So it’s getting colder out, -10 this weekend, but there was milling to be done! Motor mounts are done after some boring boring and exciting slotting. I had sketched the initial dimensions and used Autodesk Inventor to ensure appropriate spacing for the belt drive. Below is a quick and dirty CAD model showing the belt drive, stepper mount, and pinch bolt arrangement. The spacer meant for mounting the stepper motor didn’t end up working due to pulley clearance. The plates mounting directly to the mill remained the same with the addition of 2 tapped holed on the top surface. You can find out what the final assembly looked like in later posts.

Starting with some 3″ x 1/2″ flat bar, a hole is bored to fit around the thrust bearing housing for each axis. A 1/2″ hole is drilled in the right spot and the boring head is slowly jogged out until the inner diameter of the hole matches the outer diameter of the thrust bearing housings (1.25″ on Y, 1.29″ on X and 1.80″ on Z for anyone who is interested). The diameter isn’t critical since the mating surfaces on the thrust bearing housings are painted anyways and I’m going to be pinching the diameter sown slightly.    

Forgot to mention the 1/4″ hole which was cross drilled 3″ through the flat bar. That was actually remarkably easy with nothing more than a centre drill and cheap Mastercraft drill bits. The back jaw of the vise had also been skimmed prior to drilling.

Back to the boring part, a successful 1.80″ hole was bored after a few minutes.

After some slotting, the hole has enough relief to be “pinched” slightly by a 1/4″ bolt. There was no particular calculation behind the length of the relief slot, but it works.

More slots are added for mounting the stepper motor and allowing for both adjustable belt tension and easy installation.

Test fit on the Y axis was successful. The fit was snug and there is enough clearance for reaching the stepper mount bolts from behind. The addition of the pinch bolt really solidifies the setup. This was nice and unobtrusive, so I will be less likely to run into issues with warranty claims if any come up

Identical fit for the X axis. The mount was placed on the left-hand side of the machine since the right side takes most of the thrust load from the lead screw.

Sorry for the blurry photo below, but it’s the same story for the Z axis.

The conversion process is coming together nicely. My stepper motors, drivers, and power supplies have arrived from Wantai motor and Digikey, but I haven’t had a chance to play with them yet. Currently I’m still waiting on pulleys and belts from Ebay, CNC action coming shortly.