More information about the calibration benchmark test

I just downloaded, tested and it works.
It should be in the folder -> gcodeforTesting

Which operating system are you using? It might be the case that the macOS or Windows package is at fault.

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using a Mac. I suspect that is the difference. I did not see a folder in the contents of the application package with that name. anyone know the Mac path?

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I looked at an older GC on the mac and the files are not there.
Calibration Benchmark (567 Bytes)

You can get more attention opening a new topic under the troubleshooting category with a speaking title like : “Benchmark .nc not found on mac” or so :wink:

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Thanks for the detective work, @Gero, I’ll find the cause and get a corrected version ready.

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Just made sure it’s the same with 1.16 :slight_smile:

I opened issue #736 and PR#737 for this. The package-building software needed to be told to include the ‘.nc’ files of the gcodeForTesting directory.


I remeasured. Average of 6mm off. Mostly in center and top left Y being 7mm and 6mm everything else is within 2mm. :crazy_face:
From upper left its 6mm, 7mm, 1mm in Y (vertical) and
0mm in X (horizontal).
Any ideas why?
FYI the sled is staying level for all cuts.

@bar, I feel silly but I’m missing something here. I get the 1.16 average shown in the example above but how should the two different numbers be calculated?

The first number is calculated like this?


…meaning the 100 mm squares? Is the second number calculated the same way but using measured - expected width and height for each square?

Is this right? Note, the “Big Sq2” and “Big Crl2” are for a test cut that I made (concentric squares and circles that are centered just further out from the 100 mm squares).


You got it! The second number is measured exactly the same way except that all of the expected values are 100.

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What are you guys using to measure these distances? I feel like a standard tape measure is too inaccurate, or rather the human eye

the small squares are able to be measured with a cheap digital caliper (similar
to )

longer distances are with a tape measure.

take a look at the ‘in search of accuracy’ thread
In search of accurate measurements where I
am working on a 3d printed part to pair up with a tape measure to get sub-mm
accuracy. I used a set a couple days ago and it worked well and was
substantially faster than just using a tape measure (or so I’m told by someone
who has calibrated more machines manually than I have)

David Lang


I have an interesting idea about measuring longer distances accurately. Assuming you can accurately place the ends, and have enough people or clamps to hold everything in place. Take two tape measures, one metric and one imperial. Extend them from the endpoints so the meet in the middle. Then carefully look at the marks on both measures to find a pair of marks that align precisely. Record the two lengths, convert the “wrong” one to your desired units, and add them up.

The idea is based on a vernier scale, which is a very precise way of measuring distances used in things like calipers. Well, it was until dial and digital calipers came along. This is not a vernier scale, but I think one would still be able to find a pair of marks that line up and get a very accurate measurement.

take a look at my recent work at


I was hunting a thread remarking what the different size squares/location might mean without luck… anyone?

Short story- everything was working fine till I pressed the upgrade Ubuntu software button and my relic Dell 32 bit laptop became obsolete.

I did try a new Ubuntu 19, but no longer supports our Kivy…

I took advantage of my “if it ain’t broke, don’t fix It” mistake to raise and lengthen my top beam and bought a used Dell 18” XPS touchscreen, which the touchscreen part I can confirm works really well with ground control, and would recommend, as others have posted before me.

I am now running Windows 10 pro, and 1.26 GC.

Fast forward to two full calibration attempts and I’m close, but can’t seem to get any closer:

Horizontal is dead on, 1905 x3. Luck perhaps.

Vertical left to right is 896, 893, and 894.

The two left squares are within a mm 100x99.

The two rights are 100 wide and only 94/95 wide.

It didn’t seem to affect my first two real cuts… Any guesses?

The rotational wants to calibrate to 127 +/- (from 139, my measure) on both calibration attempts, but in settings it still says 139. Not sure if that’s meaningful.

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@Kurtsea it is important to understand the area of the Maslow is not linear, the accuracy changes depending on where you are on the Maslow. I hope @dlang can point you to one of the threads that shows this. The area in the center is more accurate than the sides. So depending on what you cut where your accuracy may fall.

Thank you

Update. Looks good again!

I recalibrated using a physical measurement of my top beam instead of chain length and went back to my original sled (felt like the ring was off…)

Measurements now super close to listed parameters above. Squares are dead on 100mm. Distances are a touch long 902-3 and 1906/7.


Super pleased.

Hope that helps someone else.

PS I made my sled with 3/4 starboard and put an 1/8" 45 degree straight bevel on the perimeter edge. Slides nice over plywood.

Thank you everyone for your help.

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This entire comment thread is over my head :cold_face: I feel like I’m reading Stephen Hawking!!

Welcome @a1graymatter! Some of the conversations here get pretty deep into the technical details. Keep reading and you will start to pick up what people are talking about.

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It’s the Flux Capacitor, Turn it off and on again.

Thank you