Hi David,
I have been tinkering as well, and it appears that I have made a mistake about the optimal frame size. I said 4500x3800, but that is too large.
If we allow for rotating of the sled, the limitting factors are:
Opposit arms have a Minimum angle of 130 degrees, the corners of the workarea get affected by this.
Adjacent arms have a Maximum angle of 140 degrees, the middle of the long sides get affected by this.
I put that in a sketch:
and I get an optimal frame size of 4492 x 2855. I didn’t check, but is this what you get in your spreadsheet?
I don’t know how to put this method in a formula or a spreadsheet, but graphicly it is easy to do.
of course if the dead zones could be made smaller, the optimal frame size could be smaller too.
Arjen