Motor Reversing

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.

Reply to
clare
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Another important part of the SawStop design is that the blade is dropped below the table's surface as the blade is being stopped.

Reply to
Dan Coby

"electromagnet/solenoid would do the trick"

My God man, you've invented the Saw Stop!

Reply to
Hoosierpopi

wildly advancing your fingers towards the blade,

As is done when, say, you are pushing a bit of wood into the saw and it jerks out of place and you essentially "fall" forward now that the wood is no longer offering resistance?

Of course, the blade never stop turning at all on the saw I was using, but I did manage to put three finges and a thumb in its path before realizing I was cutting skin and bone - and jerked back.

Only cut clean through one digit and got it sewed and screwed back on.

Reply to
Hoosierpopi

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

Reply to
J. Clarke

Hardly. There's a lot more more going on with that thing than a simple current running through a magnet.

Reply to
-MIKE-

I've read that about five times and have tried to visualize what you're talking about, but I'm still puzzled.

Would I be correct in assuming you were pushing the wood into the blade with your bare hands rather than using a push jig or Gripper or something similar?

Reply to
Steve Turner

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.

Bill

Reply to
Bill

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

Reply to
J. Clarke

Yes but the heat will do what to the saw blade?

Mark

Reply to
Markem

About the same thing it does to a brake rotor I suspect, polish the sides a little bit.

Reply to
J. Clarke

I doubt most people use a pusher stick to cut plywood sheets.

Now we have to define "close"...LOL

I've read that about five times and have tried to visualize what you're talking about, but I'm still puzzled.

Reply to
Josepi

General rule is don't have your hands in in line with the blade, or within 4 inches of it in any direction.

Reply to
J. Clarke

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

Bill

Reply to
Bill

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

Reply to
J. Clarke

First of all, he never said what kind of wood he was cutting, but from what he

*did* say I kinda doubt it was a sheet of plywood. Secondly, I said push "jig", not push "stick", and I meant one of these:

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course, right there in the description they're calling it a push "stick", which I think is erroneous. When I hear "push stick", I think of one of these pieces of crap:

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I would *never* use; they give me the willies. For plywood, it's entirely plausible to use a "push block"

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it's a really big sheet of plywood, I use these whenever I can on larger panels to keep them against the fence and my hands away from the blade. I use a GRR-Ripper for almost everything else that requires close proximity to the blade.

Reply to
Steve Turner

Uneven heating of a metal disc also would cause it to warp. But then again the "cartridge" in a Sawstop is toast when activated.

The two times I trimmed my finger nails with a tablesaw was it was a Delta TS220 I had at the time, I was in a hurry impatient a bit tired, which equalled being stupid.

The Unisaw which I have now seems safer, and that is more than a reason to be careful.

Mark

Reply to
Markem

That is what I what I might expect to increase the probability of failure.

Given blade radius and density, and rpm, you could probably integrate to compute the (foot-pounds of) energy that need to be stopped in a small fraction of a second (I hope that the dust on the blade won't be an issue). :) I've seen you post in another "forum" so I believe you are up to the calculation. I do not have engineering background to back me up, I'm just thinking it through with you and everyone else who is reading. Evidently, you'll need to generate the equivalent of an equal and opposite amount of energy. This means, I think, that you only get the benefit of a "projection" (dot product) and not all of the force you can apply to the side of the blade. My reasoning could definitely be off, maybe a physicist or engineer could help out?

Regards, Bill

Reply to
Bill

Think about what would happen if you were walking with a cane, and the tip of the cane slipped on some ice. It's analogous.

Bill

Reply to
Bill

Nothing. A lot more heat is generated by cutting than would be generated in the half second it would take to slow down the blade.

You guys do realize we're not leaving the motor on in this scenario, right? :-)

Reply to
-MIKE-

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