How to calibrate this damn device?

this part must be 60mm high

with a test cut, I got 61 mm on one side (a good result),

and on the other hand 64mm

about internal cuts, they should be 15mm in width

in fact, one 10mm, the remaining 12mm
the actual length of the workpiece is 3mm less
I’ve been trying to calibrate this device for almost a year now. Unfortunately I do not have a place where I could place it. I rent a room for him and pay a lot of money. but so far I have not received the desired result, but only new problems. Who really can help calibrate remotely through the teamviewer program ??

While teamviewer can help upload the firmware and install GC, for calibration it’s not useful i think.
Machines that can’t be good calibrated have often mechanical issues, that can only be discovered in front of the Maslow or by pictures and videos.

Accurate measurements is the next to take care of. (better 3 times measured then 1 time wrong)

  • are your motors level, how did you check?
  • do you have a flex in the top beam or on the motor mounts?
  • do you have a helper to measure the motor distance by hand?
  • how confident are you that the ring? is exactly centred on the router-bit?
  • have you changed from bungees to weight system?

The software is attempting to get the measurements of the Maslow for you, however there are a bunch of reasons the software can get the measurements wrong. Is good to check the numbers from the calibration with what you measure by hand and if you think the software is off to far, replace the calibrated values with the hand measured ones. Main values with the names in the groundcontrol.ini are in this picture:

If you change settings in GC, it’s recommended to close GC after the changes, un- and re-plug the arduino, start GC again and check that the changes are still there, before moving the machine.

Take a look at the holey-triangular-calibration. It runs a different FW and GC and has been reported to give great results.

P.S. I’m calibrating 2 years and 1 month (only few hours every weekend). I’ve modified my frame 3 times making it level and stronger. I’m running my 3rd sled now. I’m still not in the 1mm i want, but getting closer with every modification. I still call it an incredible machine, rather then a ‘damn device’.
The link above (holey calibration) is what i’m testing next. Good luck and heads up.

Kind regards, Gero


I will admit that, as a person with no prior cnc or 3d printer or arduino experience, calibration was difficult for me. It took me about 6 attempts to get through it one time without messing it up and needing to start over. Having a good understanding of how Ground Control and the firmware work is helpful to know how to make calibration, recalibration and operation work easier for you.

As gero said, TeamViewer is really only half the picture, or maybe less. Have you been using the calibration wiki? That was a game changer for me.


How long until the Holey calibration will be usable to those of us with no programming experience?

The pictures in the first post are not working for me (it looks like you may have hit post before the uploads finished)

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Since this is all open source, it’s being developed by generous people who are doing it in their spare time. It is very close, though IMO.

@Gero, what’s that famous person quote about patience with cnc?

I think the problem is just the packaging/installation.

whatever is being done with the standard Ground Control to make the .exe file
needs to be done with the holey code.

Once it’s installed, it doesn’t need any programming experience just like the
standard Ground Control.

David Lang

“CNC woodworking is not for the impatient.” -Alma Maria Mahler Gropius Werfel :slight_smile:


Спасибо за обратную связь!
•the level of the motors was measured by a long board.
•we do not have a deflection of the main beam, •we have replaced it with a metal one

the distance between the engines measured, differs by several mm
•I’m not sure what exactly the center, try to make a new sled
•about the scales, I do not know what it is, maybe my translation into my native language is not correct.

thanks, added

when you say you aren’t happy with the calibration, what sort of accuracy are
you getting? how far off are you from ideal?

what version of ground control and the firmware are you using?

David Lang

I can offer that this is a common experience… don’t be alarmed if the distance measured by the machine is different than what is measured by hand.

deviations of 3-5mm (in the first post I added a photo) impossible to get circle a straight part and a circle in fact I get an oval or parallelepiped instead of a square.
Ground Control 1.23 version

After I see your picture I see what I may be doing wrong with my calibrations. I will try that again.

I am getting small circles (3") not round. Last time 2.3125 was off about .080". Not sure it is the Calibration yet. I will measure it this time.
Thanks for the Picture,