Z Axis Diving Into Workpiece during 3D Finishing Toolpath

[flynfuzz]

I'm experiencing a recurring problem with 3D carves. With several different projects, the 3D Roughing toolpath completes just fine. But the 3D Finishing toolpath is another story. Usually the 3D Finishing starts out just fine. But at some point, the Z dives into the workpiece, and sometimes all the way into the spoil board.

I've checked all the machine electrical connections to ensure they're tight. I've cleaned and lubed all the lead screws. And I've greased the bearings. That didn't solve it. I installed a surge guard to eliminate any power fluctuations. That also didn't solve it.

I spokewith Chad at Axiom. But he couldn't think of anything that could cause such a problem. And I've sent the problem files to Vectric. But they said the toolpath files were fine.

So I'm at a loss. Has anyone encountered something like this ? I'm wondering if my RichAuto controller is the problem.

[dadealeus]

Apr 11, 2023 21:29:02 GMT -5 flynfuzz said:

I'm experiencing a recurring problem with 3D carves. With several different projects, the 3D Roughing toolpath completes just fine. But the 3D Finishing toolpath is another story. Usually the 3D Finishing starts out just fine. But at some point, the Z dives into the workpiece, and sometimes all the way into the spoil board.

I've checked all the machine connections to ensure they're tight. I've cleaned and lubed all the lead screws. And I've greased the bearings. That didn't solve it.

I have spoken with Chad at Axiom. But he couldn't think of anything that could cause such a problem. And I've sent the problem files to Vectric. But they said the toolpath files were fine.

So I'm at a loss. Has anyone encountered something like this ? I'm wondering if my RichAuto controller is bad.

Hello. Sorry to hear you're having problems with your machine!

The only times this has ever happened to me was because I was running the machine too quickly and while it was fine on my test runs, the z-axis stepper would eventually skip a few steps while trying to pull the spindle up too quickly, resulting in the machine thinking the spindle was higher than it was - causing the bit to be driven too deeply into the project.

It's tempting to run at max speeds for finishing passes since you are removing little material and making quite a few passes - it feels like the right thing to do to shave some time off your projects - but sometimes this can result in skipped steps at random points in your cuts; is it possible that you may have unwittingly done the same thing?

If you've ruled out a problem with the cut path, I'd try simply lowering the feed rate by 25% or so and seeing if it still happens. If it does, then I'd check to see if it's occurring at the same point in the cut path each time (don't rely on the simulation as it doesn't take into account any additional forces due to increased friction, inertia during spindle vector changes, etc.).

Other than that, I don't have any additional ideas.

[flynfuzz]

Thanks for the information. I'll give it a try.

[grossmsj]

Have you actually been there at the machine when this happens? Did you see the spindle actually move down?
I'm asking because the only times I've had this happen it was actually the bit loosening in the collet. Apparently, the bit got enough slack it started moving, then when it got enough it dove into the piece. This didn't happen during a fine finishing cut though, the machine was hogging away pretty good in a roughing mode.
I'm not a weakling, and I don't believe it happened because I hadn't tightened the collet enough. I then ran across this information (https://www.precisebits.com/tutorials/coletcareprocedure.htm) so I decided to clean the collet and the inside of the spindle. This was on a machine that was only about 3 months old. I was sort of shocked at all the grease and crap inside the spindle and collet. Maybe it was there as a result of manufacturing. Anyway, I gave it a good cleaning and I've never had this happen again.
I sure hope you find a solution!

[dadealeus]

Apr 11, 2023 21:29:02 GMT -5 flynfuzz said:

I'm experiencing a recurring problem with 3D carves. With several different projects, the 3D Roughing toolpath completes just fine. But the 3D Finishing toolpath is another story. Usually the 3D Finishing starts out just fine. But at some point, the Z dives into the workpiece, and sometimes all the way into the spoil board.

I've checked all the machine electrical connections to ensure they're tight. I've cleaned and lubed all the lead screws. And I've greased the bearings. That didn't solve it. I installed a surge guard to eliminate any power fluctuations. That also didn't solve it.

I spokewith Chad at Axiom. But he couldn't think of anything that could cause such a problem. And I've sent the problem files to Vectric. But they said the toolpath files were fine.

So I'm at a loss. Has anyone encountered something like this ? I'm wondering if my RichAuto controller is the problem.

Curious to see if you were able to solve the issue. If so, do you know what the cause was?