@Aaron: I forgot to mention, yes, the magnets are the Radio Shack variety. Good eye!

@Kevin: Thanks for the heads up! I definitely want to measure RPM in my setup to get a better picture of what's going on. BTW, would you be willing to share some of your insights with the rest of us vis-a-vis improvements you've found? Or has Aaron already laid them all out above?

OK, if this is getting boring just let me know and I'll shuddap. Some more interesting results tonight: It seems that the bearing has a large influence over the performance of this little machine. I built an eight magnet rotor (for the next step--results to be posted in a different thread once it's built ) and the short of it is that it performs better than the six magnet rotor.

Some of the gains are probably due to the fact that the eight was built better than the six; where the six has slightly offset discs in relation to the bearing the eight is almost dead on and where on the six the magnets are attached to the edge slightly non-uniform (one of the magnets is visibly skewed WRT the vertical) on the eight I made sure that they were uniform.

At any rate, when I first put the eight-magnet rotor on it didn't start at all with either 6V or 12V--I thought that maybe the magnet spacing was insufficient. But then I thought that maybe the bearing hadn't loosened up enough (it's the same bearing as on the six-magnet rotor ) and thus broke out the spray lube. Once I did that, it spun up quite well to some fairly high RPM. The current draw was around 120 mA @ 6V.

I then went back to the six-magnet rotor and to my surprise it spun up pretty fast (albeit somewhat slowly) and drew about 90 mA @ 6V. This seemed fishy to me, so once again I reached for the can of spray lube and gave it spritz while it was running. Once I did that, it started going faster while the amps dropped to around 50-60 mA. On subsequent runs, it never got above 50 mA while the RPM seemed to be fairly moderate (no tach yet--!).

So, to sum up, the bearings play a fair sized role in the performance of this machine. The ones I'm using have a fair amount of slop in them--somewhere in the neighborhood of 1-3 degrees from vertical which is bad, bad, bad. You can actually see the six-magnet rotor precess at high RPM. Also, I had to reapply the spray lube to the eight-magnet rotor at least once, as during one run it spun up to the 120 mA point and then a few seconds later lost all power and stopped completely. Good bearings are vital!

On a side note, I was wondering if anyone knows where to get various odds and ends such as spools and bearings. Internet searches tend to lead either to OEMs and industrial suppliers or to wild goose chases. I did manage to find a few sealed pump bearings at the local neighborhood giant home improvement warehouse store. I also found some perfect spools there--too bad they had $7 worth of #18 stranded wire on them. Where is Tinkerer's Depot to be found?