Not sure I understand this. Do you mean that a 100mm square would be 100mm x 100mm but would be located 5mm higher or lower than expected? Or would the square be 100mm wide and 95 or 105mm high?
I’m refering to top of top square to bottom of bottom square and distance between center marks in the Y as well.
Just had a new idea, my sled is only 20lbs so I’m adding another 20 to see if that helps. Possibly straighten the chains a bit.
another 20 is that pounds? you will face problems cutting at the top of the sheet. Add 10 max as a ~ target 
With my 16.4kg ~ 36.15581 total sled weight I am the second or 3rd heaviest I think.
added 10
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I’m on my phone, so not sure exactly what the menu option is, but you can go to actions and then select to run just the triangular calibration cuts… might be under advanced button in lower right corner… you’ll find it.
well that was a disaster! sled would’nt keep up. removed extra weight!
Well my circles are round now!
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Now i’m totally frustrated and lost! Made a 900mm square with a 900mm circle in it in fusion. Its 904 in the X and 910 in the Y. I don’t know what to do. Problem is its repeatable but don’t know what adjustments will fix it!
Running out of scraps to test with!900MMsquare.nc (1.5 KB)
What is your rotational radius and chain sag values? And are using the chain compensation factors?
Just redid full calibration. Seems a lot closer now but I’ll run a few more cuts in the morning.
Thank you SOOOO much for your help @madgrizzle
Rotational radius is 123.3
Chain sag correction value 56.382947
Don’t know where to find chain compensation factors. Is it chain tolerance in advanced?
If so its left chain 0.462849578537 Right chain 0.463472478415
I think there’s a problem with the calibration routine (or something). My opinion is that if the rotational radius doesn’t end up close to 140 mm, you won’t have good results. Save those numbers, but try this and see how it works:
- Set chain tolerances to 0 ( you can find them in settings) but leave the distance between motors as you measured it.
- Set rotational radius to 140 mm (in settings)
- Run triangular calibration twice (access this via the actions - advanced menu)
- Run your test cuts
- Set the chain compensation factors to what you recorded.
- Run your test cuts
- Compare results
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Rotational radius shows a default of 100? Shouldnt it be default 140? I’m using the ring.
BTW is there a way to backup my settings before I play around or do I have to write them all down?
Make a copy of groundcontrol.ini store it in a different folder or rename it like groundcontrol-old.ini
Most (all?) settings are in there.
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Or are you refering to this 
which is set to default (140)?
OK thank you!
Yes, set that (Rotation Radius for Triangular Kinematics) to 140 mm. I think I brought up changing the default from 100 at some time, but nothing came of it. I don’t know any ring/linkage kit with a radius of 100 mm…
Yes, you can backup the settings. make a copy of groundcontrol.ini If using windows 10, its /users//groundcontrol.ini
Follow all your steps up to 4 and results are good! Bang on in X only 5mm off in Y but consistent along the Y for the first time!
Rotation radius went to 136.1 and Chain sag correction went from 56.38 to 28.69.
Moving to step 5, fingers crossed.
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Way worse! 913 in the Y and 1888 in X
Can someone explain what the Chain sag correction value is used for? Maybe I can tweak it?
Are you saying by just entering the chain compensation factors for left and right chain that a 900 mm square turned out 913 mm in the Y and 1888 mm in the X??? Check your compensation values… make sure they are entered correctly. You posted the values here