the code is opensource on github
I won’t pay autodesk for their software as they refuse to consider it a sale.
part of the problem is that there are just so many unknowns involved, for
example, on the chains, what is the gap between the pin on the chain and the
hole it’s rotating in. If it varies by 1/1000 of an inch then the chain length
can vary by 1/2 inch once you feed out 500 links (the 10’ of chain to reach the
opposite corner), the weight of the chain (and therefor the amount it sags under
any specific tension) will vary from manufacturer to manufacturer.
The holey calibration routine is designed to be based on the diagonal
measurements. the errors tend to be symmetrical around the center of the
machine, but (depending on the chains and the motor mounting) may not be eactly
the same on each side, so you can’t just go from one edge of the workpiece to
the other edge (and how square is the workpiece? and how precise are it’s
dimenstions) I understand that one of the newer kits includes a different
calibration routine that doesn’t drill holes, it may use the edges of the
workpiece. I have not looked into that in much detail.
here is the thread on sources of error
part of the fun in designing a calibration routine is that the errors almost
never manifest themselves as linear errors, they tend to be curves (up/down or
left/right) and different error sources can result in similar looking error
curves, so figuring out which of the many things is in error to fix is an
unsolved problem. The current holey calibration only tweaks a few of the
settings to try and correct the error. It tends to do a pretty good job, even on
the first pass, but depending on your measurement accuracy (see the tape measure
discussion), it may improve things to re-run it a couple times.
David Lang