I’m looking at @Brandon_Satterfield’s instructions as I build my OX, and the instructions for mounting the Y motors talk about inserting M5 bolts through slots, as for the plates from OpenBuilds. The plates from Brandon have holes that M5 hardware won’t fit through, and a round registration hole instead of registration slot.
My assumption is that I’m meant to tap the plates M5 and insert M5 screws into tapped holes from back to front, as is common for mounting NEMA23 motors.
I did that, but It looked like the M5x20 screws were going to interfere with the wheels. I didn’t have any M5x12 handy, so I used M5x15 instead of the specified M5x20 and it looks like that won’t interfere with anything.
However, the wide LP screw heads rub against the body of the motor, so I think I’ll replace them with standard socket head M5x12 which should be the perfect length.