I saw a guy use a brushless outrunner and an ESC to make a hobby CNC spindle drive. I looked like it worked but would it be possible to use an ESC with a governor that would maintain a certain RPM under load, like a helicopter?

I think the answer is yes, but can the RPM be set by the throttle position? Instead of having it "pre-set" to a certain RPM. I'm not familiar with using a governor on an ESC.

Should work, as long as it's powerful enough for whatever you're cutting or whatever. What do you plan to use for a power source?

As I understand it the RPM is set by the governor. But some have multiple settings for different flying modes, that may help. Aerospire is one.

Probably just cutting wood and plastic, 1/4", 5/16" or max 3/8" cutter. 5-20k RPM or so.

Power supply could be anything. 24-50 volts. I've been using a sweet little variac and rectifier (and big cap) to supply 10-12 amps at 40 volts to the stepper board.

I just tried playing with the CC ICE 80HV I have, it has 3 different RPM setting, and some other modes I don't quite get. By loading down the outrunner with my hand I can tell that it does slow down a bit, but it does increase the power to keep up. But when it goes from load to no load it really over shoots the RPM before it can reduce power.

Seems like it might work, maybe more playing with settings would get it better, or maybe Castle could come out with "spindle drive" firmware!

Here's the guy that gave me the idea:

http://garageshopconfessions.com/?page_id=69

Interesting features, never looked at the Castle flying stuff much. Do you have the Castle Link? Check out the Governor Low and Governor High settings on the throttle tab, appears to do exactly what you want!

Phoenix Ice - Heli Programming Screenshot

Snip from the beginning of the last page of the online manual:
For maintaining the speed as load goes off and on, try adjusting the Governor Gain, I expect up. I assume this is for adjusting the Proportional gain of the servo feedback loop, the first step in tuning a servo drive. Don’t try too much at once, too much gain makes the system unstable, although they may not give you that much control.

I don’t see the typical Derivative or Integral (aka Reset) functions of a common PID control loop, but if you do run across those I might be able to help more.

High voltage, good move, that will help with power.

Hmmm...I may try a little variable speed router. Wouldn't be able to control the speed from the program, but...

One I was looking at said it "load compensates" to try to hold the RPM. Might be simpler than trying to reinvent the wheel.