Tune-up and truing
If you have a cable-drive Shopbot be sure that it is calibrated accurately. There is a section in the ShopBot manual
on calibration, and there is also a calibration routine (UC) in the ShopBot software. It's also crucial for good scarf joints to make sure that your Y-axis is as close to 90° to the X-axis as possible, checking with
a framing square or other tool that you are POSITIVE is accurate. Be aware that plywood, even the expensive
imported sheets, does not always have square corners, nor are the dimensions
always accurate. The scarf4mm.sbp and scarf125.sbp files begin by trimming the edge of the plywood, but be aware of this potential problem when you line up the plywood on your table.
