Hi All,
I’m experiencing some Z-axis movement when cutting very dense woods like Purple Heart. When I check my Z-Zero after the part is complete, the bit is about 2mm above my original setting.
I feel like my feeds and speeds are pretty safe, (40IPS at .06 depth per pass). But let me know if that’s too fast or deep.
Any help would be appreciated. Thanks.
Check the machine mechanically — belt tension, pulley set screws, eccentric nuts.
It might help to remove one spring temporarily.
If possible, ramping in will help.
It would help to have an idea of the dimensions — you lose 2mm cutting how deep?
I checked all the V-wheels and belts for the Z-axis and couldn’t find any obvious problems.
I was already ramping in at 2deg for this specific part.
The operation was intended to cut through 21mm, but stopped after about 19mm. That’s when I checked the Z-Zero and noticed the difference of about 2mm.
Check for loose or incorrectly positioned setscrews on the Z motor pulley (they must be tight, and one of the two must be positioned against the motor shaft’s flat). Even if they do seem tight, do the marker test to be really really sure the pulley is not slipping on the shaft:
With a marker, draw a line across the pulley and shaft,
Rerun the job, and if the Z zero drifting issue is there, check whether the pulley and shaft are still aligned. If not…setscrew problem.
Also check whether the endmill is slipping in the collet (measure the stickout before and after the run)
EDIT: also, are you using a Sweepy by any chance?
Thanks, I’ll try this next.
I use the Suckit Dust Boot
I’d also suggest showing down the plunge, it can be set sep., and 40ips sounds a bit high for hardwood plunges.
Sounds silly, but ensure that you’re tightening the collet sufficiently. I had an issue with an inaccurate bit setting workflow due to the bit slipping when setting z offset.
I created the mark this morning, so we’ll see what happens after I run a few tests. I did notice that the flat spot on the shaft was nicely aligned with the setscrew…
This is a problem i’ve noticed before with Purple Heart. Maybe I just need to slow down when cutting such a dense material.
Possible. You might be losing motor steps.
While you’re at it, make a mark on the endmill shaft too, to see if it slips in the collet.
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