Cutter and Backlash Compensation on the Milling Machine

[@daveticehurst4191]

Hello Tom, you made hard work of all this backlash. Providing that you always work in the same direction for the backlash, you can just use the dials, no trial cuts needed and no marker pen. You had edge found anti clockwise and set the dial, you had also milled the back edge anti clockwise .375 thou. When it came to doing the front edge, all you needed to do was with the tool retracted from the milled pocket; move the table .400 thou + clockwise past the centre, then wind the table back anti clockwise until the dial reads .375 thou. Run the cutter and plunge back to your original depth. Do the same in the X direction, job done. You then have no need to know how much the backlash is in each leadscrew. Hope this helps others. Obviously it still works in the other direction if you have edge found in the clockwise direction, then always work the dials in the same direction. Another of your interesting machining tips, well done.

[@artgoat]

+Dave Ticehurst That might work in this one, specific example, but Tom gave a good tutorial for general use. For example, recently I needed to bore some tubing to a larger size (no, I couldn't chuck it in the lathe, because it was welded into 3/8" plate that was longer than the swing of my lathe). The best way to find the center is to touch off four sides of the circle with an edge finder. How do you know what the center is if you don't know how much the second touch is in error? So while this may have been overkill for this exact job, that wasn't the point. As a general-purpose tutorial on backlash compensation, it was exactly what I needed.

[@rcytb]

Excellent; thank you. It's been 50 years since I last ran a mill in high school, and this was a good refresher. Also, greetings from the lower peninsula!

[@TomsTechniques]

Thanks for watching. I'm from the lower AND the upper peninsula depending on the season and my state of mind. :) Tom

[@pierresgarage2687]

Hi Tom, I appreciate your involvement with all of us. DRO's are so much of a blessing, until recently I was using my lathe without one, I did get used to it, like a second nature. I find that operating a milling is more awkward without a DRO than the lathe was. That makes me appreciate that both my machines now have DRO's. VIVA Dineros, VIVA DRO's Thanks again, Pierre

[@TomsTechniques]

Thanks Pierre. I don't have a DRO on my lathe, although I will probably get one in the near future. They are much more useful on the mill, but all that usefulness does come at a price. Thanks for watching. Tom

[@lockbuilder]

Tom I can't tell you how useful that video was. I have been doing all that by trial and error. I can't wait to try this tomorrow. Thank you!

[@TomsTechniques]

Once you get comfortable with backlash, machining will be more fun and the quality of your work will improve. Tom

[@rlawrence78]

I am very happy I found your channel. I am saving for my first mill and have been interested in learning as much as I can. Thank you very much for taking the time and posting.

[@TomsTechniques]

No problem, I hope you enjoy the videos. Tom

[@rljzathras]

I have the DRO on my mill, but you really can't beat the nice analog feedback you get from reading dials. Sometimes the rolling digits are less of a help, but that nice linear scale is.

[@TomsTechniques]

It is easier to overshoot with a DRO although I doubt it'll make me switch back to dials. An analog bar like you see on digital multi-meters would be nice on a DRO. Tom

[@rljzathras]

Toms Techniques I agree that I still use the DRO, but with the modern proliferation of cheap graphical displays perhaps one day we'll see a DRO that as well as the numbers, shows a simulated hand wheel with virtual sharpie marks for end points (no backlash compensation required!). The graphics display hardware is cheap these days with the likes of Raspberry Pi's etc, suitable LCD displays likewise. Perhaps if I get bored one day!

[@volcom7114]

Another great video Tom! I enjoyed this one. DRO's aren't cheap and a lot of hobbiest can't afford one right off the bat so this will be a big help to us all thanks! Dennis

[@TomsTechniques]

Thanks Dennis

[@outsidescrewball]

Hi Tom Great lesson and this video makes me count my blessings that I bought a DRO for my mill.....I had forgot everything you just showed when using dials, also have trava-dials on both x&y on my lathe. Chuck

[@CompEdgeX2013]

I put off the DRO for the new mill until I get it moved to it's new location. So for now still using dials...I'm glad they are decently well marked and have little backlash. Great video Tom. It's easy to get confused for sure but a little logical thinking clears it up a bit. Colin

[@TomsTechniques]

Thanks Colin.

[@FredMiller]

I am going to have to watch this one a couple of times Tom.. As a beginner I am still having to double check myself to make sure that I turn the dials in the right direction to do what I want to do... Especially when I am in a corner and don't have any wiggle room. Nice job... Thanks

[@TomsTechniques]

Don't watch it Fred, do it for yourself. Practice is the best way to get the feel for what the machine is doing. Just remember that the end mill is stationary and the part is moving. Tom

[@FredMiller]

Your last sentence that the table moves not the end mill was an Ah-Haa moment for me a couple of months ago. I also look at the dials and think of the table as a big X-Y graph and that returning to 0,0 always is lowering the numbering on the dials (works for me) and eliminates the confusion factor. Thanks for all your tutorials they help a lot of us....

[@jhareng]

Toms Techniques Another great video Tom. Never a truer word about 'feel' often lost outside a working environment and CNC programming. Doing stuff like the vid shows up the weaknesses in any machine which may not be just the lead screws.

[@cotesgarage3391]

hi after watching this I used the dials to do a 5 bolt circle with x and y as I don't have a rotary table, I was surprised how well it worked once u get ur head into it, also want to comment that I have used a few of you're tips and have been very helpful, one was cutting a 1 1/2 - 8 thread ,,turned out nice, thanx for the tips Terry

[@TomsTechniques]

Thanks Terry, glad you got some use out of the videos. Tom

[@rcwarship]

Tom, thank you so very much for taking the time to make, edit & upload this video. Fantastic job of explaining/carrying out this operation. NICE! Best Regards, Jon

[@TomsTechniques]

Thanks Jon, glad you enjoyed it. Tom

[@NoTimeForThatNow]

Strongest argument for DRO I've ever seen. :)

[@TomsTechniques]

This one was painful to make because it has been so long since I've had to think about backlash. Digital readout is definitely a worthwhile option if you can afford it. Tom

[@AmateurRedneckWorkshop]

Great video. I watch them all and learn tons each time. Thanks.

[@TomsTechniques]

Thanks for watching.

[@shawnlund]

Thanks again Tom,the dials on my 8520 are great and I actually enjoy using them. Wasn't sure how to compensate for backlash like this though, great stuff and well presented as usual.

[@TomsTechniques]

Thanks Shawn.

[@tombellus8986]

That was a great video it brought back a lot of memories. really enjoy your work, very professional and easy to understand. Thanks

[@TomsTechniques]

Thanks Tom.

[@jasincolegrove6651]

This is the type of video that is most useful for us layman's. Good measuring skills required.

[@artgoat]

Thanks a great deal for this. This is a tremendous help. I was needing this for reaming a hole to a larger size with a boring fixture. My cuts kept ending off about ten off-center. Now that I understand what's going on, I think I could find the screw backlash by using an edge finder and a block of known size. I made the mistake of thinking that the backlash could be felt. Obviously not, since in the video what looked like .010 backlash turned out to be .037!

[@TomsTechniques]

+artgoat You don't need (or want) to know how much backlash a screw has. You just have to know how to deal with it. The problem, especially on older machines is the backlash varies over the length of the screw due to wear. Just compensate for it as I demonstrate in the video and you'll be fine. Tom

[@artgoat]

+Toms Techniques Yeah, I figured the lash would vary by position. The technique would be a little different for centering a hole, I would think, especially if there is a question whether the hole is perfectly round (part of why I'm boring it). So it has to be in the perfect spot before the tool goes down. Can't bore it first then see how far off I am. I know how to touch off the sides of a circle to find the center, but the center needs to be displaced by 1/2 the lash on both axes. I don't understand how to do that without knowing what that is.

[@TomsTechniques]

+artgoat Holes are easy. All you do is pick up the edges of the part with an edge finder and move in the required distance to the center of the hole. As long as you turn the crank the same direction as when you picked up the edge, the backlash will be irrelevant. Tom

[@artgoat]

+Toms Techniques Well, it's obvious I'm failing to convey the issue, but I've taken enough time on an old video aņd I can probably figure out the rest. Thanks again for the video.

[@ArrowXDesign]

Good job explaining something that's irritating to monkey with in the first place. This sure makes me want dro scales more now. Another thing is trying to remember which way to turn the dials. I ended up writing CW & CC with arrows right on my mill table after screwing up hours worth of work toward the end.

[@TomsTechniques]

Just remember that the tool is stationary and the part moves, then you won't crank the wrong way. Thanks for watching. Tom

[@whitecaps775]

Thanks Tom, New to this stuff, glad you are there.

[@TomsTechniques]

Great. I hope you enjoy the videos. Don't forget to check out my website tomstechniques.com. Tom

[@Tryin2FlyII]

Outstanding Job! Great Camera work, Great Explanation!!! and Machining -All with one hand!! I don't know how I missed this video? Glad I found it though- I think you said its been 40 yrs since you used dials you still did that pretty fast!That would have taken me 1/2 a day to try and figure out how to do that and get it right on my own lol Thanks for this and All your videos!

[@TomsTechniques]

I actually used two hands, with the third one on the camera. DRO's make using dials obsolete, but you never forget how to use them. It's just a pain in the ass to do so once you've been spoiled. :) Thanks for watching. Tom

[@TheChitownMachinist]

Glad to see your Yooper Pride!! Ps...Love your videos. Im sure they are helping out apprentices and hobbiest everywhere! Keep up the great work!

[@TomsTechniques]

Thanks Eddie.

[@EZ_shop]

Wow, that was stressful to watch! Good job Tom. I hope my DROs never die.

[@TomsTechniques]

It was supposed to ease stress, not create it! ;) Thanks

[@michaelrogers8682]

Hey Tom Great videos, I've learned a lot. Keep the awesome videos coming.

[@TomsTechniques]

Thanks for watching!

[@turnmaster1754]

tom i can tell you why your cut size was off in one direction if you watch vary closely just after 15:35 u will see u turn the X axis a bit fast and your dial stuck a bit in your turn u will see it if u watch vary close. thanks and keep up the good work

[@TomsTechniques]

"Off" is a relative thing. If the tolerance on that slot was plus or minus .005", it was right on. A mistake many machinists make is to spend too much time machining to a theoretically perfect dimension when getting it within the specified tolerance is just as good and takes much less time. Besides, if I wanted the slot any more precise than it was, I wouldn't have been using calipers. Thanks for watching! Tom

[@pthomps1954]

I was hoping you would measure how far the pocket is from the edge. Good video. I showed someone how to do the same thing on his mini mill and I think it turned him off from doing any machining. Also, have you ever heard that you get better accuracy if you don't let the cutter cut on the bottom and sides at the same time? It seems like I do better if I lift the cutter .001 before taking the finish cut on the walls. I have a mill/drill which might allow the endmill to run around if it touches the bottom.

[@TomsTechniques]

Checking the edge distances is certainly something that can be done to ensure location. I was more interested in showing how to deal with backlash in this video. The fact that you get a better finish with the cutter off the bottom is a rigidity thing. It's not an issue on a heavier mill. Thanks for watching. Tom

[@coyzee1]

Thanks Tom, I'm so glad I have a DRO on my mill, I could imagine my stuff ups without it. I suppose backlash on the lathe is not often a problem as we're mostly cutting in one direction?

[@TomsTechniques]

Backlash on the lathe needs to be compensated for as well. How about grooves in the end of a part? Or parts with turned OD's and ID's? Thanks for watching. Tom

[@Freak0NatureX]

one trick i learned from a friend, is use an edgefinder to zero to the upper right corner of the vice,with backlash in proper direction, then u can line up parts with the right edge of vice, and it will be aligned at 0,0

[@robisilas]

Hi Tom, would it not be easier just keep on going all around? I only have a toy drill/mill from Harbourfreight, I use in X-Y direction a couple of 2" travel dial indicator and keep going around. To feel where the back-lash begins and ends is very difficult otherwise. Rotating the dial back and front again, probably it's ok on your nice mill, unfortunately I am never sure of that, due to different friction between screw and nut at different points of the spindle which is not worn out evenly. Nevertheless you showed a few interesting things.Thanks. The Old Bob

[@TomsTechniques]

Hi Bob, This video shows how to compensate for backlash when not using a direct readout like a DRO or indicators, so you need to establish the edges of the pocket before going "all around". Having never used a Harbor Freight mill, I'm not sure what you mean by variable friction, but the bottom line is you have to know your machine and how to compensate for any issues it may have. Thanks for watching. Tom

[@cliffjones1511]

one more Great video, I am also thankful for my DRO Please keep up the great work

[@wiav8r]

Great video Tom. Ya had me confused for a bit but I figured it out. Time to turn the DRO back eh?

[@TomsTechniques]

The concept is confusing, which is why so many have trouble with dials. Backlash is a concept that needs to be mastered though if a DRO is out of reach. The Sharpie really helps keep you track of where you are. Tom

[@rchopp]

Thanks for the lesson Tom, good stuff as always.

[@TomsTechniques]

Thanks.

[@cotesgarage3391]

hi I tend to use dial indicators..just gotta make sure they don't get bumped :(,,

[@gohuskies583]

Nice lesson Tom! Like the shirt too. Say ya to da UP, ey? I spent 5 years up there at MTU....

[@TomsTechniques]

Thanks. Ya, we love up there don't ya know?

[@gohuskies583]

Ah, you betcha!

[@Vickwick58]

If you had to square up those corners, what would you do?

[@TomsTechniques]

Victor, One way is to use the quill of the mill as a slotter and plunge a stationary tool into the radius to cut it out. If you check out my video on building the Stevens, there are some pics showing the process. There is also more detailed information in the build thread. You can find that in the gunsmithing section of metalworkingfum.com. Another option is to make the corners functionally square by taking a plunge cut with the end mill while centered on each corner of the pocket. It's not as pretty, but works just as well. Tom

[@Ed_Row_Feez]

Is it advised to take a measurement and measure the screw’s backlash for every cut. Or can you assume it is the same amount for each leadscrew once you find it. In other words, can it vary throughout a lead screws total length or is it always consistent

[@TomsTechniques]

I think before adopting that procedure, I would check the backlash of the screw at various points to find out.

[@finnrock5558]

I'm a little late to the party but I have a question: Is the backlash the same at all positions along the screw? By that I mean, if I measure 18 thou with the table all the way towards me, will I also get 18 thou with the table away from me? Also, other than thermal expansion of the screws and stuff, will the backlash be the same every time or should I remeasure every day/part/op I would try all this for myself but I don't have a mill or lathe (yet)... Thanks to whoever wants to help.

[@TomsTechniques]

The backlash will vary along the screw on older machines because of wear on the screw. On most mills about 90% of the work is done on the center foot or so of the table. It's best to just compensate for the backlash in every setup, rather than try to predict what it will be.

[@finnrock5558]

@@TomsTechniques thank you very much for your video and your reply

[@2111onyx]

Tom great video as always...was wondering what the fixture is for on the back of your vise??

[@TomsTechniques]

Thanks. The bar on the back is the mount for a work stop. There is an arm with a set screw that can be attached and the work located off of it for multiple parts. Tom

[@Prowler901]

Thanks for your efforts on all these videos, Tom. I'll be using your method here to determine the backlash on my mill. The backlash should be consistent throughout the length of the screw, right?

[@TomsTechniques]

I never assume anything in machining. If your mill is well used, the backlash may vary along the length of the screw and it will certainly vary from screw to screw or machine to machine. I would recommend always using this method, or something similar whenever you use dials. Once you get the hang of it, compensating for backlash will be second nature.

[@Prowler901]

Toms Techniques Right. Didn't think about how there could be more wear in the areas that are used more. Probably close to the center of the table I'd imagine. Thanks.

[@Rover109able]

Very informative,thank you

[@TomsTechniques]

Thanks for watching.

[@jimmilne19]

Super for me. I have a Vilh. Pedersen knee mill and no DRO. It is really a hassle to deal with dialing everything in. I assume that backlash is not an issue with DRO because one is working with the actual position of the table. Do you have a suggestion for a DRO? I've been looking, but not finding. Thanks for the informative guided tour.

[@TomsTechniques]

These guys have glass scale DRO's for around $500: www.dropros.com/DRO_PROS_Milling_Machine_Digital_Readouts.htm

[@jimmilne19]

Toms Techniques looking at the link now. Thanks.

[@everettnewtonable]

Jim, if you don't mind a little DIY, you can get into a DRO for much less than $500. It's not for everyone I understand, but good enough for someone who doesn't mind a little project to save a few bucks. www.shumatech.com/

[@jimmilne19]

Everett Newton Super initiative from shumatech, and helpful site. However, I don't have the skills nor the time to build one. I thank you for taking the time to help me out. Much appreciated. I'll probably have to buy.

[@TomsTechniques]

Everett Newton Hmmm. The link was dead when I tried it.

[@andregross7420]

What brand mill is that? Really nice dials, my '48 BP (before satin chrome) has plain steel dials and no flats for the stationary line just on the round portion of the bearing bracket, and are sometimes hard to read.

[@TomsTechniques]

It's a DoAll 200V with a 9" X 49" table and variable speed spindle. I bought it new in the mid 80's when BP was having quality issues after the Textron buyout and it has served me very well over the years. Tom

[@thoperSought]

the camera was fine, Tom. a little bouncy, but by doing it handheld, we got to see all the important things very clearly.

[@TomsTechniques]

That's good to hear because bouncy close-ups can be painful. Tom

[@thoperSought]

Toms Techniques I know what you mean. anyway, this worked out very well.

[@219garry]

Having ball screws vs the worm gear takes backlash from about .020 to .002

[@TomsTechniques]

They are a nice upgrade if you happen to have a couple of grand laying around that you aren't using.

[@wiav8r]

Yooper? Are you in the UP Tom? I was a short time resident in Gwinn MI (80-89). Yah eh?

[@TomsTechniques]

We have a place on Lake Michigan near Naubinway, but I think it's still buried in snow. Last time we were up there was four feet on the ground don't ya know? Tom

[@wiav8r]

I spent 9 years at K.I. Sawyer AFB MI. Now live in Central Wisconsin. Yep I know all about the deep snow. I even used to own a "Yooper Scooper"

[@karlmansson8319]

But your backlash will not be present in the direction in which you used the edge finder, right? So so long as you cut in the direction in which you fed the edge finder your dials will be accurate. And as long as you reverse your screw and move it forward again you will get an exact measurement. Won't you?

[@TomsTechniques]

Backlash has to be compensated for whenever you reverse the direction of feed. If you pick up an edge, all moves in that direction will be valid, but as soon as you feed the opposite direction, like in a pocket, you need to compensate for backlash. Tom

[@karlmansson8319]

Thanks for replying! Yeah, it took me a little while to wrap my head around it but now I understand. For arguments sake: if you were to feed in from the edge and then plunge at your target dimension instead of feeding in the opposite direction, you'd end up at you finished dimension, would you not?

[@TomsTechniques]

Yes, but don't forget to compensate for the cutter diameter if you are milling. Tom

[@cpcoark]

I like your hooper tee shirt. you from the UP? Sorry but I'm a troll and proud of it.. Also I just want to say I love the HP calculator you use. I doubt there are to many left that know how to us RPN.

[@TomsTechniques]

We have a cottage on Lake Michigan just outside of Naubinway. Going up next weekend to see how much snow is left. Last time there was four feet on the ground. I an unable to use an algebraic calculator. RPN is just so logical. Not sure why it never caught on. Tom

[@RMancilla10]

Shouldn’t you have taken .009 off of both sides to ensure the pocket is center? Since you were .005 short on the backside? So in theory you’d be .005 off center

[@TomsTechniques]

I had to go back and look at this 10 year old video to see what I was doing, and the answer to your question is no. All off the backlash compensation cones off one side. Remember that the backlash compensation is only applied in one direction, not both, so it doesn't have anything to do with the centering of the pocket.

[@RMancilla10]

@@TomsTechniques thank you!

[@helmsplitter0233]

when you say back lash you mean play in the handle right?

[@TomsTechniques]

Backlash is the clearance between a screw and nut and must be compensated for when machining. Every lead screw has it, unless it is a ball type lead screw. Tom

[@helmsplitter0233]

Toms Techniques clearance between the threads of the screw and the bolt?

[@TomsTechniques]

helmsplitter0233 Yes. All screws and nuts require clearance and this produces backlash. In other words, when you move the table on a machine one direction and then try to move it the other direction, that clearance must be taken up before the table will move. That's backlash. Tom

[@helmsplitter0233]

Toms Techniques ah thanks

[@Opinionator52]

Hi Tom, no readout does keep you on your toes, but it kinda like riding a bike... :o] O

[@TomsTechniques]

Yeah, I've spent a lot more time without a DRO than with one. It never really goes away. Tom

[@zxcvbnm6669]

Awesome

[@Freak0NatureX]

the dial struggle is so real

[@TomsTechniques]

I'm definitely spoiled with the DRO. As I pointed out in the video, this was literally the first time I've messed with dials in many years. Spent a lot of time using them though before the advent of the digital readout. Tom

[@ceesweerheim990]

I suggest that all you guys that do not have a digital readout that you save up some money real quick!

[@TomsTechniques]

DRO's are a luxury, but definitely not a necessity. I had been a machinist for ten or fifteen years before I used my first DRO. Yes they are a time saver, but you can get by just fine without one. Tom

[@ceesweerheim990]

Hi Tom Possible yes, but if had to use dials only I would be in for a lot of mistakes. I got lucky with mine, I repaired about 10 readout units for a local company and my payment was in the the form of a secondhand readout. Subsequently my home got hit by lightning and blew the unit to pieces. Luckily insurance replaced the unit with a brand new one! Enjoying your videos thanks!

[@guycomyn708]

Hi Cees hows the woodworking going

[@ASEANMACHINE]

คัตเตอร์มิลลิ่ง

[@ASEANMACHINE]

Milling cutter

[@sparkyy0007]

2 words.... ball screws.

[@TomsTechniques]

One word...expensive. ;)

[@sparkyy0007]

@@TomsTechniques I've got a Toss mill and do this edge finder setup all the time... with a 10 foot length of 1 inch ball screw on my rack I bought 8 years ago with nuts for $1000. It's true, the mechanics car is always the last to get fixed lol. Maybe this weekend...

[@johnohara54]

Your topic was "backlash compensation" and it was clear as mud. I understand what backlash is and how there is a need to compensate for it buy our explanation of HOW you did it was no explanation at all." I'm going to 165 ; no wait 175 ....." Why are you going there? Explain, explain, explain. I had difficulty determining what was your "X" and "y" axis and WHAT were you moving; the work or the end mill. Confusion'!!!!

[@karlmansson8319]

He did explain it. He measures the amount of backlash in the individual screws by measuring how much of the cut is missing in the part. He then adds that value to the cut he needs to make in that direction to end up att the true position. As the handwheels were set to zero by feeding the table in the opposite direction, that direction will be precise.