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Forum topic by jklingel posted 11-13-2016 08:13 PM 1059 views 0 times favorited 21 replies Add to Favorites Watch
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jklingel

63 posts in 997 days


11-13-2016 08:13 PM

... at least on rigid foam. I never thought about the gasses and crud coming off rigid foam setting off my SawStop, but it sure did. I was going to cut the foam so we could squeeze it in between rafters, and got about 1’, then POW. Thankfully, I had an extra cartridge and was able to knock the blade out of the used cartridge pretty easily. I was pleasantly surprised at how easy it was to install a new cartridge, too. So, no more foam on the saw table. Maybe SawStop can add foam to their “do not do this at home” list…. ?? Cheers. john


21 replies so far

View Dan's profile

Dan

645 posts in 1732 days


#1 posted 11-13-2016 09:35 PM

Just use bypass mode. Is your blade still usable?

-- Peace on Earth

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Kazooman

871 posts in 1793 days


#2 posted 11-13-2016 10:14 PM

Just curious for more details on the rigid foam. This wasn’t the type with a foil surface, was it? That would certainly do it.

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bigJohninvegas

384 posts in 1302 days


#3 posted 11-13-2016 10:28 PM

You got lucky on saving the blade. While I have never been at the conrtols when a brake trips, I have been in the room a couple times. scratch a woodworker 2 blade and cartridge. Saved the finger though.
Interesting with the foam. Static electricity maybe. Your body conducts electricity and that is how the system detects flesh. I knew metal would do it, anything that is electrically conductive. DanielP is right, make sure you use the bypass next time.

-- John

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AHuxley

652 posts in 3162 days


#4 posted 11-13-2016 11:07 PM


Your body conducts electricity and that is how the system detects flesh. I knew metal would do it, anything that is electrically conductive. DanielP is right, make sure you use the bypass next time.

- bigJohninvegas

Actually, the system works on capacitance not conductance. While there needs to be conductance in order for the system to determine the capacitance it does not fire because a conductor touches the blade but fires because what touches it is conductive and ADDS capacitance (ability to hold electrons) to the system. If it fired based on conductance for something to fire the system a circuit would need to be completed.

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clin

754 posts in 836 days


#5 posted 11-13-2016 11:47 PM

I’d be concerned about reusing that saw blade. It’s possible a tooth or two has been damaged and could come flying off.

I know I’ve cut foam on my saw before. I put it in bypass mode due to rumors about triggers, but I’m sure it didn’t detect it. I doubt there is anything about gasses or crud (whatever that is) being the issue. Static electricity seems like a possibility.

Rigid foam is an insulator, but being a good insulator means surfaces charges do not dissipate easily and are easy to build up. As we all see when those little bits of foam cling to everything.

Whether there is already charge built up on the foam, or somehow the moving saw blade, or even airflow from dust collection causing a build up, I just don’t know.

Seems like this is probably one of those things where most of the time it’s not going to be an issue, but every once in awhile, it will happen.

-- Clin

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Redoak49

2907 posts in 1829 days


#6 posted 11-14-2016 01:04 AM

I will not use a blade that has been involved in a Sawstop trip. There is no way to tell if there is any kind of damage to a tooth. I just do not want a tooth coming off at me. Others may look at the situation differently and use such a blade.

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rwe2156

2719 posts in 1321 days


#7 posted 11-14-2016 01:25 AM

Seems SS works on a lot of things besides flesh.

At $150 a pop + a ruined blade it pays to test all kinds of unusual material.

Then when you put it in bypass mode you’ve defeated the purpose of the saw…..

-- Everything is a prototype thats why its one of a kind!!

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clin

754 posts in 836 days


#8 posted 11-14-2016 02:04 AM



Seems SS works on a lot of things besides flesh.

At $150 a pop + a ruined blade it pays to test all kinds of unusual material.

Then when you put it in bypass mode you ve defeated the purpose of the saw…..

- rwe2156

Cartridges are about $70 not $150. I agree that bypass, well bypasses the safety mode, but it hardly defeats the purposes of the saw. It’s main function is to cut things and SawStop saws do that very well. I’d much rather have a saw that requires me to bypass a safety feature occasionally, then to never have that safety feature at all. We all do that every time we remove our blade guards to make a cut.

But yes it hurts a bit to trigger the saw and have to spend $70 + a blade to replace things. But I’d be more than happy to do that even once or twice a year if it meant never cutting off any fingers. One trip to the ER, for a serious cut, would pay for a lifetime of cartridges and saw blades.

-- Clin

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AlaskaGuy

3662 posts in 2149 days


#9 posted 11-14-2016 02:58 AM



Seems SS works on a lot of things besides flesh.

At $150 a pop + a ruined blade it pays to test all kinds of unusual material.

Then when you put it in bypass mode you ve defeated the purpose of the saw…..

- rwe2156

Using your figures “how to you test a all kinds of unusual materials at 150 a pop”? sounds pretty expensive.

Why did they put a by pass switch on the saw if you shouldn’t use it?

-- Alaskan's for Global warming!

View clin's profile

clin

754 posts in 836 days


#10 posted 11-14-2016 05:13 AM


Using your figures “how to you test a all kinds of unusual materials at 150 a pop”? sounds pretty expensive.

Why did they put a by pass switch on the saw if you shouldn t use it?

- AlaskaGuy

When it is in bypass mode, the indicator lights tell you if it would have triggered on the material. So that’s how you can test something without actually triggering it.

-- Clin

View Carloz's profile

Carloz

989 posts in 432 days


#11 posted 11-14-2016 05:26 AM


Your body conducts electricity and that is how the system detects flesh. I knew metal would do it, anything that is electrically conductive. DanielP is right, make sure you use the bypass next time.

- bigJohninvegas

Actually, the system works on capacitance not conductance. While there needs to be conductance in order for the system to determine the capacitance it does not fire because a conductor touches the blade but fires because what touches it is conductive and ADDS capacitance (ability to hold electrons) to the system. If it fired based on conductance for something to fire the system a circuit would need to be completed.

- AHuxley


I had an impression that you do notqiite understand what you write. A capasitive detection (like on iphone touch dcreen) would be the case where the system reacts before touching the saw. That is clearlh not the case. if a small metal object like a nail touches both the table and the blade the system goes off although it would not following your theory.

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AHuxley

652 posts in 3162 days


#12 posted 11-14-2016 06:36 AM


Your body conducts electricity and that is how the system detects flesh. I knew metal would do it, anything that is electrically conductive. DanielP is right, make sure you use the bypass next time.

- bigJohninvegas

Actually, the system works on capacitance not conductance. While there needs to be conductance in order for the system to determine the capacitance it does not fire because a conductor touches the blade but fires because what touches it is conductive and ADDS capacitance (ability to hold electrons) to the system. If it fired based on conductance for something to fire the system a circuit would need to be completed.

- AHuxley

I had an impression that you do notqiite understand what you write. A capasitive detection (like on iphone touch dcreen) would be the case where the system reacts before touching the saw. That is clearlh not the case. if a small metal object like a nail touches both the table and the blade the system goes off although it would not following your theory.

- Carloz

The Sawstop uses a capacitance sensing feedback loop to determine when to fire, period.

Some basic capacitive touch screens do not require pressure BUT they still require being touched with something conductive but the conductive material does not have to complete a circuit. What they sense is something that can hold an electrical charge like human skin. What you are talking about in regards to capacitive touch screens are what are referred as PCT or projected capacitive touch displays and use different technology than the Sawstop.

Again, the Sawstop is not sensing a conductor but sensing something that has capacitance, though I understand why it might appear that way to someone that doesn’t understand what exactly is going on. It works in the same way a touch lamp works. The blade acts as the antenna and is charged with a high frequency sine wave that alternates the positive and negative charge imbalance on the surface of the blade when you touch it you bleed off electrons to charge your body (like a capacitor charging) this increase in current is detected and if it is above the programmed threshold the brake will fire.

Again, the antenna (blade) has to be touched with something conductive to fire BUT in an electrical sense it is not measuring conduction but capacitance.

View jklingel's profile

jklingel

63 posts in 997 days


#13 posted 11-14-2016 07:07 AM

Wow. Thanks for all the informative replies! Yes, I re-used the blade. No, I never even thought of bypass mode; spooky, but maybe worth it now and then. Thanks, all. john

View AHuxley's profile

AHuxley

652 posts in 3162 days


#14 posted 11-14-2016 08:36 AM

All that typing and I forgot to address one of the issues that came up, static electrical discharges and the firing of a Sawstop. This can happen but it should be very rare AND Sawstop will replace a cartridge fired due to static electrical discharge, send the cartridge back and they will read the memory and can determine the mode of discharge. It is pretty simple how they can see this.

To sorta see what happens is the blade when on and in “safe” mode it has a static electrical field on the blade itself (set up by the high frequency sine wave that sets up the reversing positive and negative charge imbalance) and it is looking for a flow of electrons from this antenna to skin but could be easily fooled by the flow of electrons into the antenna from a static discharge from cutting insulation foam or other polymers like PVC. This is a case where using the saw to “test” the material may well not work since the act of cutting can create the static charge.

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jklingel

63 posts in 997 days


#15 posted 11-14-2016 06:13 PM

Very good to know. john

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