Anatomy of a Sawstop brake activation

[Cary Swoveland]

Yesterday I activated the brake on my Sawstop, by sawing into a 22 gauge pin nail. I thought others might be interested in seeing the results.

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As you can see, four teeth of my 40-tooth Forrest blade are embedded in brake's aluminum housing. The one at the left end was the one that hit the pin. (I know that because it stopped short of the left end of the housing.) Notice how the housing is deformed.

Here's a picture of the brake componet's electrical inards.

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When the brake fires, a large current severs a stainless steel wire that keeps the spring under pressure. (I believe the barrel-shaped component is a capacitor.) You can see the severed wire. I don't know how the wire keeps the spring under tensions--perhaps someone can clarify that.

Here's what the blade looked like after removing the brake housing:

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The carbide tip was detached from the second tooth from the right, but the others look OK. Since it's a pricey blade, I'll send it out for repair and sharpening.

I emailed Sawstop to ask if I will need to readjust saw. They said probably not, that it was designed to maintain adjustments after brake activation.

Cary

[Tim Malyszko]

Great post. I'm glad to hear that it was a nail and not a finger that activated the blade, although it sucks having to get the blade fixed and replace the brake. Good to know that it works.

[Joe Chritz]

Were you touching the other side of the nail when you were cutting? I wouldn't think just a nail isolated in wood could make the brake trip but I don't know that much about it.

Joe

[Kurt Bird]

Cary,
I will be really suprised if the blade isn't trashed, but just in case, I suggest you send it back to Forrest with a note about how it happened, and have them check it out. I believe they will be very honest about it, which would calm my concerns if it was mine.
Kurt

[Peter Quinn]

I believe forrest has the capacity to reflatten and balance blade plates, repair gullets and obviously rebraise teeth. Might be worth calling first to confirm that they can restore a blade after a saw stop incedent before incuring shipping charges.

Glad to hear it works, sorry a nail triggered it, glad you weren't injured. I've ripped through pin nails without damage to carbide on accident before. I guess the electronics are pretty sensitive, and now you know it works and wee got to see some pretty cool pics. Thanks for posting them.

[Mark Singer]

Forrest can fix it. It is amazing how quick the SawStop stops. It looks like it only hit 2 or 3 teeth! It stop instantly

[Toney Robertson]

Did you have to change your shorts?

I know I would have! :D

I assume that it makes a god awful racket.

Glad you were not hurt.

Toney

[Greg Funk]

Cary,

Very interesting pictures. I'd be interested in hearing from Sawstop why the brake triggered. I wouldn't think the blade making contact with a nail would set it off unless the nail was touching either you or the saw.

Greg

[Joe Jensen]

I had a cartidge trip. Stupidly, I did not seat the riving knive/guard properly and if fell forward a little and touched the blade with the saw running. My 40 tooth Forrest looked just like yours. 3 teeth hit the stop, one lost a tooth. I sent it to Forrest with a note and they were able to repair and resharpen. Total cost was around $35..joe

[Don Bullock]

Cary, thanks for the pictorial explanation of what happened. It is truly amazing how fast the blade is stopped by the SawStop. I'm glad it was a nail, not your finger.

[Cary Swoveland]

Were you touching the other side of the nail when you were cutting? I wouldn't think just a nail isolated in wood could make the brake trip but I don't know that much about it.

Joe
Good point, Joe. I just checked the Sawstop web site and found a FAQ that said a small nail generally would not activate the brake. I'll mail Sawstop the cartridge. They can download information from it to find out why it fired. (I'll also enclose the part of the board that caused the activation.) If they find it was a false activation, they will replace the cartridge for free. No mention of blade replacement.

Thanks for the observation.

Cary

[Lewis Cobb]

Yep - that big barrel thing is a capacitor and probably is what's used to deliver the large electrical charge that severs the wire like a fuse, triggering the spring. I have never seen the innerds of a cartridge before. Interesting pics.

[Cary Swoveland]

Did you have to change your shorts?

I know I would have! :D

I assume that it makes a god awful racket.

Glad you were not hurt.

Toney

It was not the least bit frightening. One moment you are sawing as usual, then a loud bang, then silence. The silence--signalling any danger has past--comes so quickly that there is no time to be afraid.

Cary

[Cary Swoveland]

Yesterday I activated the brake on my Sawstop, by sawing into a 22 gauge pin nail. I thought others might be interested in seeing the results...

Upon closer examination, I see that it wasn't hitting a nail with the blade that caused the brake to activate. Here's a picture of the approximate position of the blade when the activation occurred:

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and here it is a little closer:

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As you can see, the blade nicked the aluminum fence of my Jessem Mast-R-Slide.

I guess this provides an indication of the damage the blade would have inflicted to my finger, had it been the object that was struck.

Cary

[Dennis Meek]

Carey....thanks for a great post! I have the SawStop and I fortunately haven't activated the brake. I'm very happy that the brake performed it's function for you.

Dennis

[Ben Grunow]

I can attest to the fact that a small nail would not trip the saw as I lost my temper one day and forced my SS to cut 2 drywall screws which removed the carbide teeth from the blade (all of them).

Great post and pics. Dont do what I did. Keep your calm and measure twice.

Ben

[Don Bullock]

Cary,
Thanks for the correction on what caused your SS to trigger. That makes more sense. Since I have an Incra miter gauge I'm going to have to be more careful based on your pictures.

[Joe Chritz]

There ya have it. Looks like it worked just as it was supposed to.

I would still send the cartridge since I am sure they want it for the information it contains. Definitely a DOH! moment. So goes it sometimes.

Joe

[John Gornall]

I found your first picture the most interesting in being able to see the distortion of the aluminium at the top of the picture as it absorbed energy - a lot of clever design in these machines.

[Steven Hardy]

Can you imagine the mess if it was a moulding cutterhead ?

[Guy Germaine]

Just out of curiositie's sake, what does it cost to replace the cartridge?

[Mike Heidrick]

Just out of curiositie's sake, what does it cost to replace the cartridge?

Brake Cartridge for a 10" blade is $69.00.

Moulding cutterheads do not work with a sawstop. You get to use a 10" sawblade and an 8" dado stack.

Sawstop brake fire sounds like a balloon popping, and then the silence. It is kinda crazy to witness. I have not fired my brakes at all but I did see the demo at woodcraft. Crazy.

[Bruce Benjamin]

I can attest to the fact that a small nail would not trip the saw as I lost my temper one day and forced my SS to cut 2 drywall screws which removed the carbide teeth from the blade (all of them).

Great post and pics. Dont do what I did. Keep your calm and measure twice.

Ben

:eek::eek::eek:!!!!!!!!!! Wow! A bad temper and power tools definitely don't mix. I watched a guy get mad and throw his chainsaw out of the tree he was cutting once. At least the saw was off. His boss nearly fired him on the spot. In my opinion he should've been fired. Take it easy.

Bruce