Sawstop Brake Fired (Update)

[alex grams]

As an update to This thread about my brake firing (http://www.sawmillcreek.org/showthread.php?174216-Sawstop-brake-fired&highlight) I got a response from the brake cartridge analysis sent in to Sawstop.

They said that it was shorting out no something metal (Riving knife/Brake Cartridge/?), however the riving knife was off as I was making a dado crosscut with my miter gauge and I have to remove the riving knife as it protrudes higher than the blade depth of cut, and they said the brake cartridge gap was set properly, but this really leaves me at a loss as to what caused it.

The other option was that the blade hit the mitre gauge, but I wasn't even 1/3 of the way across the cut when the brake fired, so physically I wasn't anywhere close to the gauge, (that is assuming also that I set it in the wrong miter slot, which wasn't the case).

I am really at a loss. I don't want to run a $100 blade on my tablesaw + a $60 brake on the chance it could happen again, at a minimum costing me $70 (new brake + sharpening/blade tooth weld check).

The sawstop tech, while nice and courteous, was also at a loss on suggestions, and really didn't offer a follow-up or any more suggestions. The conversation basically ended on the note of 'tough luck. We can't really tell what happened, just run it again and we will see what happens' and if it fires again let us know'.

I don't find it acceptable to run the equipment in safety mode bypass as a normal function, nor do I want to stick more money back into the unit at a risk of damage with no explanation as to the cause of the firing.

Anyone have any suggestions? I cannot think of anything else to check, nor could the Sawstop Tech.

I have always been more than happy with SS customer support, but this lack of a cause of firing and the open ended/undiagnosed problem really is souring me.

I know how sawstop threads go, so please keep this subject oriented. I just want help finding a way to address this and prevent it from firing again. This is not an invitation to discuss the merits/costs/fandom/anti-fandom of Sawstop.

[Prashun Patel]

Alex-
I would trust the diagnostics for now. Better that it fires too often than not enough!!! I think if it misfires enough times, Sawstop will do the right thing. I'm inclined to trust their conclusion.

As far as the riving knife - I had the same problem. The easiest fix is to grind down an mm or 2 off the top of yr knife. You can use the bench grinder or an angle grinder for this. It does not diminish the safety of the knife at all. It was the SS tech who recommended I do that. It has worked wonderfully.

[alex grams]

Just stinks to not have an answer and lose $70 and have to buy another cartridge.

I did come across your grinding solution in another thread while researching some on this issue. I will do that this weekend. I always hated having to remove that for a quick dado on a board.

[Prashun Patel]

"quick dado" and "Sawstop" don't belong in the same sentence. Since Sawstop, I've been 'dadoing' with a 1/8" thick combination blade, nibbling the cut, and then cleaning with a shoulder plane.

[alex grams]

I dont have a 1/4" shoulder plane..... I should put that on the list!

[Paul Wunder]

Alex,

I do not own a SS, but who knows, I may someday. Just curious as to whether the analysis and explanation was based on a single "tech support" person's analysis or was there a pursuit for an answer high up the management chain. I have often gotten satisfaction in other companies by escalation but I do not know if that is necessary at Saw Stop.

Thanks, Paul

[mreza Salav]

Have you checked your dado blade to see if it is missing a tip or something (coming loose and shortening the circuit?).

I am dealing with their CS on a different matter right now and I'm surprised (for the 2nd time) by how far they go to satisfy the customer (my saw is 2 years out of warranty and it doesn't have a "real" problem just something I wasn't very happy with and asked them how to fix it but they are making it right, way beyond what I expected).
I have found that their tech support are very well trained and well informed. It might very well be a metal contact somewhere.
I would try to rule out the obvious ones and don't worry about the next brake fire.

[Peter Aeschliman]

I've never really understood the benefit of sending the unit in to them. Barring a massive failure, I don't know what they're going to tell you. They're going to say you must've hit something conductive. I don't think they'll ever admit there was an accidental firing because there's no way for them to make that determination with the data they have (again, assuming that there wasn't a massive, obvious failure in the circuitry).

Anyway, I'm sorry you're having issues man. Have you used the saw since the brake fired? Do you have a cheapo blade you can use with it for a while until you get more confident that it's okay?

[Allen Breinig]

Is it possible that these "misfires" are being caused by a static electrical buildup caused by the sawdust swirling inside the cabinet or moving into the dust collector? Are these saws being grounded anywhere to prevent a static electric buildup?

[Kyle Iwamoto]

While I have not had a misfire yet, the benefit for sending the brake in, is they supposed to send you a replacement. And the research they gain from the cartridge. Maybe in the future, with the data coming in, they very well may be able to figure out what is causing the misfires and correct it. I'll take a misfire any day, as long as it does fire when I need it to. Well, as long as it doesn't misfire a lot......

Thanks for the update. Oh, grinding down the riving knife works. Easy to do too.

[Andy Sowers]

My understanding is that they only provide replacement brakes when flesh is involved... that's where I think they are continually trying to improve the "algorithm/firmware." But since I've never had a false break incident, I cannot speak from experience...

Andy

[mreza Salav]

They can analyze the data to reduce the number of false positive (mis-fires). I have heard/seen they send a cartridge if they find out it should have not fired (for whatever reason).
As mentioned earlier, its better to have false positives (mis-fires) than false negative (not firing when it should). Of course you should find that right balance and that's why they need
these data to analyze.

Based on what I have learned (after talking to the tech guys) they have improved their technology since the first batch of saws (components have changed as well as how things were designed), although many users (including me) were not aware of these changes. One of the few manufacturers that is not producing the same saw after many years without any new innovations.

[Matt Cook]

I purchased a saw stop after a table saw injury. I am very experienced with heavy machinery but mistakes happen. Though this may not make you feel better, I think you should know that technology can only do so much and it is rarely perfect. Most large production equipment have multiple safeties and in many cases, even multiple safeties don't prevent injuries from happening. I don't recall ever hearing of an equipment owner being upset a safety fired unexpectedly but that may be because each time it did, it didn't hit directly into their pocket book. Our machines (the Sawstops) only have a single safety in place. It's trigger is static electricity which, IMO, isn't exactly the most accurate. I would guess though, that before the SS was released to the public, it was determined that the downside to the technology used wasn't a safety concern, it was a money maker 'cause you're gonna need a module. If you listen you can probably still hear the echo of the chuckling. Misfires won't be a statistic they'll track but they will let you know it can happen so you can't be that pissed. Tech support can't tell you it won't happen again and they can't tell you why. In your case it was moisture, to much iron in your diet, the wood itself, or some other wild guess but, if they could be completely honest, they don't know why and have been given a play book to help get you around the question and back to work. It could have been a failure or legit but there's no log file they can open to tell them why.

So, I think us Sawstop owners have to get that we paid a lot of money in the hopes it does work when we need it to and that module failures don't wipe us out before then. I've had one misfire, like you, that couldn't be explained. Sadly I wasn't totally paying attention to the situation like you were and I couldn't even begin to explain the details. What I can tell you is, at that moment in time and every minute there after, I still had 10 and that's why I coughed up the big bucks in the first place. My Jet Cabinet saw is every bit of the machine the SS, half as expensive, far easier to setup, and has less working parts. What the Jet can't do is help if I have an accident. My first and only equipment accident was with the Jet and it cost thousands. It would take a misfire every month for two years to come even close to comparing to the doctor bills.

Again, I'm lucky and still have 10 fingers. What's one or more worth to you? The Sawstop company is counting on you paying to keep all 10. Now if your saw stop fails to fire...that's a completely different argument. I'll settle for erroring on the side of caution.

[Mark Engel]

If you don't want to chance ruining a $100.00 blade, then don't. Go to any BORG and buy a cheap blade and try the cut again.

The only way to find out what happened is if it happens again, and you keep track of everything you were doing at the time. Sounds like a lot of work.

[Larry Frank]

I think that the technology actually is measuring inductance in the system and not static electricity. I knew when I bought mine that there were risks of a false firing of the cartridge or one that fires and I will not know why. I would think they would tend to risk a false fire rather than a non-fire when it is supposed to. Will I be unhappy if I have a false fire - of course. The possibility of that happening is part of owning one and I accept that. If it happens a couple of times, I will be very unhappy.


I copied this from the website and there is more if you google sawstop and inductance.




"The SawStop safety system includes an electronic detection system that detects when a person contacts theblade. The system induces an electrical signal onto the blade and then monitors that signal for changes. Usinga digital signal processor to constantly monitor the saw, it’s a smart saw, ready to react if an accident occurs.The human body has a relatively large inherent electrical capacitance and conductivity which cause the signalto drop when a person contacts the blade. Wood has a relatively small inherent capacitance and conductivityand does not cause the signal to drop."

[JohnT Fitzgerald]

I was cutting a lot of PVC (Azek) on my SS at one point, and I contacted SS Customer Service about that very issue. I was told that static buildup should not be a problem.

[Matt Cook]

I think that the technology actually is measuring inductance in the system and not static electricity. Yep, I used the wrong words. I didn't mean static but it came out anyway.

[Dan Hintz]

"The SawStop safety system includes an electronic detection system that detects when a person contacts theblade. The system induces an electrical signal onto the blade and then monitors that signal for changes. Usinga digital signal processor to constantly monitor the saw, it’s a smart saw, ready to react if an accident occurs.The human body has a relatively large inherent electrical capacitance and conductivity which cause the signalto drop when a person contacts the blade. Wood has a relatively small inherent capacitance and conductivityand does not cause the signal to drop."
Right there in the text.. capacitance, not inductance. :)

[Neil Brooks]

Still more techie info about the SS.....

http://machinedesign.com/article/capacitance-system-stops-table-saws-from-amputating-fingers-0420

[Mike Heidrick]

Dont forget too - when the saw system (not spinning) is on and the light is green it is still checking for error. Mount your blade, turn the system on (again not spinning) and roatate the blade with a piece of wood. If it stays green and does not flash it would not fire. You can check out your blade without risking a misfire.

I know I would be cleaning my saw out before running it again just to make sure there was no metal somewhere too. At least a good air compressor blow out while my DC was running to clean it up a bit. Then again do the test above.

Putting your finger on the non spinning blade with the system armed will cause teh light to flash alerting you that it would fire the brake if the blade was spinning. Do that too to make sure everything is working OK.

[Steve Jenkins]

What were you cutting when it happened?. If it was ply,mdf,or particle board I have found scrap metal in all three at one time or another. the worst was a 3/8 x 1" bolt in a piece of 1" mdf. I know there are all kinds of things to make sure that doesn't happen in the manufacturing process but .

[Matt Cook]

I have found a 3/8 x 1" bolt in a piece of 1" mdf...

Uh...WHAT?!! If I "came across" a bolt of any size while cutting on the table saw it would take me half an hour to recover from the shock. Makes sense that it's possible but still...

[Don Bullock]

I purchased a saw stop after a table saw injury. I am very experienced with heavy machinery but mistakes happen. Though this may not make you feel better, I think you should know that technology can only do so much and it is rarely perfect. Most large production equipment have multiple safeties and in many cases, even multiple safeties don't prevent injuries from happening. I don't recall ever hearing of an equipment owner being upset a safety fired unexpectedly but that may be because each time it did, it didn't hit directly into their pocket book. Our machines (the Sawstops) only have a single safety in place. It's trigger is static electricity which, IMO, isn't exactly the most accurate. I would guess though, that before the SS was released to the public, it was determined that the downside to the technology used wasn't a safety concern, it was a money maker 'cause you're gonna need a module. If you listen you can probably still hear the echo of the chuckling. Misfires won't be a statistic they'll track but they will let you know it can happen so you can't be that pissed. Tech support can't tell you it won't happen again and they can't tell you why. In your case it was moisture, to much iron in your diet, the wood itself, or some other wild guess but, if they could be completely honest, they don't know why and have been given a play book to help get you around the question and back to work. It could have been a failure or legit but there's no log file they can open to tell them why.

So, I think us Sawstop owners have to get that we paid a lot of money in the hopes it does work when we need it to and that module failures don't wipe us out before then. I've had one misfire, like you, that couldn't be explained. Sadly I wasn't totally paying attention to the situation like you were and I couldn't even begin to explain the details. What I can tell you is, at that moment in time and every minute there after, I still had 10 and that's why I coughed up the big bucks in the first place. My Jet Cabinet saw is every bit of the machine the SS, half as expensive, far easier to setup, and has less working parts. What the Jet can't do is help if I have an accident. My first and only equipment accident was with the Jet and it cost thousands. It would take a misfire every month for two years to come even close to comparing to the doctor bills.

Again, I'm lucky and still have 10 fingers. What's one or more worth to you? The Sawstop company is counting on you paying to keep all 10. Now if your saw stop fails to fire...that's a completely different argument. I'll settle for erroring on the side of caution.

Very well said Matt. I'm sorry to read about your accident, but fully agree with your assessment of the SS safety features. While I've never had an accident with a table saw I have a SS for that very reason.