Reply by oldnovice

Back EMF is more of a factor in DC motors and it has little if any effect on keeping the motor turning as that is due to the physical size of the rotor. And, physical size of the rotor has a lot to do with the amount of HP that a motor can develop.

I once worked with a motor that had a hollow rotor core and because of that it could start, reach 10,000 RPM, and stop at a 1KHz rate. On a servo system these motors could stop almost instantly due to the braking provided by the servo system! The problem is that to get a motor/servo system with enough HP to run a TS would be expensive.

Perhaps a hybrid of the hollow core and HP is a possible solution!

A blade clutch could be a solution if the blade also had a brake. If the blade was cutting stock the resistance of that would be a near instant stop but is would depend a lot on the material being cut so a brake would be desirable to have a consistent stopping time.

There are still some problems with the clutch/brake system:

1. A rotating clutch/brake would increase the inertia.
2. In order to get the required response time out of these magnetic components they must either be very small or highly over driven, possibly to near the destruction point of these components, and small components may not be up to the task.

I hope that I am not being too much of a wet blanket; let me know when to stop!

-- "I never met a board I didn't like!"