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Reply to
J. Clarke
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Heck, I think if it was mounted closer to the arbor than the edge, one pad on the arbor side of the blade would be sufficient for a convenience slow/stop.

Reply to
-MIKE-

Maybe so, but that sounds like asking for trouble!

Bill

Reply to
Bill

That very well could be true, and you could also use such a brake with dado blades of any thickness... Interesting observation there Mike; I'm gonna have to go do some peeking inside my Unisaw to see what the possibilities are. :-)

Reply to
Steve Turner

How? Really. :-)

Reply to
-MIKE-

Good. It's about time that happens to someone *else.* Let me know what you come up with so I can take credit for it. :-)

Reply to
-MIKE-

Well, peek I did, but it seems the opportunities for mounting such a device, on the Unisaw at least, are virtually nil. There are just too many clearance problems to overcome. However, it does seem possible that I could mount a thin disc to the motor pulley (one that's a couple of inches larger in diameter) and apply caliper pressure to that instead. The calipers would have to be mounted to a bracket that attaches to the motor housing, but that shouldn't be too hard to accomplish.

Reply to
Steve Turner

I'll defer to your wisdom and experience which is surely more vast than mine. My limited experience and intuition tells me "something is wrong in that picture"... : )

Bill

Reply to
Bill

On the other hand, disc brakes are designed so they don't lock up, this includes the materials used as well plus the modern ABS electronics.

scott

Reply to
Scott Lurndal

A car wheel spinning at 5000RPM's isn't stopped within a single rotation by a caliper disc brake. Why would you expect a saw blade to be?

A car brake is designed to avoid locking up, yet that's exactly the behavior you would want with a sawblade, and you'd want it to lock in much less than a single revolution.

Reply to
Scott Lurndal

A thread getting knocked off the rails here in the Wreck.... imagine my surprise...LOL

Reply to
Robatoy

And here I thought usenet for was for sharing ideas and learning from one another. How silly of me.

Reply to
-MIKE-

Oh the mootness. (NOT aimed at anybody in particular)

Any disc or drum of any size will interfere with the raising of the blade to the point that the disk brake hits the bottom of the table somewhere.

I propose an air bag. Electronically triggered, it throws you backwards across the shop and away from the table saw. Punches you right in the chest with the option for a double bag for some people here in which case the second bag knocks some sense in them. We can glue on a boxing glove for that operation...just a 4 oz. one; you want it to hurt a little. One can mount the boxing glove on an expanding multi-pivot articulated parallelogram. What a stellar idea. I'm talking to investors now. They want to call the company ACME.

Reply to
Robatoy

Beautiful. Wile E. fricken beautiful.

Reply to
-MIKE-

The problem with me sharing something about this is that someone might (conceivably, if they had been drinking, perhaps...) think I know what I'm talking about. I was just thinking about all of the bicycles I've seen that had a brake pad on just one side...

It couldn't be any good for the bearings (on the motor on the TS), huh?

Bill

Reply to
Bill

I read this on the Internet: ... avoid unnecessary stress on the motor or arbor bearings.

Bill

Reply to
Bill

That is a completely irrelevant comparison.

Look at the forces involved. A bicycle brake is dealing with what I might speculate to be 1000x the force.

200lbs at 25+mph is a lot momentum and those little pads do quite a good job at it.

A coasting 10" saw blade along with whatever mass is added to it by the arbor assembly is stopped in a couple seconds by light pressure applied to the side of the blade with a 1cc section of mdf. I do it all the time. I could probably use my finger.

Try stopping a bike going down hill with that little piece of mdf pressed lightly against the wheel. Won't happen. :-)

The arbor on my Delta is a pretty massive item. In another post, I stated that I would put the pad closer to the arbor, *just in case.* However, the arbor bearings that couldn't handle the little amount of pressure it would take to slow down a coasting saw blade wouldn't last very long on a table saw in its normal operation.

Grinding wheel arbors and extensions don't seem to be affected by forces much, much greater than what I've considering.

Reply to
-MIKE-

Now you're reading this on the internet, which also makes it true:

The force applied to the blade near the arbor by a small bicycle brake caliper is going to be far less stressful on the arbor bearings than some gnarly nasty piece of wood that's twisting into the blade at the outer perimeter while you're trying to cut it. When you have a piece of wood that's binding on the blade and you cut power to the motor, think of how little time it actually takes for the blade to stop. What, a second or two maybe? That's all I would be asking for in a convenience brake; to stop the blade within a second or two, rather than the 10 or 15 seconds (or longer on some saws) it takes for the blade to stop by itself, and it's not going to take that much pressure to get it done. And as you've also read on the internet, it's pretty common practice for people to stop the blade by shoving a piece of wood up against it from the side; I'd imagine that would also put more stress on the arbor bearings than an inboard brake caliper.

Reply to
Steve Turner

You NEVER put side loads on a saw blade , particularly when running at speed.

Reply to
clare

If you want to put a friction brake on a saw blade you need to do it on the "non-blade" side of the arbour. Put the brake on the pulley if belt drive, or the "fan end" of the motor if direct drive.

The only problem there is, if you stop the arbour too quickly the arbour nut will wind off as the blade trys to keep spinning. Same thing happens if DC injection on ann AC motor or resistive(regenerative) braking on a DC motor is too harsh..

That's why the "saw stop" HAS to stop the blade directly. Stopping the blade that fast through the arbour would inevitably wind the blade off the arbour before the blade came to a safe stop.

Reply to
clare

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