Just crashed - What am I missing?

Hopefully the answer is right in front of my face. I am cutting a wooden plate for a project – first run cut great, but was a little off from my measuring so I thought I would start over and try again. From the first cuts I could tell something was wrong and about 10 seconds in it snapped my endmill. I keep looking back and forth at each CC file and don’t see any differences that would make this happen. Here’s what I see:

V1 (successful cut) is set as “hard wood” vs “MDF” for V2. Shouldn’t matter as I have manually set the feeds and speeds via the forum spreadsheet. I did reduce the depth of cut per pass on V2, as well as overall to account for measurement on the material. RPMs show different (due to material selection) but that is adjusted by dial on the 611 so I don’t think that matters(?) I am trying to cut from the same piece of plywood as the first run.

DOC: 6.25mm/4.75mm
RPM: 3 on the dial
Feed: 2500
Plunge: 1250

The only other thing that is different is I now have a dust shoe, but it isn’t binding on the collet, and it was adjusted to make sure the brushes wouldn’t hit the material and cause a skip. I’m hoping there’s an obvious answer sitting right in front of my face…

plate v1.c2d (29.2 KB)
plate v2.c2d (57.4 KB)

OK. I went to edit the above to add a detail I thought could be important and the lightbulb went on.

I drew both files as mm in Sketchup and exported to dxf, but when I imported into CC they came in huge. I flipped the units in Sketchup to inches and exported and they came in fine. BUT THEN I DIDN’T CHANGE THE UNITS TO INCH IN CC.

Would that matter??

Only thing that stands out to me is your cut depth is 2x the diameter of your bit (6.35mm is 0.250" and your bit is a 0.125". I’d drop that way down, especially since you’re moving at a feed of nearly 100IPM. Try 1/2 the bit diameter to start, like 0.0625". Using GWizard with those bit/DOC a 20% finish cut is 90/45 feed/plunge and the router is way up at max. This is on MDF.



I was looking at V1, looking now at V2 and DOC is better, but still seems really high for the given bit.


Units in CC are for dimensioning/convenience only.

When importing always verify the overall dimensions

Crashes are usually caused by a mismatch between file and setup.

@DanoInTx Appreciate the input, will keep that rule of thumb handy.

@WillAdams Good to know. I know the file set to inches imported correctly as I sized the CC background to the correct overall dimensions before import.

Figured the only way to suss if it was a file problem or a machine problem was to run v1 again at the same settings as before. Cut just fine. Tried to run v2 again and it was cutting as it should, but the endmill did end up breaking near the end of the job. Not sure what would have caused the aberrant path on the first go round, but I will try again with the DOC set to a more moderate distance.

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