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J. Clarke[_2_]

In article ,
says...

On Wed, 13 Oct 2010 23:15:27 -0400, "J. Clarke"
wrote:

In article ,
says...

On Wed, 13 Oct 2010 18:15:40 -0400, "J. Clarke"
wrote:

In article ,
says...

On Tue, 12 Oct 2010 22:25:50 -0400, "J. Clarke"
wrote:

In article ,
says...

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

But would also be totally impractical on a 10" saw.

Why would it be "impractical on a 10" saw? The brake rotors on that car
are IIRC 11.5 inch diameter and the whole brake assembly fits inside a
15" wheel.

You want to put that monstrosity on a tilting arbour saw, mounted
under the saw table and in the path of the saw-dust and have it work
reliably???
Not going to happen - guaranteed.

It works reliably on a tilting Lincoln wheel in the path of rain, road
dust, and whatever else mother nature can throw at it, so why does a
nice, dry saw cabinet present such problems?

Do yourself a favor, pull a wheel off your car and _look_ at the
mechanism.

I've been doing it for over 45 years
I've also rebuilt a few tilting arbour saws - both belt drive, gear
drive, and direct drive..

And yet you see a problem.