Random grooves in finishing passes

[Anonymous]

I have this strange occurrence that has happened on several cam models.

Using a finishing tool path (Parallel) both directions, I am getting these deep random passes when controlling my cnc with UGS. You can see in the pic the deep grooves both x and y. If I run the toolpaths again it happens in different spots but they are 2 mm deeper than their neighbor. It is a spline model turned into a solid. I dont see anything odd in simulation.

Any ideas on what might be happening?

Thank you,

Ron

[HughesTooling]

Are you using smoothing in the OP? Are there G02/03 moves in the XZ and YZ planes and are you using R or IJK for circle centres? If the sim looks OK you need to be looking at the control or a mechanical problem. Just as a second level of checking the code have you got a back plotter like NC Corrector so you can inspect the actual G code.

The problem doesn't really seem mechanical as you'd get a depth change for the rest of the run, not just a groove. So I'd be looking at the control software.

Mark

[Anonymous]

Whoa...I should say I'm a beginner...all of your reply (much appreciated) went way over my head.

[Anonymous]

Are you using smoothing in the OP? -Yes

Are there G02/03 moves in the XZ and YZ planes and are you using R or IJK for circle centres?

-I dont' know what these mean...Im am running a standard 3 axis cnc

If the sim looks OK you need to be looking at the control or a mechanical problem.

-I Will double check the sim. I don't think it is mechanical because the next pass goes back to the right height.

Just as a second level of checking the code have you got a back plotter like NC Corrector so you can inspect the actual G code.

-I will take a look into that

The problem doesn't really seem mechanical as you'd get a depth change for the rest of the run, not just a groove. So I'd be looking at the control software.

-Agreed. I thought Universal G-code sender was a standard?

Should I try using Scallop TP instead of Parallel for the carved top?

[HughesTooling · Accepted solution]

Try tuning Smoothing off. G02/03 are arc moves and some controls struggle if they are on the XZ or YZ planes. Arcs can be defined in the g code as end point + circle center(IJK) or endpoint plus radius(R) Radius is vague and I would not use.

Mark