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

The pressure switch on the compressor will try to maintain 120psi in
the tank..  Obviously there's hysteresis to keep the motor from
cycling too often.    That means the tank pressure will increase and
decrease as air is consumed and refilled.

A regulator tries to maintain constant pressure on its output, as the
pressure on the input changes.  Certainly a paint sprayer regulator is
not the most precise device, but I'll bet a decent one keeps the
pressure on the output within 2% of its setpoint..  As long as there's
enough pressure on the input.


Regards,

Matt-

I am still getting an electric motor as I do not have a compressor
in my office :)

The hubs I am having made will work with a 1/4 inch die grinder.

BTW Mark, I think two RX8 wheels back to back will put
out a stronger CAS signal. I think Mazda got a bit carried
away saving weight.

Paul Lamar