I’m referring to the latter (right and left chain tolerances).
I’ll explain my process more tomorrow (hard to type on phone), but one of my main thoughts is that we really shouldn’t be calibrating the rotational radius.
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No no. I think I’ll ride this out. What the hell. Lol
You’ve brought me this far! 
I’ll go through ur steps for a while longer. Won’t be until Saturday now though unfortunately.
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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: 38.992573So 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.
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I’m in a different boat but going down the same river now. Calibration is totally off and GC assumes the centre of my sheet in the lower 3rd. Distance motor to top sheet was more then 20cm to much and RR as usual lower then my exact 7". Motor distance more then 1 cm to short and I have close to 0 flex in the top beam now. If I correct the distance to the sheet and the RR I get within a cm of Y0 but if I increase the motor distance the sled goes lower again. That should be the other way around. The chain lengths compared to hand measured are surprisingly accurate. I think there is a bug in the calibration that increases going with wider motor distance. I will do 1 more calibration tomorrow and set the chainsag comp. to 0 before I start. Kind of frustrating to have earned the batch of ‘calibrator of the year 2017’ if we had that, and not getting even close now.
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In the next day or two I will be inserting my head back into this beehive. Have modified my top rail to 2 piece 12 foot superstrut that is 6” higher than the original 10’ bar. Since my original chain sections did not match in length, have acquired a 50’ roll from which I will create new, hopefully matching 13’ long chains.
I have been using v 1.13 firm and software. Plan to clear the chip and start from scratch with v 1.19. I have read that there may be problems with v 1.19… any feedback here? Also, I understand I will need to adjust in “advanced settings” the amount of chain that plays out prior to the “sled to home” routine. Any other tips?
Looking forward to rejoining the fray! This should be an interesting (hopefully not sleepless) weekend.
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@Dustcloud I will be following how the calibration goes. I’ve been using 1.18 since I read about the bug in 1.19, just to be safe. But it seems to only effect the startup on windows machines and there is a workaround posted. I will run a second calibration attempt tomorrow, and id that comes out like the one today I will run a third with wiped eeprom and deleted (renamed) GC.ini. Cant’t wait to hear about your feedback.
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I have been absent for awhile myself but I’ll be watching. Other house projects and summer activities got in the way. Need to get my dust collection set up and Maslow only desk cut. Then I should be set to cut some projects during the winter.
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@xrok1, I’ve moved my discussion regarding calibration over to this thread. I’m still working through chain compensation so take a look here. Maybe by the time you get to working on it this weekend, I’ll have some findings to report, but I have to watch the twins the next two nights… will see what I can do.
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