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Re: RSG Treadmill Motor

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Steve, all,

I, too am in love with treadmill type DC motors for ASRSG drive
purposes ;^) Mine that I am using in my large coil that I am in the
process of building is a 2.5 HP, 130 VDC, 3500 RPM motor. It
cost me considerably more than $10 but then again, it's a little fan-
cier than this one, too :^) The motor body is over 11" long and
has a built-on mounting foot. There is also no perceptable end
play on the shaft of mine and the biggest problem was getting the
GPO-3 disc balanced and the electrodes positioned properly
(and perpendicullar) along the same axial position of the disc.
Actually, I didn't get them quite prefect, but was able to get
them pretty close. Darn, it's hard to machine nice looking stuff
w/out a lathe and a drill press, minimum. I did end up finding
a local fellow hobbiest who had a nice acoutrement of machine
shop tools in his garage and I got him to put a few of the finishing
touches on my gap. I should have let him do all of the drilling from
the beginning and that would've saved me a lot of headache and
I would have ended up with a "perfect" looking RSG ;^) But
all in all, it's definitely the best and nicest looking ASRSG that I
have built to date (not that that's saying much) ;^)

BTW, 1000 uFd seems kind of "overkill" on the fitering to me.
I use 200 uFd and it seems to work fine for me. I get similar
current readings on mine with the 200 uFd cap for filtering.

David Rieben

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, January 01, 2005 12:25 PM
Subject: RSG Treadmill Motor

> Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx> > > Happy New Year, > > For those contemplating building an asynchronous rotary spark gap, the > following may be useful: > > I bought one of the new $10 surplus treadmill motors from Surplus Center > (www.surpluscenter.com), Item # 10-2167, and I am most pleased with it. It > is a permanent magnet DC motor rated at 2.25 HP at 260 volts and 5 amps. > The bearings are tight with inperceptable end play. It comes with a 6 inch > diameter combination flywheel, cooling impeller and pulley that is perfectly > balanced. The temptation to use it as-is as an arbor for the RSG rotor was > too much, so that is what I am using. As there are 11 impeller blades, I > had to drill 11 mounting holes between the blades through the rim to attach > the rotor. Any other number of bolts would result in imbalance. > > With the hub at 6 inches, the rotor must be 12 inches in diameter to allow > enough space between the electrodes (mounted at 11 inch diameter) and the > "arbor" rim. This is not a problem - there is power to spare to turn this > relatively large rotor, a 12 inch x 3/8 inch piece of GP03 (electrical grade > fiberglass) from McMaster Carr (8549 K47), cost about $13. > > A small 0 - 120 VAC variac powers a full wave bridge rectifier with a 1,000 > uF filter capacitor. Here are some test results: > > Rotor RPM AC Volts AC Amps > 1000 30 0.6 > 2000 56 1.1 > 3000 82 1.9 > 4000 106 2.8 > > At 4,000 RPM, the motor power needed is only about 0.4 HP, and it runs cold > and is very quiet. I will be using 12 rotor electrodes, so at 4000 RPM, the > break rate will be 800 which is more than adequate for most purposes. > > Bottom line - this is a winning combination, and I commend it to anyone. > > --Steve Y. > > >