Answer from SawStop

[Leon]

"To answer your question: if there is a power failure while the saw is running, the cartridge might stay powered for about 1-2 seconds at most while its internal voltage falls off.

So under those conditions (saw coasting down, no power to saw at all) touching the blade would not activate the safety system."

So here is how I read this. If the lights go out you try not to continue sawing. In the event you are very close to the blade while cutting and the power fails the blade is going to stop more quickly and the brake may activate before the blade stops.

[dpb]

How so????...they just explicitly said "under those conditions... touching the blade would not activate the safety system."

My reading is the sensor electronics may hang on for very short time but again w/o power the likelihood of the fusible link firing is essentially zero.

I'd guess there's also a decent chance the power transient may trash the processor anyway, even if the absolute voltage Vcc hasn't dropped below the Vmin threshold.

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[John Grossbohlin]

Hmmmm..... a product flaw that is ripe for lawsuit picking. In the scenario where the power fails the workman cannot see to control the wood or keep his/her hands clear of the blade and gets badly cut as the saw is winding down. This problem was foreseeable and preventable... One or more large capacitors, or a UPS (uninterruptable power supply) on the safety device could have kept the safety device active for several seconds or more giving the saw time to wind down and the user to safely remove their hands from the danger area. Out lawyer the lawyer? ;~)

John

[Leon]

Power for one to two seconds to trip the brake is enough. I think if you have a black out you are not likely to continue pushing your hand towards the blade and if you do the wood should stop the blade.

Not as safe but a lot of things would have to go wrong besides the lights and power going out.

[Richard]

Why are you pushing your HAND toward the blade in the first place?

I'm going to misquote Wilbur Wright - If you want perfect safety go sit on the fence... (but fasten a seat belt so you don't fall off!)

[G. Ross]

How about those impatient souls who turn off the saw then get cut by the coasting blade as they grab the cut-off piece of wood. Does the safety system remain active for more than two seconds after the saw is turned off?

[dpb]

...

...

I repeat their words...

No power, no trip...

[dpb]

On 12/6/2012 6:06 PM, G. Ross wrote: ...

This isn't turning the saw off; it's loss of power _to_ the saw...totally different.

[tiredofspam]

remember this operates like a GFCI , I don't think it will trash it. There is a chance that the moment b4 power loss, that this might think this is grounded and fire w/remaining voltage. But doubtful.

[Leon]

Well what direction do you push your hand when cutting wood on a TS?

[Leon]

Read his first paragraph. He is just covering his ass in the event that does not work.

[Leon]

Yes the system is active after the motor is turned off and the blade is still spinning.

[Leon]

So do you propose going after the power company? Under normal circumstances the saw safety will work. If the lights go out and the motor looses power I suspect no one will blame the saw should an accident happen.

[dpb]

Read his last words--he said it won't work reliable...which means it doesn't work and isn't intended to work.

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[Ed Pawlowski]

I never push towards the blade. I push towards the back of the saw, usually along the fence or holding a push block. NEVER in line with the blade.

[Leon]

But pushing towards the back of the saw is towards the blade. Not directly but your hand actually comes closer when pushing. That is the point I am making.

[Leon]

Does not work reliably = Does not work. Not in my world.

[dpb]

When the designer/manufacturer says "would not activate the safety system" I think he says exactly what he means. He didn't even say it _might_ work; he said the event which is to be protected against "would not activate the safety system". Can't get more clear than that.

Write him back w/ your "explanation" of how that isn't actually what he said and see what he says in return...

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[Leon]

Actually he did say it "might" work. copied from his reply,

if there is a power failure while the saw is running, the cartridge might stay powered for about 1-2 seconds at most while its internal voltage falls off.

Now granted any time after the 1~2 seconds you would be unprotected from the spinning blade.

Again I read that as the stop might trigger at the moment after the power failure but not after 1~2 seconds.

[John Grossbohlin]

No... poking fun at the flawless product...