UABMM2 Bearings

Getting the bearings fitted in the UABMM2, first we need to turn the 0.500 inch tooling holes into 1.125 inch bearing holes.  The bearing plates are quarter inch thick Aluminum so we can use a Step-Drill, or some people call it a Uni-Bit, to do this.

Some of the steps on the Step Drill are not quite a quarter inch deep so I'll drill out the face as far as I can go, and then finish the hole from the back side.  The advantage to using a Step-Drill is you can make a small pilot hole, right where you want it, and then work it out to the size you need, with out moving the center of the hole.  It makes it easier to keep the center, and minimizes the tolerance errors.

This is the bottom bearing.  These are off the shelf bearings from an Ace Hardware store.  The shaft size is 0.500 inches, and the mounting bore 1.125 inches.  I was working for low cost here, and these bearings were $2.  I could get much better bearings for around $8 from MSC, but I figured that I would try and make it work with the cheaper bearings first, and then I can upgrade later when I need to.

So far I am pleased with the Ace Hardware bearings.  They have a little more play (tolerance) than I like, but they spin good, and that is what really matters.  Now I need to get the Rotor Assembly built.  I need to put a shaft key groove in the shaft to lock the split taper bushing to the shaft.  Then drill some holes in the Rotor to mount the Rotor on the split shaft coupling.  After that I can put the magnets back on to the Rotor and give this another test.