when I cut rectangle or circle ，alway small almost 0.4mm, how can I calibration? Attached photo, I cut size is 15mmx51mm, anyone can help me?
If that’s the machine and not somehow a different setting, you can calibrate it. Somewhere on the forum is a post documenting it. I think it was cyberefguru or something like that who posted it. Try searching.
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Here is the method I used.
I used my endoscope but the procedure and math is the same regardless.
https://youtu.be/7UsFWfy-J6k
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Make sure your tool measures exactly what you enter for the tool, I bought a few 1/8" end mills, advertised as such and labeled the same way but they were in fact 3MM not 1/8"
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Hello Saemonz, welcome to the forums.
Yep, I wrote instructions for the BB controller - not for the Masso.
That said, in my experience, you shouldn’t be that off just because of tuning of the stepper RPMs.
Are you positive your bit diameter matches the diameter in the CAM file, and you are cutting on the correct “side” of your vector? That is, some programs let you cut on the inside or outside or middle of the vector. I just f’d a $1500 custom table build when I hurried through the settings and cut 19.75 circle instead of 20" – any guesses what size bit I was using 
Finally, from the picture it looks like your inside contour has some dog boning, so perhaps there’s more at play here. More details like what bit you are using, feeds, speeds, DOC, step over, and CAM software would be helpful.
-Tom
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tom
I use BB controller, I calibrate xy according your post, and setup motors 0 and 1, xy move is accurate
I use 1/4 jenny compression (I have change new one same result) and software vcarve pro , BTW in my design no dogbone, when cut inside , look like have it , vcarve version 12
attch vcarve setup
