Re: [CAD_CAM_EDM_DRO] Re: Looking for belt drive ISO 10 spindle

flyasuperseven wrote:

>What options are out there for about a 1 hp spindle capable of
>40,000RPM or so? Preferably something relatively affordable for a
>home type machine.
>
>

40,000 RPM bearings are a real problem. You almost certainly need oil
mist cooling. No grease sealed bearing will last more than a few minutes
at 40 K. If you can affort to wait and watch, look on eBay for a Precise
spindle (Precise corp, Precise/Rockwell, and also Westwind). I managed
to snag a Precise/Rockwell pretty cheap on eBay, and it appears to be
in excellent condition. Many of them will run up to 54,000 RPM. The very
early ones used universal motors (brushes) and all you needed was a variac
for speed control. The newer ones (Precise) use 2-phase AC induction
motors.
(The Westwinds use 3-phase, and can be run from a VFD with series
inductors.)
I have managed to spin up the Precise with a Gecko 201A stepper drive.
After all,
a stepper is also a 2-phase motor, although synchronous. But, to get
full speed
and power, you need 2 950 Hz 165 V sine waves at 90 degree phase angles.
So, the Gecko will only get half speed from the Precise. There's a guy
who's been
trying to sell the motor-generator frequency converter for the Precise
spindles
on eBay for years, but it is enormous!

Another scheme, but big and heavy, is a Danly/Onsrud router motor.
These things
are huge, but I think they may go to 40K RPM. I had a 15K RPM model at one
time. I bought it on eBay without realizing how HUGE the darn thing
was! Once it
came in, I realized there was no way to mount it as a secondary spindle
on my
Bridgeport, so I sold it again.

Jon