Hub Caps

The next job was to machine the polycarbonate hubcaps.

The first step was to cut out a somewhat circular shape on the bandsaw. Then I center drilled it and and put it in the lathe for pressure turning. Pressure turning is when you use a centering bit/cone and press the workpiece against the chuck:

Doing this allowed me to round the edge and get a precise diameter.

 

Note the scratches from the chuck teeth- I didn't have enough pressure on them.

The next step was to take it out of the lathe, change the chuck, and grasp the outer circumference so that I could bore out the bearing surface. It turns out that I needed to take off about 8 thousandths less than the bearing OD for a nice fit. That seems like a lot, but polycarb is significantly softer than metal.

The four outer hubcaps.

Next, I needed to do the inner side hubcaps. These required a 2in bearing surface hole all the way through. So the first thing I did was take a 1.75" hole saw to them:

The hole saw was a pain because of the massive amount of friction it made and the tiny amount of surface area I could clamp (all of them spun in the clamps at least once). Then I put them on the lathe and cleaned up the inner surface.

Next came mill work. I needed to bore 10 holes (5 for an alignment pin and 5 for 4-40 screws) and cut a 3/32" o-ring groove. EZ-Trak to the rescue:

 

Note the ultra-thin parallels.

It worked pretty well.

ooo...Shiny

 All that's left for these is cutting the 1/16" polycarb endplates for the inner-side hubcaps and threading the 4-40 holes. 

All that's left to do for a test motor is: 

1. The above

2. laser cutting acrylic spacers and hall-effect board

3. winding a stator

4. cutting alignment pins

5. gluing magnets

6. assembling

Oh and: 

soldering lots of surface mount stuff on two S-Electronics 3PH Duo's. Oh boy.