Z axis lost steps during machining process.

**jaru-eri** · 11-07-2020, 10:53 AM

Recently I experienced that my Taig mill took a very deep cut and ruined my project, so I believe it must hav lost steps during the machining process. Are there anybody here who have had the same issue and know what the problem is? My thought is that it lost the steps when it lifted up, so maybe the settings or the plung rate is wrong? The plung rate was 30 inch/min.

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**awerby** · 11-07-2020, 02:17 PM

30 ipm is a pretty aggressive plunge rate for anything harder than foam. What material were you trying to cut? Usually it's best to ramp into the material at an angle, rather than plunge straight down, unless you're drilling, not milling.

But if your tool is going too deep, I think you're right, and that you lost steps on the up-stroke, not the plunge. If the latter were true, your DROs would have registered a position at the bottom of the stroke that's lower than it really was, and retreated higher than it should have from there. Have you lubricated your Z-axis slides and screws recently? Is there perhaps some material accumulated in the works? Or are the gibs out of adjustment? Could the tool have pulled out of the collet that much? If this is a new mill and it's never worked before, I'd suggest lowering the acceleration rate. But if it's been working well up to this point, I'd look for a mechanical problem.

**jaru-eri** · 11-07-2020, 03:17 PM

Originally Posted by awerby

30 ipm is a pretty aggressive plunge rate for anything harder than foam. What material were you trying to cut? Usually it's best to ramp into the material at an angle, rather than plunge straight down, unless you're drilling, not milling.

But if your tool is going too deep, I think you're right, and that you lost steps on the up-stroke, not the plunge. If the latter were true, your DROs would have registered a position at the bottom of the stroke that's lower than it really was, and retreated higher than it should have from there. Have you lubricated your Z-axis slides and screws recently? Is there perhaps some material accumulated in the works? Or are the gibs out of adjustment? Could the tool have pulled out of the collet that much? If this is a new mill and it's never worked before, I'd suggest lowering the acceleration rate. But if it's been working well up to this point, I'd look for a mechanical problem.

It´s an old mill and I was cutting a 3d surface in arvorin which is a faux ivory resin. This get a lot of small chips which maybe got attached to the z-axis lead screw and caused problem that way. The acceleration was set to 9mm/sec.

**sclelectronics** · 11-09-2020, 12:18 PM

Being that aggressive on the z axis..
Check the lube and smooth functioning of the leadscrew and headstock sled!

Stuart

**jaru-eri** · 11-09-2020, 08:35 PM

Originally Posted by sclelectronics

Being that aggressive on the z axis..
Check the lube and smooth functioning of the leadscrew and headstock sled!

Stuart

What will be the correct settings, and how do I check the smooth function? I have reduced the acceleration to about 7mm/sec. Do you think that is OK or do I need to reduce it more?