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I'm cutting templates for a neck and fretboard and I'm experiencing a strange problem. The cut doesn't match the design. The curves at the end are supposed to be symmetrical, and one corner is sharper than the other, on both pieces!

Here's the design, 1:1


And here's the results:


So, what am I doing wrong?

is your model angled in the real world?

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Ken

You mean the outside edges? Yes. One is a template for a neck and the other is a template for the fretboard that goes on it, so the edges are not parallel.

To me, this looks like a Mach 3 corner rounding error. Is the acceleration on one axis significantly different than on the other? Is your acceleration on the lower side? Are you running CV mode?

If it is indeed an acceleration problem, you can fix this by lowering the lookahead parameter in CV mode. I also have mine set to exact stop on angles over 85 or something like that but that won't help in this situation.

Usually this error shows up on sharp corners when running a relatively (to your acceleration) high feedrate. It's less common for this to show up on round corners like this but if the acceleration of your X & Y axis are significantly different, I think this could show up.

If I was a betting man, I'd say that the acceleration on whichever the long axis is on your template has a significantly lower acceleration than the short one. I'd also bet that you're conventional cutting (CCW around the perimeter)....judging from the look of the cut.

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Thanks, Andy. Some of these parameters I will have to check into, but I can easily slow down the feed rate to start.

Update - I reduced the 'look ahead' from 20 to 5 and it worked great! Thanks again, Andy!