Accuracy issues: off by 1/16" on both X and Y axes


I am using the file attached below to cut the following pattern with a 1/4" diameter endmill:

I’ve encountered a problem: the width of the square is off by 1/16" (3.9375", instead of 4") on both X and Y axes (which tells me that it’s due to some internal parameters). The diameter of the circle is off by ~1/30" (3.5" instead 3.465").

Has anyone encountered this issue before by any chance? If so, then how did you fix it? (2.0 KB)

This just means that there is some error in your calibration or your machine is
flexing during cuts.

first make sure that the motor mounts, top beam, and brackets holding the top
beam are not flexing during cuts (recording video from a tripod zoomed in on
the motors will show even small movements easily)

in terms of your calibration, accurate measurements are a must. see the
side-discussion about class 1, class 2 and unrated tape measures in the topic at

also you may be interested in lookup up the topic “sources of error” (sorry, my
browser is misbehaving, so I can’t pull up the link at the moment)

you don’t say if you are using standard triangular calibration or the new holey
calibration that’s available in webcontrol

for the distance between the motors, did you measure it with a tape measure? or
did you use the chain measurement? if you have an accurate tape measure, it’s
best to measure this as the chain isn’t exactly 6.35mm per link.

David Lang

Hi @dlang, thanks for the quick response. I have measured the distances myself (with a tape measure) and entered them into the Quick Configure settings in WebControl. After that, I used the Holey Calibration three times to eliminate problems with calibration. Will check if the top beam is flexing today and report back.

What accuracy do you get for your cuts?

not as good as you are getting (but I’ve spent less time working on the

David Lang