Is the motor height above work surface measured on the 15° plane (eg along path of the chains), or vertically?
vertically from the top edge of the working area to center of sprocket (if you measure to bottom of motor add 20mm)
No, it’s measured along the plane of the workpiece (it’s offset, but you want to
mearure it as well as you can as if it wasn’t)
remember, you are measuring for the chains, and they are all along the plane
parallel to the workpiece, offset by the height of the linkages on the sled
(which ideally matches the location of the top beam)