We find ourselves at a point where the saw is cleaned up and the motor starter is reworked and functioning as it should. My problem now, is the lack of motor in it. The machine originally had a three phase 1hp motor, which appears to measure out to be a 184 frame, based on the mounting plate in the saw. I picked up a 1.5hp single phase motor to replace it. The issue being that my motor is a 56 frame, and the holes don’t line up with the existing bracket in the saw.
Why don’t I just drill some holes in the bracket and be done? Good question. The thing with that approach is that the back set from spindle to mounting holes on a NEMA 56 frame spec is not far enough top work here. To get the motor far enough out so the pulley lines up with the drive shaft pulley, the front holes of the motor would no longer be on the mounting bracket. I think we can agree that running it with only 2 bolts on the rear of the motor is not advisable.
My solution, is to create a custom plate that the motor bolts to, which then bolts to the existing bracket. A NEMA 56 to NEMA 184 adapter plate, if you will.

This is the starting point. After measuring, designing and prototyping (plywood), I began work on a 1/2″ thick chunk of aluminum for the motor bracket. My CNC is just an upgraded wood router based CNC, so steel or cast iron wasn’t really going to happen at this scale.

The first run at making this part could have been better. I was trying a new bit specifically for roughing in aluminum, and I don’t think I’ve quite dialed in feeds and speeds yet. I was getting some chatter when it was doing this finishing pass, so things were not so great when it grabbed and put a few divots in the edge. Though I could “live with that” (by likely filing the edge down to hide them).

In the process of digging in, the X axis belt must have skipped as well, because it started to cut in way too early. At this point I hit stop, and took the part out. Ouch. Didn’t intend to waste that much aluminum, but that’s why I ordered enough for two attempts.

I made some adjustments to the CNC as well. I tightened up some of the v-wheels on the z-axis carriage that seemed to have play in them, as well as an overall inspection and tightening of the rest of the machine as well. I also made some updates to the model and tweaked some feeds and speeds for the second try.

For the second run, I dialed it back a little bit on aggressiveness, despite having been conservatively following the manufacturers recommendations before. I also used a bit more WD40 while cutting, to try to help. So far it seems to be doing the trick, but we didn’t run in to that much significant trouble until cutting it out last time (the full width slot cutting was tough).

Well, we made it! It successfully cut out, and while the surface finish wasn’t perfect, I was pretty happy with it at this change. Time to finish it out.

After the roughing bit, I did a clean up pass all around with a finishing bit to get it in better shape. I also ran a chamfer pass afterwards to clean up the hard edges, though this would actually end up being the bottom of the plate in the end. I’m pretty pleased with how this one turned out, though I’m sure a professional (or more enthusiastic enthusiast) can point out many areas for improvement. I’m still learning 🙂

A little bit more on the design of the plate itself. As I mentioned previously, this is the bottom of the plate. These slots with the clearance is for some 5/16″ bolts. The counter bored area is large enough for the bolts to slide, but not turn. I had thought about picking up some square headed bolts so this would be a little stronger, but I didn’t want a whole bag of them just to use 4. This is so that I can adjust the motor positioning if I have to, without removing the whole thing from the saws motor mount bracket to loosen/tighten bolts.

The 4 holes on the outside are clearance holes for the bolts that will attach the plate to the saws motor bracket. These are not slotted, because the motor mount bracket itself is. It will let me move it to help get it aligned with the pulley, and then I can fine tune it by moving the motor in its slots instead. This is why the bolts were counter bored on the other side, because this had to sit flush.

That was the plate done, so now it was time to get it bolted up to the motor so I could install the whole thing in the saw. I also wired the motor up to the starter and overload protection at this point too. Nothing special there, just followed the wiring diagram for 220v inside the cover plate, and all was good.

The motor went in and everything lined up the way I needed it to. Got it bolted down to the saw mounting bracket and everything seemed ready to go.

Here you can see how the front of the adapter plate hangs over the edge a little to get the reach I needed to. As far as I can tell, this hasn’t impacted the functionality of it at all. Everything seems solid. The twin belt pulley installed on the motor and had plenty of adjustment to get it coplanar to the drive pulley.
Things are starting to come together now! While I don’t have any wheels installed on the saw yet, I did give it a test run just to make sure everything was all hooked up and happy that way. It sounded good, and I’m excited to get it up and running for real. There’s still a few more pieces like table, trunnions, and tires. Not quite to the finish line yet, but we’re getting closer!
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