Hi all - am having a problem when doing longer 3d carves.
After a roughing pass the finishing pass seems to start ok, I have the machining allowance set to 1mm in vectric so there is a nice obvious ‘line’ as the finishing pass progresses.
As the job goes on - say after a coupld of hours, the ‘line’ is less obvious which would suggest that the bit is riding slightly higher than when it started and towars the end of the job the line is almost invisible and machining marks from the roughing pass remain visible after the finishing pass.
At the end of the job I checked the Z height against the spoilboard and I needed to lower it nearly a full milimetre after the Z zero showed on the masso.
I can think of only 2 possible conclusions:
The bit is slipping in the collect - dont think this is the issue as I always clean the collet and tighten it up fully.
The Z axis is somehow losing steps, which I thought was not possible with the masso steppers.
It cant be anything to do with the level of the wasteboard as even if it was not level the roughing pass would absorb this tolerance.
Any of you clever people have any thoughts as to what could be causing this and more importantly how I stop it happening in future please?
Be sure you aren’t bottoming out the shank of the bit in the collet before tightening the nut. Instead, push it into the collet until it bottoms out, then pull it back out a 1/16" or 1/8" and then tighten the nut. Failure to do this can result in the bit moving slightly in the collet.
You’re description might imply movement deeper into the collet. Ignore my response if that is the case!
Firmware is 5.03 - I know that this is a bit old, but I have been reluctant to upgrade it as I have heard too many horror stories following upgrades - losing settings etc.
You may be onto something there - the tapered ball nose bit that I used was a very long one and it was the same diameter as the roughing bit so when I changed bits I did not remove the collet so there is a good chance that I pushed it in too far.
Hi all - unfortunately this issue is happening again, during a long 3D carve the Z axis is gaining approx 1.25mm over a 5 hour period.
Today I have tried replacing the collet, cleaning the ball screw, checking that the grub screws are tight in the coupler, checked spindle clamp and the problem still persists.
I am pretty sure it is not electrical noise as the power cable to the spindle is run directly to it and not through the drag chains.
The only thing I can think of is that the problem is with the braked stepper - I am going to try swapping it out for a standard stepper and see if anything changes.
My Z is braked, but I do have the original Z motor so if I dont find a solution I will give it a try.
I am running the same job again now after lowering the plunge rate as I read that if it is too high and the job has a lot of fast Z movement this could cause the issue.