Mark, I have an extra RX8 trigger wheel
  and my next door hangar neighbor is making a hub
  for it as we speak.

  http://skycraftsurplus.com/dcmotorhighrpm.aspx

  I will try to find a better motor as the shaft
  diameter on that one is a bit marginal IMHO.

  Paul Lamar

  Paul,

 How about using an air grinder?

 Mark

 That would work. I checked mine and it goes to 22,000 RPM.
 The question is.... how do you control the speed?

 Paul Lamar



Hi Paul,

Use a pressure regulator and slowly bring the pressure up until you get the
RPM you want. Check with an optical tach.

Dale Davies

The trouble with that is the air pressure regulator on most compressors
are not proportional. It is what we call in the servo biz; bang bang.
Too high turn it off. Wait. Too low turn it on and wait.
Right amount turn it off. Repeat. So the RPM is cycling up and
down. Which may still work for our purposes but not ideal.


Paul Lamar

Paul,  To do speed control on pneumatic or hydraulic motors you need to
meter the volume not the pressure.  This is done with a flow control which
does not cycle on and off,  such as a needle valve.  Additionally the flow
control needs to be on the exhaust  port of the motor to control the speed.
This will provide full torque capacity of the motor. The torque is
controlled by the inlet pressure which in this case would be fixed at the
tank pressure of your shop air. Set the tank pressure a little under the
rated pressure of the motor and don't use a line regulator. If you use a
line regulator it will need a 100 foot hose for an accumulator to dampen
pressure pulses from the regulator.

george grimes