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Bill[_37_]

-MIKE- wrote:
On 10/13/10 9:43 AM, J. Clarke wrote:
In , says...

J. Clarke wrote:
In , says...

J. Clarke wrote:
In ,
says...

On Mon, 11 Oct 2010 19:59:30 -0400, wrote:

J. Clarke wrote:
In ,
says...

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.

So how much power do you have to put into that electronic brake
to stop
the blade as fast as Sawstop's physical block?

And why would a caliper not last long? A set of brake pads on a
car
with 10" rotors lasts 40,000 miles or so, and they're getting a
Hell of
a lot more of a workout that they would stopping a little bitty
saw
blade that masses less than 1/1000 as much.

The physics on that seem interesting. A little like stopping a
speeding
bullet on a dime--it challenges my imagination. Probably not
quite as
difficult as stopping a lightning bolt, but I wouldn't want to
try that
either.

Bill
No way a caliper could stop the blade in even 4X the time the
saw-stop does. And keeping dust out of the gap between tha "pad" and
the blade would be quite problematic - with dust decreasing the
stopping efficiency by a very large margin.

I suspect that a small pyrotechnic pressurizing one of the
calipers off
my '76 Lincoln might surprise you.

When it snapped (seriously)? I'm not an engineer, so I don't know for
sure. I just wouldn't be surprised. Maybe someone else can opine.

Why would something that can stop a 4000 pound car "snap" when
called on
to stop a 3 pound saw blade?

"Pyrotechnics" rather than a master cylinder with brake fluid?

To stop the saw in a fraction of a revolution, you need rapid
application. A pyro will build pressure rapidly.

I didn't think we were talking about an emergency stop.
AFAIK, we're discussing a convenience stop which, in my opinion, would
be satisfactorily done in a couple seconds, not milliseconds.

I thought we were discussing a stop on the same order as SawStop.
I didn't read every post in the thread.

Bill