Pop Quiz 2 Update 4

Now that the lathe is better equipped to produce shiny, round objects, it was time to get back to work on Pop Quiz. Having a better tooling stup dramatically improved efficiency, and I was able to complete the motor mechanics today. Now I just await my SDP-SI order for the bearings and some shoulder screws.

Oh, and I also discovered that the lathe does indeed have back gears. They were rather well hidden, but now the operations which need <180 RPM at the spindle can happen

Boring out the 1/4″-walled steel tube to form the motor can, using the not-boring-bar.

A stiff toolpost does wonders for surface finish and accuracy. Here’s the finished can.

Next up was the motor mounting base and the hub for the can. I dug up the micrometer depth stop which helped stop the carriage at a repeatable, set distance. This meant I could manually feed using the carriage handwheel and not the compound slide, which eliminates the risk of accidentally cutting a taper. A DRO would make this unnecessary, but…

The mounting base begins to take shape… The same shape as the first try, but with provisions for mounting two stators stacked on eachother.

After cutting that part off (with a real cutoff blade!), I started working on the can hub. This involved two precarious internal boring operations. The larger one I could take care of using the not-boring-bar, but it couldn’t fit into the 1/4″ starting hole for making the circular bearing pockets (which are only 3/8″ in diameter anyway)

I should have bored these small holes on the milling machine, but instead I took the risk and used a 3/8″ endmill in the tailstock chuck. Oddly enough, it came out way *UNDERSIZED*, at .365 or so. This is weird. Very, very weird. What the deuce?

The three completed pieces after processing. The can presses onto the hub, and is retained by a healthy dabble of green Loctite. The whole thing sits over the mounting base, and a shoulder screw threads through the hub and into the mounting base to keep the whole thing together. I didn’t make the exterior mounting ring as seen in the 3d drawing yet.

Next steps: make the exterior mounting ring thing, as seen in the 3D rendering. Make a fixture for the UHMW slab chassis, then machine it. Get some carbon fiber and make the cover plates. Wait on Banebots and SDP-SI for the load of internal parts.

Now that I have at least part of the machine tools I used the most before, things should go much smoother. Dragon*Con 08 will be here in no time…