Everything Is 1/32" Too Small

I have a new X-Carve with the 500mm rails and DW611 router. I did all the tuning steps I thought were necessary: adjusting the motor pots, tweaking the step size to move the router an exact distance, etc. And things seem to be working pretty well, except that whatever shape I carve seems to come out 1/32" too small. It is not a scaling issue since, for example, a 1" square and a 5" square both come out small by the same amount. I have made shapes directly in Easel and also imported G-code from VCarve and get the same results. The shapes come out very consistent, so I’m not losing steps, etc. I measured the bit diameter and it is exactly as specified. What am I missing?


What size bit are you using? Is it possible you are cutting on the line versus outside?

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It was a 1/4" bit, so that wasn’t the problem. I did check that I was in the right position relative to the line.

I had a similar issue early on and to fix it you need to adjust the variables $100, $101 and/or $102. I don’t remember how far each variable change is, but there was a thread about it on here somewhere. Anyway those settings fixed the issue for me (sorry I couldn’t be more help but it was like a year ago).


Thanks for the replies. As I said, I checked both those things. The bit measures exactly 0.250" with calipers; I will double check and try another bit to be sure, because that seems like the most likely thing. I adjusted the $100 and $101 values and get the correct movements in each axis. Plus that should make a 5" square smaller by a different amount than it would a 1" square since it sets the scaling.

I remeasured carefully on the cutting portion and it is 0.246", so it is a tiny bit small. I will try your test when I have a chance and also try setting the bit size to the exact measurement, and also try another size bit to compare. Thanks for the tips.

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Don’t measure the actual bit (no matter how careful you are, you can damage the cutting edge) — instead, cut and measure a slot.

To continue that, you could cut a diamond-circle-square test block and evaluate it to determine the runout for that endmill in that spindle, in that machine.



Finally had more time to investigate this. After measuring the width of a single line cut from the 1/4" bit, it does indeed measure narrower than 1/4" by about the required amount to make the cuts I was measuring too small by the amount I saw. Thanks for the help!