X and Y axis NEMA23 motor mounts on Hobby-Fab / SMW3D plates

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.

I ordered M5x12 regular socket head screws and they are a perfect fit for me. @Brandon_Satterfield told me offline that the slight interference of the LP screws against the motor serves a locking function, but if I need to add loctite I think I’ll just add loctite. :slight_smile:

Separately, for my Z NEMA23 motor mount, I ended up needing 1.5" spacers I didn’t have in my kit (this is my own fault for complicated reasons, not Brandon’s), so I made some spacers out of 5/8" stock I had handy.

Those should be stable enough! (Ignore the non-locking nuts on those screws; they were temporary while trying things out, and have since been replaced by proper locking nuts.)

1 Like

Turns out I’ll have to cut down the side of the rear spacer to accommodate the X pulley, though. Good thing I bought extra lock nuts! I might as well trim the back of the NEMA23 plate for good measure while I’m doing it.

Clearance is…

I took 2mm off the end of the plate, and trimmed the standoff to match. Now I can move the pulley out so that the belt will be straight and it won’t run into the plate or standoff.

I never had a clearance problem with mine.

The instructions Brandon wrote say:

If you chose the NEMA 23 upgrade, … Check the clearance of the NEMA 23 threaded rod plate to the pulley on the X axis. These are sometimes very close; if there is interference then simply file a small bit off the front of the plate.

If I seated the pulley as far back towards the motor as lined up with the end of the motor shaft, there was clearance, but moving the pulley out slightly so that the belt would line up with the gantry wheels they would interfere. It turns out that “I might as well trim the back of the NEMA23 plate for good measure” was only strictly true… I actually needed that “good measure” to line up the pulley properly. :slight_smile:

1 Like

I now note that this means that I can’t move the motor to tension a dual-belt setup. If I decide to switch to dual-belt I’ll figure that out when I need to. :slight_smile:

It turns out that these nice thick Z motor spacers I made are also good for transferring heat from the motor to the NEMA23 plate, which is acting a bit as a radiator and transferring some of it to the X lift 2060 block.