10" Saw Blades

[Jim Behning]

Well think of it as an uninsulated screwdriver, pliers, crimping tools etc. Electricians do not tend to use uninsulated tools and an uninsulated tool is just an extension of their hand. An electrician blew himself up two weekends ago in our office complex. His helper got

60% burns. The how is with the lead electrician. They were having some issue with the building popping main breakers. Electricity scares me.

[DerbyDad03]

The only time I saw the SS being tested was on TOH. The words "senses the moisture in your finger" were used to explain the firing mechanism. They laid a hot dog on top of a piece of wood to fire the brake.

The moisture statement didn't sit well with me since wood can have varying moisture levels, even within the same piece of stock, so how would it know the difference between an uncut finger and a piece of wood? The fact that it fired with an allen wrench also tells me that moisture isn't involved.

So, how does it work?

[Leon]

This is what was originally said,

He saw the manual and thought the idea of a saw stopping mechanism was just too cool, so he fired up the saw and touched the spinning blade with an "alan" wrench.

[Nova]

Quoted from an article on SawStop's web site:

"The braking system works by applying a minimal voltage (too low to feel) to the arbor and blade, which are isolated from the rest of the saw by a high-impact nonmetallic arbor coating. If you touch the blade, your body draws off some current, thus lowering the voltage. The saw?s electronics sense the change in voltage and trigger the brake. The torque created by the rapidly stopping blade subsequently causes it to drop below the table surface. All of this takes place in the time it takes three to four blade teeth to rotate through the contact point."

[Glen]

Yes. I may not be explaining it scientifically correct, but if something touches the blade while on or still spinning the brake mechanism will trip. It has something to do with changing the current flow through the blade. (You scientific type people, feel free to interject with a more clear explanation, if you like) The manual warns you that wood with a high moisture content could cause a false firing. The positive side is that you can touch the wood to the blade while off and a light will signal if it would trip the brake mechanism, and you can turn off the brake with a key. We have been using the saw for about a year now, and that was the only time the brake fired. May I add, I really like the saw. It not only passes the nickel test, it passes the dime test.

Glen

[bridgerfafc]

no, that's proper function for that machine.

[bridgerfafc]

something that conducts electricity very much better than dry wood, that is.

[Glen]

That would be a yes.

Glen