RE: RSG Treadmill Motor

[Tesla list <tesla@xxxxxxxxxx>]

Original poster: "david baehr" <dfb25@xxxxxxxxxxx>


do you have pics of your gap ? , sounds good. My first rotary gap motor was 
an ol' standard 12v auto heater blower motor. I'd pump 24v or more into it 
to get the speed up, it got hot. but never gave out. There was some end 
play in it, but I worked around it........keep sparkin'!!!!

 >From: "Tesla list" <tesla@xxxxxxxxxx>
 >To: tesla@xxxxxxxxxx
 >Subject: RSG Treadmill Motor
 >Date: Sat, 01 Jan 2005 11:25:43 -0700
 >
 >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.
 >
 >