This is what I posted in a different thread regarding my calibration and use of chain compensation:
First …
I got half of the test completed last night before the twins came and demanded to go swimming with me. I guess I should enjoy the fact that at seven years old they still want to spend time with me because I know that will end one day.
Chain compensation measurements:
- When measured manually: 3602.6 (Note: this was measured with sled attached and at top center of frame)
- When measured with the left chain: 3590.11
- When measured with the right chain: 3589.66
- Left chain correction factor: 0.347900203615
- Right chain correction factor: 0.360479822602
What concerns me the most is that I’m off by over a centimeter, though fortunately its pretty consistent between both chains. However, if I did the math correctly it equates to about .022 mm per link.
Here are the results so far, with no chain compensation factors:
First calibration run:
- Distance between motors: 3590.11 mm
- Vertical motor offset: 475.8 mm
- Rotation radius: 137.3 mm
- Chain sag correction value: 31.469023
- Vertical error over 12-inches starting near center: 1/16-inch
Second calibration run:
- Distance between motors: 3590.11 mm
- Vertical motor offset: 478.4 mm
- Rotation radius: 138.5 mm
- Chain sag correction value: 27.394203
- Vertical error over 12-inches starting near center: 1/16-inch
It does not appear I can improve upon the calibration by running additional iterations, so I’ll try out the chain compensation factors and see what results.
Next…
Interestingly, I just entered the compensation factors and motor distance and now, without recalibrating, am accurate to 1/32-inch near the center… Just started to recalibrate to see what happens
Finally…
I recalibrated and there really wasn’t much improvement. The values after calibration were:
Distance between motors: 3602.6 mm
Vertical motor offset: 468.44 mm
Rotation radius: 133.2 mm
Chain sag correction value: 38.992573
So I played with the simulator and decided to manually bump up the rotation radius and see what comes of it. I believe (I don’t recall precisely) I added 5 mm to it… making it 138.2 mm.
I then ran a series of 100 mm squares in the top left, bottom left and center and I was getting measurements of 99.7 to 100.1 mm in top left and center and around 99.0 to 99.3 in bottom left. I think this is pretty good.
I’m going to try some projects now (plan to make somethings with joinery) to see how well it works.
So, I just looked at my groundcontrol.ini file and am very surprised to see my rotation radius is still 133 mm… I’m confident (or at least was confident) that I changed that and don’t understand why it’s not 138 mm… hard to imagine I changed it back. My values are:
Distance between motors: 3602.6 mm
Vertical motor offset: 468.4 mm
Rotation radius: 133 mm
Chain sag correction: 27.394023
Left chain tolerance: 0.347900203615
Right chain tolerance: 0.360479822602
Seeing this, I need to do some measurements on the project I just did… I think it may be off… man, I hope it fits over the stovetop… sigh.