Calibration difficulties

Hello all,

I’ve gotten the ArcDroid and cutter setup, went through the calibration routine (multiple times), and tested that the whole thing can cut a circle (it does!). However, I am having difficulty with getting the calibration to within the 0.05mm across 313mm. I didn’t find anything addressing this in other posts but I relied on the search function for that.

I’ve gone through the process multiples times. I think I’ve identified any potential play and payed attention to the tips from Amp Mechanic’s “ArcDroid: Initial look and setup calibration troubleshoot tips” video (perhaps I’ve missed something). The arms locked up after sending M17 through the G code terminal. I checked the firmware today and it is dated December 5, 2022. I didn’t note the version number and I also see that there is now a January 7, 2023 version.

The largest discrepancy I noticed is that across bar 2 (Y axis?) there is a ~4mm difference. I didn’t check along bar 1.

The USB stick was deleted of all other data before use, already formatted to FAT32, 32Gb in size, and was formatted by the ArcDroid computer at some point in my attempts. It is old, as far as thumb drives go.

Any ideas for what to check or try are welcome.


Are you checking the torch or the stylus? And do you have the stylus or the calibration sled plugged into the machine 3.5mm jack?
Having stuff plugged into the jack changes which tool offset is used, stylus vs torch.

Make sure you’re checking the torch with the jack unplugged, or the stylus with the stylus plugged in.

If you’re still getting large errors, try the calibration tips from this thread

I’m not sure the Arcdroid has enough resolution to be within 0.05mm. My experience has been anything around or about within 0.5mm is great.
Glad you’re getting some use out of the videos. A lot of what’s in those first couple videos may not be relevant to current firmware versions. I was addressing problems at the time with the first batch or two of machines.

iyeremin has some good advice above. Good luck!

That makes sense and I was not doing that. It makes a difference and I am at 1mm or less on my readings.

One other thing: When I raise the stylus after running down the first rail the arm will shift to the side a little bit. It’s as if there is some roughness in the movement that the arm is settling away from. I just watched the belt tension video and I’ll take a look at that. See what happens.

Sometimes the tension thats in the cutter cable will pull and give the appearance is a jump movement. Ive seen this happen and occures when the motors are de energized after the job is done. If your seeing it jump while inbthe program that is another issue.

I haven’t seen that. This movement is happening after moving the arm manually and then raising the stylus off the calibration shuttle.

I got a new USB stick (and updated the Simple Trace OS and firmware) and did another calibration. The X axis is good but the Y axis is out by just over a millimeter. This is consistent with my previous calibrations. One bit of trouble I am having is maintaining movement while sliding along the rails. The roughness in the arm movement and perhaps my own coordination means there are pauses in forward motion but no backwards motion. Could I be going too slow?

If you’re getting jumpy movement you belts may be too tight
try backing them off a little (I like to back off a little at a time till loose and then retighten)

Se my quick YouTube short on adjusting
Proper Belt Tension (reupload) - YouTube


I adjusted the tension and the arms feel much better. Calibration is closer, too. I did not use your method of adjust until loose and retighten. I’ll try that next.

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