SawStop inadvertent brake activation causes

[D W C 133]

After my first accidental SawStop brake activation - I thought it might be worthwhile to start a thread where forum members can list the causes of accidental SS brake activation - thereby preventing costly and unintentional activation. 

 

As I was setting up my new SawStop cabinet saw, I couldn't help but wonder how long it would take before I activated the brake for the first time - either by contacting the blade with a finger, or a different cause. I arrogantly thought that it would be a long time. 

It took 2 days. 

 

CAUSE: Moisture wicked into plywood. 

I had some plywood stored on 2 stickers to keep it off the floor in my detached garage. Well, despite it being stored off of the concrete, some moisture had wicked up into the workpiece. It was not damp to to the touch at all. There was some discoloration and that was my only clue that it held some water. In reading the manual, it suggests very firmly that a workpiece would have to contain significant moisture to activate the brake. Since there was nothing to suggest that this piece held significant moisture I proceeded with a cut and bam! The brake fired and my brand new SawStop combination blade, and brake cartridge were destroyed. 

While I am chalking this up to a learning curve, I can't help but feel like SS is a little bit accountable here as I was following the manual closely and there was nothing to suggest that I should run it through in bypass mode to determine if the workpiece held enough moisture to trip the brake. In the future, I will be MUCH more likely to test a piece first if I determine there is any possibility of moisture beyond the typical moisture content of kiln-dried hardwoods. 

 

If you have accidentally activated a brake firing from something that you didn't see coming I would love to know about it. I did not see this one coming - but then again it is a brand machine and a brand new safety system that I have zero feel for. Live and learn. 

 

[Mark J 2254]

How are you sure that it was moisture in the plywood?  Did you do some other testing?

[Chet 4938]

2 minutes ago, Mark J said:

How are you sure that it was moisture in the plywood?  Did you do some other testing?

It doesn't take much moisture, the whole system operates around the completion of an electrical circuit.   In fact in the manual they warn against things like pressure treated lumber.  They pretty much recommend overriding there system on pressure treated products.

[..Kev 5868]

I've heard of this happening with glue that isn't fully cured as well because of the moisture.

[drzaius 2635]

I was cutting a board that had graphite cloth glued to it & it set off the brake about 6" into the cut. I didn't see that coming, but I should have. 

Anyway, I'd give the folks at SawStop a call because wood that is not soaking wet is not supposed to trip the safety. Even if you have pressure treated wood that is wet, the manual just says to let it dry out for 24 hrs. Pressure treated would be a worst case because of the chemicals in the wood. To me, that means if it doesn't feel wet, it's OK to go. Of course, when in doubt, test it first to be sure it will cut safely.

[gee-dub 3520]

Mine was from cutting some anti-static UHMW material that I had scrounged from some electronics packaging at work.  Boy, I sure saved money by scrounging that waste material didn't I !?!  The moment I heard the ker-plunk I realized what I had done. Doh!

When you buy a Saw Stop, you buy into the methodology of using one.  If you use it like a tablesaw that does not have the flesh-sensing technology, it could get expensive.  After that learning experience I now use override if I have any question about a false triggering.  If I am making multiple cuts I use override to test the procedure and then run normally -or- in override as the indications dictate.

[woodbutcher 170]

When the saw is in override mode, does it tell you if senses something that would trigger the brake in normal operation?

[Tpt life 2775]

I don’t own a SS but did extensive fire and water damage restoration for a time. Leached salts from prior wet can conduct electricity like moisture, causing some false positives in sensors that rely on conductivity. 

[Chet 4938]

With the saw off but in the regular mode,  if you touch the blade with your finger or a piece of metal or anything else that will trigger the system you will get an indicator light letting you know that that item will activate the system with the saw turned on.  Of course this doesn't do any good if you have an item embedded in the wood that you don't know about.

[wtnhighlander 7685]

@Tpt life probably hit on the real cause, in this case. Water itself is not conductive, but dissolved impurities can be. Likely your plywood didn't hold much moisture, but the moisture did carry some highly-conductive contaminant.

[Chestnut 5647]

1 minute ago, wtnhighlander said:

@Tpt life probably hit on the real cause, in this case. Water itself is not conductive, but dissolved impurities can be. Likely your plywood didn't hold much moisture, but the moisture did carry some highly-conductive contaminant.

Well it has to have impurities because pure water doesn't conduct electricity.

[D W C 133]

2 hours ago, Mark J said:

How are you sure that it was moisture in the plywood?  Did you do some other testing?

@Mark J  I ran it through in bypass and it gave me the code for wet wood.

[D W C 133]

1 hour ago, drzaius said:

Anyway, I'd give the folks at SawStop a call because wood that is not soaking wet is not supposed to trip the safety. 

I submitted an account of what happened via a form on their website. No response yet. I'll update the thread once I do hear back from them.

[Tpt life 2775]

9 minutes ago, Chestnut said:

Well it has to have impurities because pure water doesn't conduct electricity.

Find me some pure water in timber. :-)

[D W C 133]

45 minutes ago, woodbutcher said:

When the saw is in override mode, does it tell you if senses something that would trigger the brake in normal operation?

Yes, it does by flashing a code.

[D W C 133]

1 hour ago, gee-dub said:

 

When you buy a Saw Stop, you buy into the methodology of using one.  If you use it like a tablesaw that does not have the flesh-sensing technology, it could get expensive.  

@gee-dub 

You nailed it. I just learned the hard way that I have to start with a whole new mentality towards using the TS by stronger evaluation of the work piece for potential conductiveness.

I'm just grateful that I had the stock blade on and not one of my "good" blades (mostly Freud's Industrial line). I went to the local big box store and picked up a reasonable quality but lower priced combination blade to use while l acclimate myself to using this new saw. That little mistake cost me about $75 for a cartridge and $35 for a new blade. I can live with that, but if happens again on something that I didn't see coming I might start second guessing my decision to go with SS over other brands that don't have the flesh detection technology.

That's why I started this thread, to increase my knowledge of what can cause the brake to fire.

 

Take care

 

[drzaius 2635]

My lesson cost $200 because it was a good blade & I'm in Canada.

[wtnhighlander 7685]

You can always switch to a treadle-operated table saw. I hear the flesh detection on those is pretty good. 

[pkinneb 3612]

24 minutes ago, wtnhighlander said:

You can always switch to a treadle-operated table saw. I hear the flesh detection on those is pretty good. 

...well at least until your foot falls asleep LOL

[Art 252]

I haven't had an inadvertent activation, but will certainly be following this thread.

Thanks for posting your experiences.

[Bankstick 287]

Good thread and interesting info. FWIW, I would hesitate at buying a SS product.

[JohnG 1206]

Following this thread, as I’m hoping to buy one this year. 

Good to know there is a way to check if it would fire, but I can understand not doing this test before all cuts. 

While an inadvertent Trip is inconvenient and not inexpensive, it is still far preferable to it not tripping when it should.  

[pkinneb 3612]

2 hours ago, Bankstick said:

Good thread and interesting info. FWIW, I would hesitate at buying a SS product.

I have had mine for about 3 years now (I think) and prior to that I had a PM66 (12 years) and a Ridgid (8 years). If you were to bypass the safety feature on every single cut this is still an awesome saw. Awesome dead on fence, unbelievably quiet, best table saw dust collection I have seen, best blade removal mechanism, amazing mobile base, best manual of any tool I have ever purchase bar none. I hope I never need the safety feature but glad its there, when in doubt there are ways to test your material without firing a blade into it. Like with any new tool it takes time to get used to it but the only regret I have is that I didn't go with an industrial unit becuase the table on my PCS is smaller than the PM66 I had prior so that took some getting used to. That's my 60 second review carry on  

[Chestnut 5647]

38 minutes ago, pkinneb said:

I have had mine for about 3 years now (I think) and prior to that I had a PM66 (12 years) and a Ridgid (8 years). If you were to bypass the safety feature on every single cut this is still an awesome saw. Awesome dead on fence, unbelievably quiet, best table saw dust collection I have seen, best blade removal mechanism, amazing mobile base, best manual of any tool I have ever purchase bar none. I hope I never need the safety feature but glad its there, when in doubt there are ways to test your material without firing a blade into it. Like with any new tool it takes time to get used to it but the only regret I have is that I didn't go with an industrial unit becuase the table on my PCS is smaller than the PM66 I had prior so that took some getting used to. That's my 60 second review carry on  

So when are you converting to Mormonism and buying a ring?

[drzaius 2635]

5 hours ago, pkinneb said:

I have had mine for about 3 years now (I think) and prior to that I had a PM66 (12 years) and a Ridgid (8 years). If you were to bypass the safety feature on every single cut this is still an awesome saw. Awesome dead on fence, unbelievably quiet, best table saw dust collection I have seen, best blade removal mechanism, amazing mobile base, best manual of any tool I have ever purchase bar none. I hope I never need the safety feature but glad its there, when in doubt there are ways to test your material without firing a blade into it. Like with any new tool it takes time to get used to it but the only regret I have is that I didn't go with an industrial unit becuase the table on my PCS is smaller than the PM66 I had prior so that took some getting used to. That's my 60 second review carry on  

I agree completely here, even if it makes me sound like a fanboy. The safety brake was at the absolute bottom of my feature list when choosing a new saw.  But the safety features of the saw, because they are so well engineered & easy to use, have made me a much more safety conscious user. And the brake? Well, because I'm cheap & don't want to waste any more cartridges & blades, I always take an extra pause to think before each cut. Flesh will heal, blades & brakes won't