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



Paul,
Here's another option... Use a wood router with an aftermarket speed
control.  I bought a $20 speed control unit from Harbor Freight.  But if you
don't have a router, this might be an expensive solution.

Mark

That sounds pretty good. I have a router and Harbor Freight
is close by.

Anheim Motors has not called me back so I am going to look in
McMaster Carr cat.

I have got to go out to the hangar and see how Jim is doing
on the RX8 hubs. I'll sell you one if you want it. Jim is making
two.

Paul Lamar

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