the minus side, go until I hit zero, and zero my DRO, then pick up indicator and turn to other side and pick up zero, then split the difference on the reading, then the same with "Y" and it will be within a couple thousandths right away, then its easy to zero out!
An edge-finder is not a good enough tool for round stock. Rounds have no edge that will contact an edge-finder squarely it has either got to kick out climbing up to the centre of the round or kick out running away from centre, never accurate enough. Dial indicator the easiest and more reliable than a DRO. very in depth vid Joe and well presented.
Cool, lego figure...I wouldn't mind if you adopted me joe...lol I hope she realizes how lucky she is to have a dad like u.....a lot of ppl don't....Thanx again for the video and info joe ...
All your videos are excellent, but I walked away still a little confused at the end of this one! It was the last part where you were back at the white board just before the end. You made the comment that you were going to give your ending comments just a little more thought. I didn't understand your comment just before you said that!
Unrelated topic but I have a question you can probably answer. My shop is an old tin can that used to have a leaky roof. I replaced the leaky roof but here in mid Michigan we have an issue with high humidity and I'll find something I've sandblasted or something bare metal that I bought new pretty quickly develops a skin of rust. What to you use on your ways, what do you use on your collets, clamps etc? I just bought a new indicator, stand and a set of collets and I'm afraid to take them out to the shop! LOL WD, would last very long but might be a perfectly good product. I'm a mechanic and don't really use my mill and lathe all that often. The tarps come off those when I need to make something for the drag car or when someone shows up with an "impossible situation" they want me to solve. It doesn't pay very well but the bragging rights are awesome! So I solve em.
When I plan to be out of town for a while, I like to spray down my exposed machine surfaces with WD-40. It has always worked well. I also used to own a jet ski rental business in NJ and always prepared my machines for storage by spraying the engine and drive system with marine fogging spray. Those engines looked brand new every spring. You could probably use either and have good results.
thank you keep up the good work I learned something, that is why why i subscribed, new to this and want to learn . I love the lego, my family try to support me in my new expertise . i try to be jack of all trades but this is new. Look for many more tips.
I have not pursued my thought but i often wonder if there is a variation in readings on round stock or internal bore readings when slightly off center due to rotational differences of the edge finder when approaching the part form opposite sides
I thought that as well. If it were a solid making contact, the tangent point would be a mirror image, so I would assume rotational influence would be minimal. Being as close to center as possible for the first leg at the time of contact by the edge finder would be highly suggested to minimize error.
Hi Joe. great gift from your daughter, thats serious cool lol. what id like to know: what to do when a dial indicator falls, is it totalled like you people call it in the states or can it be salvaged. using a edge finder to find edges and work my way to centre doing the maths
very informative Joe I liked this a lot but now I'm forced to ask,when indicating the part does that "slop" or "play" ever come into play on the "z" axis, z axis play I mean,thanks
Hi there, using a dial indicator to find the center, does just that, it only finds the center. All the play / backlash will still be there and if you need to offset a known amount from the center, you still have a problem knowing how much that is and in what direction i.e. cw or ccw. The only way to make real sure is to always take out the backlash in a known direction. When you have dialed up the center, set the indicator dial to zero, back away with the table handle and then come back to the zero from a known direction, and then set your handle dial to zero.. Sounds complicated, but when you have done it a couple of times, the procedure will soon sink in. As long as you always approach from the same direction, backlash is not a problem for setting dimensions, but it is a problem when machining. If you try to climb mill with a worn leadscrew, the cutter will crab and pull the work piece into it. Hope this helps.
Good points Dave. I try to always finish my position moves with a clockwise move on the dial. Either that or start at the back left of your part and work toward the front right. The table moves will always be clockwise moves on your dial.
Travis. I have to say yes to this question. Not so much for dimensional accuracy, but absolutely for machining rigidity under 2 special conditions. If you have ever tried to drill or plunge mill round stock on a round surface, you will notice a terrible bouncing between flutes leaving an awesome, but unwanted, chatter pattern on your part. By leaving some tension on your quill lock, or locking it completely and coming up with the table for the initial penetration, it goes away. Other than that, I really can't think of any other impact.
Wayne, your observations and comments are accurate. There are many conditions that may exist based on a hundred different variables. Naturally, if you intend to map out your machine, do it in your working envelope. I try to cover as much valuable material as I can while keeping the video to a comfortable watchable length.. How about shifting your vise off center for a year or two to work in a zone on your lead screw that may not be worn. Just a thought.
if you're not on center though ........with a kickout-centerfinder, one side it'd kick downhill. And one side it would kick up-hill. Wouldn't that influence the sameness of each point? At least if you start on center you always be kicking downhill. In other words the kick out would roll off the round part rather than climb up it. Anything to that? You could I guess turn your machine in reverse for the opposite reading. In fact that's the solution isn't it (if there is a problem)
Not exactly sure what you're asking. Regardless of where "off center" you are on a circle (assuming you're looking down on a "circle" vs a rectangle, or some other oblique shape), the finder will always hit the part tangentially from both side. The idea of using an edge finder totally eliminates any discussion of uphill vs downhill, because those terms are reserved for non linear flutes and approach directions to work. In addition, tools climb work because they're locked into a collet, or an arbor of some sort. The edge finder is designed to eliminate that, because it designed to kick out at the slightest touch. Again, uphill vs downhill doesn't even become a factor. It's all negated. Assuming your round stock is lying flat in a vise, or v-block (instead of on its end, as in video) means the edge finder will contact the round bar where it is sticking out farthest AND will contact the edge finder on its corner edge (The ONLY place where this won't happen is when measuring the exact center of the round bar.). However, even in THIS case, there is no twist to worry about, because there aren't any twisted flutes. And, as also mentioned above, the edge finder is designed to "give" at the slightest touch. So, again, uphill, downhill, conventional, climbing, etcetera are terms that wouldn't be used here. Therefore, NO, there is no influence being imparted by approaching the work from either direction by the edge finder.
Hey joe I know what you just showed on the backlash is to be true but if you know your machine you should feel the backlash and reset your dial when changing directions for most jobs
To find the center If you put a small rule on top of a round material using a small rule bring down a quail with a drill bit till the rule is level If you put a pointed scribe in the chuck then on the rule is the scribe method more accurate (smaller the point more accurate) ?
Novices should realize the backlash slop will be different depending on what part of the lead screw is used. The center is usually worn more than the ends- use a dial indicator.
Excellent description of backlash Joe.
That should clear it up for a lot of people.
I am raising two grand kids and home schooling them, I have purchased my first lathe a Grizzly G4003G, You have just become our shop teacher
I have chosen to go manual with no DRO to hone their math skills, nothing replaces real world hands on experience.
My kids are 14 year old girl and a 15 year old boy, they are looking forward to learning the in's and out's of being a machinist.
I have a son in law that is a machinist, so we have a go to guy at the ready but your video will be like Gold.
Thank You Robert Miller
Thank you Robert. Stress safety first with the kids. Do it right. Make sure any long hair is tied back and never touch a moving machine until it stops. Don't forget steel gets hot when you cut it, so tap on a part you just cut before you grab it. Get them a trig book and have some fun with geometry too. Good luck to you all.
Safety is always a top priority , I have an industrial background operating and building equipment and your advise is well taken, it doesn't take but the blink of an eye for things to get very bad.
After almost two years of watching machinist teach machining, I finally get a really good explanation of calculating backlash. I have no DRO and an older machine. Yo. There is backlash, but I haven't known how to calculate it before now. I am ordering an Indicol. And, I would love to have a daughter that would immortalize me as a Lego figure. Congratulations on being part of raising her to do something so meaningful for you in return. Excellent video and much appreciated here (I'm in Nuuk, Greenland).
Thanks Jim. I'm glad I helped to turn on the lights for you. I will keep that lego guy forever. Great gift. And the fact that she got him in a captain america suit says a lot. So.....One way to never have to worry about that backlash is to always turn your dials in the same direction to make your move. It takes some thought, but after a while its second nature. Thanks for checking in.
Very nice tutorial video. It makes me even more glad that i went to the trouble of getting a DRO. Keep on keeping on.
Thanks. I like mine as well. But this exercise shows us how we overlook the utility of our DRO's.
Joe this is by far the best most informitive video you have done so far. I learned a lot and I do appreciate you showing us tricks to make things easier.
Thanks Bill. It came out longer than expected, but it does cover a lot. I appreciate you watching and takin the time to comment.
Thank you Joe for taking the time to explain in a clear and concise manner. Always a pleasure to watch your vids. Have learnt loads from you. Thanks again.
If you keep this up you will take over all the others and become the best resource for machining education on all of TH-cam. You're definitely putting out the most good stuff right now anyway, and that is no small feat. Thank you for the work and consideration you put into your videos. I should have my mill within a few weeks (my lathe and surface grinder have been lonely), so I'm excited to put this to work. :)
Thanks for the comment Jon. I'm enjoying this. Good luck with the mill. Your capability just went up ! Have fun and watch your fingers.
Great video. I have been doing machine tool rebuilds and retrofits for several years and you did a great job explaining the backlash of the screw/nut. There is another factor in backlash which is the bearing assembly that controls lateral movement of the screw, sometimes this is where excessive backlash comes from and can be easier to cure than the screw/nut assembly. Thanks again for great videos, they always make me think and have made me better at solving strange setups.
Another great video - thanks. Another quick and 'dirty' way I learnt was to eyeball the centre as best you could in one direction - say X - edge find then move in 1/2 diameter, then repeat for Y. Then repeat for X, then Y, etc. It gets you closer to centre with every repeat and even starting from a long way off after 3 or 4 repeats you're extremely close to centre (usually good enough if you're using an edge finder on round).
I just brought home a Bradford lathe. Ive been watching your videos and you inspire me to think outside. use geometry, and be precise. With thought, anything is possible. Thanks for sharing your creative side.
Ps The backlash tutorial is invaluable. This Bradford has lash in Hundred thous. But im cutting metal.
Nice video--I like your teaching style. My machinist days are a distant part of my checkered past, so these days I dream about machining stuff while watching videos like this.
I had never thought of actually measuring the backlash. In times where I needed to account for it I would lock the table and spin the crank the other way until the backlash was gone, so the index ring was hopefully showing the measurement sans backlash. Come to think of it, I was constantly flipping those locking levers up and down to account for backlash.
I wish we had had DROs--they must make things so much easier.
For the problem at hand...I would have reached for the dial indicator.
Joe Thanks for spending time getting us "garage shop" guys up to speed on center finding!! You are a great teacher, Thanks again, Mark from northern MN
And that is exactly why I bought a DRO, even a brand-new machine has some backlash.
It can be minimised to a negligible amount, by using high quality ball-screws, but they don't come free either....
I used nothing but the regular dials and dial indicators for about 15 year, but once you savoured" the blessings of the DRO" you won't want to be without one.
Even the simple and cheap digital depth gauges on a pillar drill save a load of time (those are basically a digital caliper without the beaks)
Great video man, great video indeed. It is a very good reminder of how to do things the 'proper' way.
I made me one of those Indicol style holders, since they are as rare as hen's teeth in these parts.... they seem to be a particularly American style holder.
They are a very handy addition to the shop though, and I wouldn't want to be without one, despite having a DRO on the lathe and the mill.
The postage from the US is often prohibitive, a pity ....
Thanks Joe !
Toodles!!!
Paddy
Excellent explanation.
I will practice this just for the experience of learning how to do it. I have DROs on my machine so I don't always have the need to pursue other approaches.
Thanks for sharing!
Thinking back to my shop days, I think we used to call that "slop". As in, "watch out buddy, that machine has about .020 of slop in it!". I can't seem to recall how they showed me to account for it though. That was a looooong time ago!
As always, great vid!
I still call it slop. Backlash is just the technical term because someone would undoubtedly call me out on it if I called it that online. Thanks for watching.
Seems to me "slop" is a bit less useful when thinking about precision, (which requires thinking precisely) because it could refer to movement due to loose or worn dovetails or other guideways, or to the combined total of backlash and angular play due to guideways.
I did establish the backlash on the Rockwell long ago but I do not rely on that. Backlash is different at different places of spindles. Therefore I add to your great video: each time one uses backlash figures it should be re-established for that position where the work is done.
Had forgot about this after adding the DRO. Good video and explanation. Thank you
Thanks Joe, very in depth exercise in backlash and indicating. Good to go over this kind of 101 stuff that either you don't know or have not thought of for a long time, makes you think a little, and thinking is good.
I agree John.
What a great lesson 😃 Thanks Billy a nd Joe
Finally got a DRO for my machine. While watching and understanding your video I had the though of putting a good scale in the vise with a pointer in the quill, setting the DRO at the start and moving it like you showed for results. This would also confirm your math.
Thanks, again for the information!
Your videos are very educational and inspiring. Your an excellent teacher. Keep em coming
Wow Joe, another great tutorial, thanks for posting it. Now with regards to your 0.033" backlash on the Bridgeport X axis, ever so simple to adjust out. Means bending you back and a large flat bladed screwdriver, but it will literally only take 5 minutes to adjust. To save me going into great detail describing how to do it. Have a look in the manual if you have one, if not try looking on TH-cam to see if someone has done a video. I may have a look myself in a while and if I find one I will post the link here. Well done again for super explanation of a common operation.
Here is a good link on how to adjust the backlash, hope it helps. He does not show or say how to do it, so here is a quick description. Slacken the small locking screw, tighten the large screw just enough to take up any backlash, check the whole length of the lead screw if possible in case it is badly worn in one spot. When you are satisfied with the fit, re tighten the small locking screw.
th-cam.com/video/X3cRLlFrdkg/w-d-xo.html
Thanks Dave. I've done it before, but not in a while. I guess it would be good to reduce it a bit.
Fantastic video on backlash. I thought I knew what backlash is but got a better understanding. I am looking forward to chewing on this a while and playing with the dials. Something new to learn every day. Thanks, Joe. I look forward to your videos.
Bill
Thanks Bill. I enjoy doing them.
So glad I found this video!! I took some night classes on machining and learned on a DRO. I've been struggling with the backlash for a couple years and finally decided to get the DRO.
Now, I can ensure my key slots are on center as I also add a power feed, and have to create adapter shafts to take up the difference between my X-axis feed screw and the power feed's inner bearings.
It's gonna be real nice having a DRO and Power Feed on my old Clausing milling machine!! Thanks again!! 👍
So, once I found my backlash in both axes it got me to thinking about something. What happens if I use my (now KNOWN) backlash to reveal the extra distance I had to move the table (as measured on the dial) to eliminate backlash altogether, as opposed to having to calculate its distance??
For example, let's say I'm turning my crank handle in one direction (having eliminated all backlash) prior to touching off on my part. When I touch the part, I know the table's nut is traveling along the acme thread in that direction. Then, I zero my dial prior to continuing in the same direction (lifting the spindle, first).
Now, as I continue to move my table in the same direction until I am PAST my part (counting the dial rotations - I should already have a rough idea of the diameter as measured with a micrometer.), then as long as I continue to move the table the distance of the radius of my edge finder PLUS my now KNOWN backlash PLUS a little more (for safety), then I'll be assured that when I reverse the rotation of my crank handle the table's nut will be resting on the opposite side of the acme thread before it touches off the part in the opposite direction!! By adding at least the edge finder's radius PLUS the backlash PLUS a little more to be in the same side, then when turning the crank handle in the opposite direction, I will ensure the backlash was fully removed prior to touching off the part from the opposite direction.
That's probably why I've heard it said to go a full turn past the other edge of a part BEFORE reversing the crank handle's rotation. Because, it assumes you're NOT FAMILIAR with a particular machine's backlash. As a result, going a full turn makes it easier to remember where you touched, and ALSO is beyond the backlash of even the loosest machines.
Sorry if this was said somewhere else, but I didn't read all of the comments. Just trying to get my DRO on ASAP!! LoL
Just found this video Joe, thank you, I've recently had this very issue, having no dro on my milling machine, as always your solution is simple and efficient
Thanks Joe, great tutorial, also good to see your videos improving with each one as you get more comfortable in front of thr camera ... and a belated happy birthday!
Thank you.
Lots of good stuff, as usual. The question I have every time I watch a video of finding centers of round stock is “why not just measure the diameter and divide by 2?” I normally have the set side of the vice set at zero. So if I move the y axis half the measured diameter, it is now on center that way. Now I only need to find the edge going one direction on the x axis. Backlash is taken out by only moving one direction.
In order for that to work, you would already have to be on center.
Joe Pieczynski. This was not a challenge, just a question. On the job training to learn machining before digital readouts puts my thinking on a different track. I often wonder why people using the DRO do the things they do. Maybe easier, maybe faster? My point is that it is easy to get the x axis on center. Hold the stock with a “V” block or whatever, you know the distance from the set jaw to the center, so you know where to set “y” to center the x axis. Now approach the part from either side to find the edge, punch some numbers into a calculator and you know where to move “x” to set center.
I like the little device that holds the test indicator. Simple and it does not require removal of the tool. I have one, but don’t always trust it to be sturdy enough. That is because the way we did it circa 1970 was to put a .375 diameter rod in the collet that had been formed to a 90° bend. That system was rock solid. It was also clunky, so pick your poison I guess.
@@dougberrett8094 No problem. If you already have one side or edge established, your method is perfectly sound, and probably quicker. Thanks for the follow up.
I agree, find the centre of the fixed jaw of your vice for instance, using a piece of ground stock or a parallel and moving vice backward towards the machine head; then continue moving half the diameter of your round stock, lock the bed off.
Thank you Joe for another excellent presentation! I've been using the indicator method for a long time and the DRO method for several years and truly enjoy your refresher! No matter how one goes about doing a certain procedure, it always is a refresher to watch your explanation on how to go about it! Thanks for sharing and keep up your great work!
InstaBlaster
Great video Joe glad I have a dro! Got your name from RR in the shop glad he mentioned your videos.
Thanks Mike, I have to go over there and check that out. i am one of his subs.
Thanks Joe, I'll be watching this one many times. I actually a dial indicator but I don't have the test indicator type like your B & S. I also will be looking for the indicator holder like the one used in this video.
Excellent information, I to have a DRO and have grown lazy (smarter?) but it is always good to review the basics. I think this basic understanding will help you in all your setups with or with out DRO or dial indicator. Great video
Thanks Charles
Thank you sir for sharing all your great time and efforts to help us , god bless you and your family
Thank you very much for your extremely informative videos. You are a wealth of practical knowledge.
Been at this for a while. Thanks for watching.
Hi Joe, when I use edge finder on round stock, I make sure the edge finder is slightly below center, pick up the center, then post .100 on my "Y" reading on DRO, or if no dro, set my dial at .100, then measure the rod and divide by 2 and move that amount, no calculating or errors. Same with "X"!
yes, that is the way I was taught and there is no need for backlash calculations etc. This guy is a good dude but makes easy thing very complex
Thanks for these videos. I’ve been puzzling over this for a couple of days. Cheers friend.
Excellent video as usual. If I wanted to know how much backlash I had, I would probably just turn the crank one way to the zero, lock the table while still at zero, and then spin the crank the other way until it stops and read the number off the crank. I'm sure there is some finesse missing in this approach, but it seems like it ought to work.
The DRO was one of the best investments I ever made--the installation process is highly customized to your own machine and takes a month of Sundays but it's worth it. Always knowing the absolute position of the table is an amazing thing and we take it for granted.
Most machines more than a few years old, depending on how much use (or abuse) they have seen, can have markedly different backlash values at different positions on the leadscrew - almost always more in the center (where it gets the most use) than at the ends. My old Clausing has about 0.005 at each end and more than 0.020 in the middle. Over long distances that wear can affect the accuracy, too. This is precisely why I had to get a DRO for my machine and now never even bother to look at the dials any more.
I know - you're thinking it's time for a new leadscrew, but I've seen this phenomenon to some extent on every machine I have run in my 55 years as a machinist, except maybe a few new or almost new ones.
I learned, as you probably have too, that the indicator is your most valuable and precious tool. (Jo blocks are next in line for the title).
Thank you for this. Some of us are just learning in the home shop with an old fully manual drill mill. Mine is a Jet-16 bench top 8 speed. I’m not even sure how old it is, 1980’s or possibly older.
Glad to help
Yet another thought provoking video Joe, which I understood very well as I used to teach high school metalworking / engineering here in the UK and had to explain the theory of backlash to the students. this by the way was long before the advent of digital readouts, when digital meant doing it with your fingers! This was extremely well explained, once again thank you.
Thanks for watching and for all your comments.
Joe, I must apologize in the first one your videos I watch I said something to the effect of camera was a bit on the bouncy side I was wrong, sorry. I am interested to know what type of camera you do use though. I want do a video on gear cutting which is one of big things we do in our shop. This video was one best the explanations of backlash that I have ever seen, you took an issue that every serious machinist has to deal with on much a weekly basis if not more, got to the basics to application clear, concise and timely fashion. Another hit, keep 'em coming.
Cheers, Doug
I use a GoPro Hero 3 and a nikon b500. The Nikon is for the super close stuff and the go pro is for the general shots. You can tell which is which by the fisheye effect the GoPro has.
You CAN find true center with just the edge finder, no DRO, on a machine with unknown backlash.
You find the edges left to right then right to left. The difference is the backlash. Split that and you are on center.
This works on round and square stock.
Love your shirt! Oh, your videos are great too. I've learned so much from you. Keep 'em coming!
P97, P95 and a bunch of others. Represent ! Thanks for watching
I appreciated your responding to my comment.I would suggest that you might consider making a video on the best way to
machine a rectangular block. I have seen some videos on machining blocks
which are about 1" square. In the real world you need to machine parts of
bigger size.It amazes me that I have had people working for me who were in the business
for a number of years but did not know the simple operation of squaring a
block. They use a machinist square, a level etc.
In a job shop you try to develop good habits that produce consistent
results. You try to do things by the best method in the shortest amount of
time.You might find this of interest. I noticed that you are wearing a Ruger
shirt. My nephew was living in Chicago with a woman who has heavily
opposed to owning guns.My nephew divorced her moved to San Antonio and is engaged to marry a
Texas Gal. I told him that if he moved to Texas that he had to buy a gun,
get cowboy boots, and purchase a Stetson at Paris Hatters.In one year David presently owns 8 handguns, a pair of boots, but has yet
not purchased a hat. I am going to his wedding in San Antonio in April and
he has arranged that after the wedding we go to a firing range. Seems
appropriate.Again you make great videos and I would encourage anyone who is interested
in this trade to watch.Charles
Much appreciated Joe. Some things aren't obvious/intuitive until someone bothers to put them on a whiteboard and break them down.
The backlash depends on the measuring position of the table. In position where it is most used (Centre of table stroke) the backlash would be bigger than at the end. Very good film and great explanation od the problem!
Thanks Joe, your advice is just priceless.
Great vid Joe, your such a great teacher. Keep them coming.
thank you Daniel
Another great video Joe,, hope u realise what a fantastic help you are 2 all us newbies out here. Have watched ALL your videos.. well.... except for the bloody spider one EEK!! LOL keep them coming mate. Still don't get the one on using Trig angles on the compound. :) That's my fault though... not yours! I will go back and watch it another 2 or 20 times till I get it. You have got me addidcted... i spend more time watching your videos than I do out there on my machines... LOL
Thanks Warren. Thats a great comment. I'm glad I can help you guys out. Thats the whole idea here. Thank you for watching and commenting.
There are other ways to do this but it is your show.
Thanks for doing this as there is a ton of misinformation and poor practice on TH-cam,
As for backlash you can take up slack and re-zero the dials.
For sure. This video was posted as a courtesy to a very specific viewer inquiry. The theoretical and practical demonstrations are accurate and fairly broad in their scope. Not all machines have adjustable bronze nuts capable of reducing or eliminating backlash, so this level of information is very useful. I do appreciate the feedback and comment. Thanks for watching.
I would be very interested to hear your technique for calculating an accurate backlash value. Feel free to respond and share your thoughts when you get a minute.
Tried to post this and the comment is highlighted and cant post my reply.
Will try here.
I compare my feel for the dials with a dial indicator.
Is your businesses contact you email contact.
Worth
I will get the message if you send it there. Thanks.
Nice explanation Joe, thanks. I agree, a dial indicator is way more accurate than a traditional edgefinder. I've played around with lasers and ultrasonics, but nothing beats a dti, even a cheap Chinese one!
I treat mine like gold. Its my most important tool.
I concur with "get an indicator." My century old lathe has more wear in one area of the cross slide feed screw, as many (most?) of them do. If I happen to be working in that transition zone from 'more worn' to 'less worn' the reading according to the cross feed dial will go off. Frustrating to take the last .010 off of something and discover that, on that last pass, you actually took off .012, turning the snug fit you were going for into a floppy fit.
And it's nice to see that I'm not the only one that believes in using match marks.
They are the cheapest DRO's on the planet !
Hello Joe. Another great video, as usual. In regards to backlash, you mention in the video that it will be a constant we can measure on our own machine, and keep that number for reference. My question is, wouldn't the amount of backlash on an older machine be larger near the center of the lead screw, where the most wear has taken place, as opposed to the ends? Or do you think this difference should be negligible, provided the machine isn't completely worn out? What do you consider acceptable maximum for backlash on a manual knee mill, i.e. the point where the mill should be repaired, or replaced? Thanks.
I would expect older machines to be worn more in the center than the ends. 20-30 thou of backlash isn't necessarily a show stopper, but when you adjust it out correctly and the machine travel is restricted in some areas, it may be time to get it rebuilt.
Best and simplest schetch discription , Thank you!!
Excellent Joe, thank you for taking the time to do this.
Joe, you really earned this up vote. Excellent video. I have a question about edge finders. I've spent some time in a machine shop, used an edge finder quite a bit, and seen lots of guys use em, but I've never seen anyone use the other end (the pointed end). What is it for?
Thanks Joe. Good information. I do have a DRO but did the exercise to see what my backlash actually was. Also, I have an Indicol knock off and didn't know it had the dovetail tapers, took it out and sure enough, another way to hold the indicator. May use it more now. Doug Edwards
I use mine all the time. thanks for watching.
Great video... I could be wrong here, but if you have a DRO on your mill it shouldn't see the backlash because it only keeps track of the actual movement of the table. If you only have the micrometer collars then you will see it because they are attached directly to the lead screw of the table. I never notice the DRO reading change when I reverse the table until the backlash is gone. I guess you can check by just turning on the DRO and wiggling the handle back and forth and watch. Just a thought.
You are correct. A DRO erases all this worry. This video was shot in reply to a non DRO user wondering how to calculate backlash and compensate to find edges and centers.
Hi, I've only just found your channel... Great vids!
I'm more in to the welding side of things, although I do appreciate the good machinists channels too, well done.
Thanks. I do have great welding equipment here, but I don't have the polarized lenses for filming that kind of topic. I'm not talented enough to compete with the other guys on this topic either. Maybe someday.
This video is the answer to bolt circles, no digital readout. Having a 2d cad program to find dimensions from center. Been after this for a long time.
Shout out from El Paso, TX!! ONCE AGAIN, THANKS JOE!! \m/.
Happy belated birthday just got to your channel very useful info thank you keep them coming. Pollack in Willow Springs,IL
Thanks John.
Thanks Joe, really enjoying your very informative videos. Steve.
Thanks Steve
Excellent tip.
Does it matter what spin direction we operate the edge finder is?
Example assuming we start on x axis with x1 by the west end of stock, also we have no idea how far south (for instance) x1 is below the center line. Such condition, the probe can be more sensitive in one direction of rotation than the other. If unsure please run an experiment to rule this in/out. If proven that make difference we can always use up CW on x1 and CCW on x2 such that the probe always roll up hill against the stock. This can remove the uncertainty caused by x1 and x2 start indicating south of the center line. Please ask me questions to clarify my words.
Joe,
I really like the way you convey information.
I do have a question however about finding the edge of a piece of round stock. You covered backlash, but what about the behavior of the edge finder when you are off center, I suspect a new gremlin arises and that is the spindle rotation. I think the edge finder is going to behave differently depending on how the edge finder sees the round shaft depending on spindle rotation and if you are above or below the center line.
You assumed that the backlash is a constant. But that is not always true. Although the screws wear more slowly than a bronze nut, they still wear. And they wear unevenly because there is a zone on the screw which is used more often than others. In such a case your backlash depends on the position along the screw.
And you assumed that I assumed. Please read some of the comments below. thanks.
Thanks Joe. This has helped me get it clearer in my mind. And whatd’ya know? It works..
I'm no machinist, currently at school for engineering, and working on a bit of an interesting project on my own time. How would you find the center of a threaded hole? Trying to take a flange with 4 evenly spaced threaded holes and add a pattern of 5 threaded holes, and the best way is to have one hole in common between both patterns. And vice versa on a different flange. Current idea is to use the lathe and make a concentric locating pin to thread in the hole and use a method like this to find the center of it, while the whole flange is fixtured in a dividing head. Locate, turn, drill, thread, repeat.
2 ways. Use pins in the holes and locate on the minor diameter, or use magnification and locate off the countersunk edge of the hole. if its a quality hole, the c'sink was done before the threads and is a good reference to find center.
Thanks man....now I finally understand how this works with a edge finder! I do have a indicator, but I was just wondering. Now I know!
I'll use an indicator any day, but this was a requested topic. Its good to know.
Good info. How much backlash would you accept before you do something about it?
bold of you to assume I have a machine shop, let alone a garage at my -parents- house, maybe in the future, I'm mostly here for practical fun.
By the way, that LEGO Joe Pie has got to be one of the best things I've seen on TH-cam.
My daughter had that made. I like it too.
@@joepie221 bless her, nothing sweeter than a unique gift, no matter how small.
Hi Joe, thanks for all your excellent videos, I have learned a lot of new techniques.
I have a question with respect to centering a disk that is mount vertically with reference to the mill table. I want to center a hole on the circumference the goes from the OD to the ID of the part. The disk is too large to use an edge finder.
Any help would be appreciated, maybe you can create a video.
Thanks,
Dave
The backlash number will change on different places of the travel because we typically do lots more work in the center or where the vise is normally mounted than we do at the ends of the travel, so the lead screw tends to fit looser there because of increased wear in that portion of the lead screw. It's a moving target...
Its a good idea to move your vise L or R occasionally to spread this wear around. I alternate between the two I have mounted for just this reason. Thanks for the comment Bob.
Russ Hall
I have a very old and worn mill and it seems to me that I might expect to find the backlash different at different locations on the screw. Most of the ware should be on the nut which would be fairly consistent through all the travel, but the high use middle zone of the screw might have more ware on it than out near the ends. If this is true, it seems that I should check the backlash where I am working on the screw.
I'm thinking that you might move your table out to the ends of its travel in both directions. Then, get underneath with a flashlight and check out the acme threads. Measure every third or fourth thread with some accurate calipers to give you a rough idea of where you should be looking for different backlash.
You might find that the first inch or two the threads are like new. Then, they're about equal for another few inches, only thinner threads than at the ends. And, you find a big drop in acme thread thickness at some point.
If you bought your machine from a company's private shop, then all of the work was probably relegated to a section of the mills table. Or, you could get an inexpensive DRO, and not even bother with what backlash you have and where you have to be concerned with it, to one degree, or another.
I read in an old machinist tips & tricks book that you can find center of round stock with an edge finder by touching off x axis move in rad of part + rad of edge finder then y axis move in the same, repeat 3 more times.
Yes, I remember reading that in Guy Lautard's "Bedside Reader" book. It seemed a bit cumbersome to me.
@@ronmccabe1169 it's not ideal but when you don't have the ideal situation, overly gated casting, dial out for calibration, or I'm to fat & lazy walk over to the toolbox it's a good thing to know.
Hi Joe, don't know if it helps or not, but when I indicate a round part in the vise, I pick the x side first, pick the minus side, go until I hit zero, and zero my DRO, then pick up indicator and turn to other side and pick up zero, then split the difference on the reading, then the same with "Y" and it will be within a couple thousandths right away, then its easy to zero out!
This was a very specific video about not using a DRO, coaxial indicator or spindle mounted indicator. Those ways are super easy.
Good video Joe. Couldn't you have just rotated the dial indicator 90 degrees and use the side of the vise for the x axis?
I could have, but my base wouldn't reach.
Always tops. Nice to have you in Texas.
An edge-finder is not a good enough tool for round stock. Rounds have no edge that will contact an edge-finder squarely it has either got to kick out climbing up to the centre of the round or kick out running away from centre, never accurate enough. Dial indicator the easiest and more reliable than a DRO. very in depth vid Joe and well presented.
Thanks Steve. I'm not a big fan of the process, but I thought I'd approach it for a viewer. Indicator.....all the way !
Verybuseful for a non DRO man like me. Thank you again.
I use an indicator myself. This was done to address a specific viewer question. Good tip to know.
Great stuff and now when the Indcol shows up in the mail box,,,can show the wife why I must have one,,,hehe!
Great plan.
Cool, lego figure...I wouldn't mind if you adopted me joe...lol I hope she realizes how lucky she is to have a dad like u.....a lot of ppl don't....Thanx again for the video and info joe ...
And another great vid I was wondering what to do with the backlash problem < no DRO here brother Thank You
I actually have a video coming up on that very topic.
All your videos are excellent, but I walked away still a little confused at the end of this one! It was the last part where you were back at the white board just before the end. You made the comment that you were going to give your ending comments just a little more thought. I didn't understand your comment just before you said that!
How about a video on installation of a DRO?
I love the detail. I'm learning alot.
Thanks. Stay tuned.
Unrelated topic but I have a question you can probably answer. My shop is an old tin can that used to have a leaky roof. I replaced the leaky roof but here in mid Michigan we have an issue with high humidity and I'll find something I've sandblasted or something bare metal that I bought new pretty quickly develops a skin of rust. What to you use on your ways, what do you use on your collets, clamps etc? I just bought a new indicator, stand and a set of collets and I'm afraid to take them out to the shop! LOL WD, would last very long but might be a perfectly good product. I'm a mechanic and don't really use my mill and lathe all that often. The tarps come off those when I need to make something for the drag car or when someone shows up with an "impossible situation" they want me to solve. It doesn't pay very well but the bragging rights are awesome! So I solve em.
When I plan to be out of town for a while, I like to spray down my exposed machine surfaces with WD-40. It has always worked well. I also used to own a jet ski rental business in NJ and always prepared my machines for storage by spraying the engine and drive system with marine fogging spray. Those engines looked brand new every spring. You could probably use either and have good results.
thank you keep up the good work I learned something, that is why why i subscribed, new to this and want to learn . I love the lego, my family try to support me in my new expertise . i try to be jack of all trades but this is new. Look for many more tips.
Very instructional Joe, thank you
Jim
Thank you.
I have not pursued my thought but i often wonder if there is a variation in readings on round stock or internal bore readings when slightly off center due to rotational differences of the edge finder when approaching the part form opposite sides
I thought that as well. If it were a solid making contact, the tangent point would be a mirror image, so I would assume rotational influence would be minimal. Being as close to center as possible for the first leg at the time of contact by the edge finder would be highly suggested to minimize error.
Hi Joe. great gift from your daughter, thats serious cool lol. what id like to know: what to do when a dial indicator falls, is it totalled like you people call it in the states or can it be salvaged. using a edge finder to find edges and work my way to centre doing the maths
We really only use that term for vehicles. Your dial indicator is not typically repairable. It is scrapped, as we would say.
Is unloosen mean tighten.
Great video I learn a lot watching
I know it means to tighten, but its a word I've always used. I get some heat about that, but i'll continue to throw it in just for fun.
very informative Joe I liked this a lot but now I'm forced to ask,when indicating the part does that "slop" or "play" ever come into play on the "z" axis, z axis play I mean,thanks
Hi there, using a dial indicator to find the center, does just that, it only finds the center. All the play / backlash will still be there and if you need to offset a known amount from the center, you still have a problem knowing how much that is and in what direction i.e. cw or ccw. The only way to make real sure is to always take out the backlash in a known direction. When you have dialed up the center, set the indicator dial to zero, back away with the table handle and then come back to the zero from a known direction, and then set your handle dial to zero.. Sounds complicated, but when you have done it a couple of times, the procedure will soon sink in. As long as you always approach from the same direction, backlash is not a problem for setting dimensions, but it is a problem when machining. If you try to climb mill with a worn leadscrew, the cutter will crab and pull the work piece into it. Hope this helps.
Good points Dave. I try to always finish my position moves with a clockwise move on the dial. Either that or start at the back left of your part and work toward the front right. The table moves will always be clockwise moves on your dial.
Travis. I have to say yes to this question. Not so much for dimensional accuracy, but absolutely for machining rigidity under 2 special conditions. If you have ever tried to drill or plunge mill round stock on a round surface, you will notice a terrible bouncing between flutes leaving an awesome, but unwanted, chatter pattern on your part. By leaving some tension on your quill lock, or locking it completely and coming up with the table for the initial penetration, it goes away. Other than that, I really can't think of any other impact.
"Everything is awesome!" 😂🤣🤣🤣 👍 just for that! Basics video. Something that is important to know! Well done!
I wish the audio was louder on ALL of your great videos. Thanks!
I did not hear you mention that back lash varies with table position and screw to nut wear variations due to where you are doing your calculations
Wayne, your observations and comments are accurate. There are many conditions that may exist based on a hundred different variables. Naturally, if you intend to map out your machine, do it in your working envelope. I try to cover as much valuable material as I can while keeping the video to a comfortable watchable length.. How about shifting your vise off center for a year or two to work in a zone on your lead screw that may not be worn. Just a thought.
if you're not on center though ........with a kickout-centerfinder, one side it'd kick downhill. And one side it would kick up-hill. Wouldn't that influence the sameness of each point? At least if you start on center you always be kicking downhill. In other words the kick out would roll off the round part rather than climb up it. Anything to that? You could I guess turn your machine in reverse for the opposite reading. In fact that's the solution isn't it (if there is a problem)
That is very interesting. I would like to see how much effect that would have. Joe?
Not exactly sure what you're asking. Regardless of where "off center" you are on a circle (assuming you're looking down on a "circle" vs a rectangle, or some other oblique shape), the finder will always hit the part tangentially from both side.
The idea of using an edge finder totally eliminates any discussion of uphill vs downhill, because those terms are reserved for non linear flutes and approach directions to work. In addition, tools climb work because they're locked into a collet, or an arbor of some sort. The edge finder is designed to eliminate that, because it designed to kick out at the slightest touch. Again, uphill vs downhill doesn't even become a factor. It's all negated.
Assuming your round stock is lying flat in a vise, or v-block (instead of on its end, as in video) means the edge finder will contact the round bar where it is sticking out farthest AND will contact the edge finder on its corner edge (The ONLY place where this won't happen is when measuring the exact center of the round bar.). However, even in THIS case, there is no twist to worry about, because there aren't any twisted flutes. And, as also mentioned above, the edge finder is designed to "give" at the slightest touch. So, again, uphill, downhill, conventional, climbing, etcetera are terms that wouldn't be used here.
Therefore, NO, there is no influence being imparted by approaching the work from either direction by the edge finder.
I like that, finding the center. Thanks for sharing
Hey joe I know what you just showed on the backlash is to be true but if you know your machine you should feel the backlash and reset your dial when changing directions for most jobs
To find the center If you put a small rule on top of a round material using a small rule bring down a quail with a drill bit till the rule is level
If you put a pointed scribe in the chuck then on the rule is the scribe method more accurate (smaller the point more accurate) ?
It does seem logical.
Novices should realize the backlash slop will be different depending on what part of the lead screw is used. The center is usually worn more than the ends- use a dial indicator.
Love your vids, Joe. Gave you a shout out in the last vid, I hope it helps.
Thank you very much. I do appreciate it.
Brilliant explanation!