Improved Calibration Technique?

I want to call attention to some good work that community member “DomeDave” has been doing. He has created an alternative script for calibrating his machine based on his past work doing calibration for optical systems. His technique is similar to the holey calibration approach, but also somewhat different.

You can read about his techniques here:

And find a copy of his calibration script here:

Just wanted to make sure this one didn’t fly under the radar.



So no new firmware or anything? Just run a gcode program that barely dots the workpiece, measure the dots, input the measurements and get a new groundcontrol.ini?

I think I know what I might be trying tomorrow. :grin:

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Yup! It’s a totally stand alone technique.

I would love to get some feedback on how their system stacks up against the original calibration system.

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I am really interested to hear some feedback on this from our more experienced/knowledgeable technically savvy users.

I’m not a pro user, but it looks cool

Welcome to the discourse!


I love the idea, very similar to techniques used to calibrate 3D printers, except due to polar co-ordinates, insanely more complex.

I had a look at the code, which makes reference to “input measurements file in .ini format (see example file)”. I didn’t see the example file in github.

  • Is it there?
  • Did I miss it?
  • Can anyone else see it?

thank you @ShadyG, glad to be here


Does anybody have a copy of the script he mentions on his post? He used this to determine the values to input back into the .ini file

The scripts can be found following the github link in the first post

WOW!! I cant believe I completely missed that! LOL

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How is this different from the Holey calibration? It seems to function the same way.

I can’t tell what a closed loop calibration is and did not hear of anyone testing it.
The claims Refine calibration are having written it because of experience calibrating optical devices and reaching under 2mm error as a result.
Cutting on masking tape is tempting, rather then using wood-filler :slight_smile:
Sadly no instruction manual…

Edit: I got a little further.


sends a clear message that 3 parameters need to be given:


So the correct command would be something like:

python3 groundcontrol.ini, measurement.ini, groundcontrol-mod.ini

But with commas as separators or something else?
The first and the last argument are clear, but there is no clue on the format the measurement.ini should have other then it should likely have 9 lines with the measurements (left and top) for the cuts.
Short journey…


Has responded to 2 Maslowians commenting on his blog. We should receive a sample of the ‘INPUT_MEASUREMENT_FILE’ soon. It somehow did not make it to github.
The syntax of the command should be with the variables separated with a space. like

python3 groundcontrol.ini measurement.ini groundcontrol-mod.ini

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I could use a little help here. I have copied and saved the file contents from Github and am trying to just run a test on the files (including the sample cut info provided). This how I call the script and the result as an error:

python3 groundcontrol.ini measurement.ini groundcontrol-mod.ini

File “”, line 1
python3 groundcontrol.ini measurement.ini groundcontrol-mod.ini ^
SyntaxError: invalid syntax

I am lost with python and would appreciate any clues as to what I am doing wrong. Thanks!

The originator has said he would publish the missing file. Let me check if he done so and if not send a second request.

I finally was able to get Python to successfully process my sample files. Pretty neat!!!

Has anyone been able to use the g-code file provided by DomeDave and successfully run the calibration? Just wondering about your experience(s).