[TCML] Propeller gap V1.0

[Joe Mastroianni <joe@xxxxxxxxxxxxxx>]

Hi All,
I've retired my 4" SRSG and moved on to a larger motor that I had been planning to use to spin an 8" G10 wheel.  I was hoping to experiment with higher break rates, but I got derailed trying to machine my own mandrel, and it seems I'm always waiting for parts from McMaster...meanwhile, it was easy to gen up a propeller gap using a cast bit of G10 that had a 6 5/8" circle cut out of it while I was experimenting with the circle cutting router jig.

<http://yfrog.com/3dphxj>

This gap isn't yet mounted (nor might it ever be - I'm still thinking to go for the larger G10 wheel), but it's just sitting on the power supply bed I built.  There's a piece of 1/2" polycarbonate bolted to the face of the motor, which is hard to see in the pictures because it looks like glass.  The G10 is screwed into some ceramic stand offs that are screwed into the polycarbonate.

I used some copper strip on the back of the G10 to short each pair of electrodes.  This is the stuff you get at the garden shop to keep slugs out of your veggies.  I had to splice 2 strips together, and I found that it does not work weell to simply lay them on top of each other and rely on  the adhesive backing.  I got some nice arcing on my first tries.  I wound up running a bead of solder across the splice to close up any gaps and make a sound electrical connection.

Adjusting the timing is a matter of rotating the polyethelene rectangle with respect to the motor shaft.  I created a tightening arrangement like Gary did, by cutting a slit across the shaft hole, and then drilling and screwing in a tightening bolt.

Getting the timing right was about as mind numbing a process as that of my little 4" disk and 4 rotating tungsten electrodes.  I guess it shouldn't be any different, and it wasn't.  

I was able to use the variac and the capacitor in the Freau phase-shifting arrangement, and that allowed me some "play" in the setting.  However this motor I'm now using is different from the smaller one I had before, so I suspect it doesn't have the same tuning range as the other motor.  I've yet to take any serious measurements, other than to make sure the voltage doesn't spike out of range and drive some awful current through my motor windings.

Performance is, I guess, as you'd expect.  The propeller gap, adequately tuned, with the variac on full power, allows for streamers of about the same intensity as my smaller gap arrangement.  This probably validates the small motor and disk as a usable device - or - serves as an indictment of my lousy craftsmanship...one or the other.

When it gets darker I'll take some pictures of the streamers.  Though I still only have the iPhone to do it with.

Cheers,
Joe

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla