I would think that an emergency stop mechanism would be a whole different
magnitude than a scheduled, everyday, stop.

For a finger saver an emergency stop mechanism would have to stop the blade
in a few teeth passings. For everyday usage a couple dozen blade rotations
would be OK too. These two situations would require different tactics.

A dynamic electronic brake could vary the intensity for the two different
scenarios and we could add the caliper to the emerg stop. A caliper probably
wouldn't last long in everyday usage and would need to be adjusted and/or
replaced frequently.


"-MIKE-" wrote in message
...
I would prefer powered off/normal on, because the operator would get
used to the blade always braking and in the case of a solenoid failure,
the blade would not coast.

I would also think an assembly with wheels applying just a little
pressure to the sides of the blade would make a decent passive system.
It would be just enough pressure to slow down the blade in a second or
two and not enough pressure for the motor to even register the resistance.

Think about how little pressure it takes with a scrap piece of wood to
stop a coasting blade.

--

On 10/10/10 10:34 PM, Josepi wrote:
For fast stops a powered brake on may be preferred to normally brake on
with
a spring setting the speed and strength to be held open all the time.