Recognizing the results of calibration

Hi everyone.
I had several calibration sessions that showed me different results.
Unfortunately I couldn’t find any relevant guide/documentation to recognize these results.

So here are the results of 2 holey calibrations (performed in 30 minutes), without any changes in mechanics

Could someone say are these results acceptable or not?
And why are they so different?

Any help is appreciated!

WebControl 0.94 (single directory on windows 10 x64)
Holey Firmware 51.27
MaslowCNC v1 (with 2 heatsinks)


the only way to know if the calibration results are good for your machine is to
try cutting something and see if the results are good enough for you (what is
acceptable when doing panels for christmas yard decorations is not acceptable
for furnature for example)

note that you can get different results in different areas of the sheet, so try
cutting a square near the center and near the four corners, checking each one
for correct dimension (including if the height and width match)

David Lang

You said you did 2 calibrations. If you put in measurements both times you would get different calibration results. Or am I could misunderstanding what your asking.

as @dlang stated, you’ll have to do some testing to see if your calibration results are where you want them to be. Another way you can check without having to cut is to mark your spoil board at the edge of your sled, using WebControl to move your sled a certain distance (e.g. 12 in), then mark the spoil board where it stops on the same edge. Move the sled out of the way and measure the distance between the marks. If it is equal to the distance you commanded, then you should be in the ball p[ark of where you would want your accuracy. Do this in multiple directions (up, down, left, right) to ensure you are good, and again, as @dlang stated, do it in multiple areas of the spoil board. Recalibrate as necessary. Adding in the cutting can help to see if you are getting any “natural??” deflection from the bit having resistance from the cutting process.

Sorry for the late answer.

@dlang I performed several cuts right after each calibration session.

  • 1 rectangle (30cm * 80cm)
  • 2 circles (20cm diameter)

Rectangle results looks pretty good to me, because I’ve got almost same results along the entire length.

But the results of circle cut looks a little bit different. If we slice the circle into 2 parts as it described on the pic
“part A” is not ideally rounded. Upper part little bit “eggy”.

Also there is an another issue, maslow adds to models dimension (in any direction) approx 3-5mm to the final result.

I mean if I want to cut 20cm diameter circle, maslow cut it with 20.5cm.
The same behavior is for rectangle. Model dimensions are 30cm80cm but the results on the wood is 30.580.5. I also checked (several times) GCode generated by CAD software (i use ArtCam for this purpose) line by line and didn’t find any issues on it.

@TimS Sorry, my English isn’t so good to explain my issues from 1st try :pensive:

  • I completed holey calibration (try 1)
  • note values as well as calibration results
  • got calibration results and accept them (picture “Result 1”)
  • make circle cut
  • go to the holey calibration menu
  • put previously noted results of holey calibration (M1-M12) into text field
  • click on calibrate but get absolutely different results (picture “Result 2”)

@c00nphrog it’s a good idea to measure movement and match distance. I haven’t tried it yet.

Here are a some additional pictures of my setup (sorry for dust)

If you keep entering the same measurements for successive calibrations, you will get different answers. Once calibrated, you need to cut and measure again to “dial it in.”

As I understand it, the calibration offsets will adjust from the current settings to make it more accurate. If you reuse calibration numbers, the offsets should make it worse because they were from the system’s previous settings.

I’ve also found this post with similar issue, where cut size doesn’t match model size

So I’m going to re-check all calibration measurements again.

I’m also looking for the way to correct measure “Height of Motors Above Workspace”.
Could someone say is there any “user friendly” explanation of this?