Hi guys, I’m new here and am setting up my new used taig cnc. I have it working and have done a basic setup. I have trammed the column and spindle dovetail separately to within 0.001” and tightened all the gibs and backlash screws. Unfortunately, I am still 0.010” off in the X axis when making parts. I haven’t checked the Y axis yet. What’s weird to me is that when I put a dial indicator on the machine to check its movement, I was only off by 0.001”-0.002” over 0.060” movement. This appeared to be backlash, since it was off the same whether I moved 0.075” or 0.005”. I updated mach3’s backlash settings, but my parts are still 0.010” too large on the X axis. Any suggestions on what to check or tune? I’m currently tightening all my gibs and backlash screws again. I tried adding a couple 0.005” finishing passes on the parts that are measuring large. I’m getting the same results. Thank you for reading!
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Help with Taig CNC mill setup please!
- Thread starter jimmy2trucks
- Start date
Thank you for your reply. I just checked my cutter. It measures 0.125” like it is supposed to.double check the actual cutter diameter and the setting in the machine?
Can you confirm the lead of the ball screws and compare to the motor configuration settings. I would assume that both the x and y axis ball screws are the same so you could compare the settings. Steps per inch or mm. How long is the piece you are machining. The bigger the piece, the more accumulative error. Flip the piece and cut the long dimension using the y axis to confirm it’s not doing the same thing.
Another check: use a dial caliper and a pin in the spindle vs something on the bed. Do a chart over the range of the caliper, then reverse direction and keep recording.
Sent from my SM-S911U using Tapatalk
Sent from my SM-S911U using Tapatalk
The settings match for both. The machine works in inches—its set at 40000 steps per inch. Over half an inch of travel, it is right on measuring with a dial indicator. The part I’m making is half an inch wide. I’m starting to think maybe my lead screws are worn, causing more backlash in some areas.Can you confirm the lead of the ball screws and compare to the motor configuration settings. I would assume that both the x and y axis ball screws are the same so you could compare the settings. Steps per inch or mm. How long is the piece you are machining. The bigger the piece, the more accumulative error. Flip the piece and cut the long dimension using the y axis to confirm it’s not doing the same thing.
I’m very intrigued by this but am not exactly understanding.Another check: use a dial caliper and a pin in the spindle vs something on the bed. Do a chart over the range of the caliper, then reverse direction and keep recording.
Sent from my SM-S911U using Tapatalk
Basically, set up two things you can measure with a caliper. One fixed, one moving with the spindle. Move 1", 2", 3", etc. Measuring at each step. Then go back to the start, measuring at each step. You are looking for 1" requested =1" moved, and the numbers matching going both directions. Ie, the 1" going left =1" going right.
A long overall measurent helps sort small leadscrew vs steps per inch issues.
Matching looks for backlash.
Sent from my SM-S911U using Tapatalk
A long overall measurent helps sort small leadscrew vs steps per inch issues.
Matching looks for backlash.
Sent from my SM-S911U using Tapatalk
I understand! Thank you for the idea. I’ll do it.Basically, set up two things you can measure with a caliper. One fixed, one moving with the spindle. Move 1", 2", 3", etc. Measuring at each step. Then go back to the start, measuring at each step. You are looking for 1" requested =1" moved, and the numbers matching going both directions. Ie, the 1" going left =1" going right.
A long overall measurent helps sort small leadscrew vs steps per inch issues.
Matching looks for backlash.
Sent from my SM-S911U using Tapatalk
I am also looking at my nc program wondering if maybe I’m getting some tool flex. I set it to cut a 0.005” finishing pass at the end, but maybe two would be better? I know that the tool is mounted square because I trammed the column to within 0.0005” and did the spindle dovetail within 0.001”. I would not expect any flex on such a small finishing cut though.
I will post results of my measurements once I take them
I tried what you said @Weldingrod1. I got consistent results on the right side of my vise—only an extra 0.0005-0.001” per inch moved. The left side was a bit harder to measure accurately just because i had the stationary side of the caliper on the tool instead of on the vise. But over 3” I saw 0.002” total deviation (after repeating the test a few times). That’s good enough for me right now—I’ll adjust steps per unit once I figure out this 0.010” deviation. I’m thinking I might make another part and add maybe 3x 0.005” finishing passes with a fresh endmill to see if maybe I just made a bad nc program. I think I’ll try a larger mill also (1/4” instead of 1/8”). But I’m open to more ideas!