School #1: SawStop's Don't Like Nails

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Blog entry by Michael J. Moore posted 08-31-2011 09:54 PM 3725 reads 0 times favorited 19 comments Add to Favorites Watch
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Just a quick update, other than boring all of you with shop safety info I’m gonna start off by posting some meat. This week our shop manager had a false trigger with one of our 4 SawStops at the college. Now I think pictures speak louder than words so I’ll just show you the deal.

So yeah, don’t run construction grade lumber through your SawStop. It maybe able to cut the occasional brad nail or staple, but as you can see, no framing nails. After all is said and done your looking at about $250, so it’s not that cheap to have a false trigger.

I’m sure I’ll have more interesting things to post as the weeks progress, but that’s all for now.

-- Michael Jos Moore | Farmington, UT

19 comments so far

View Grandpa's profile


3263 posts in 3182 days

#1 posted 08-31-2011 09:58 PM

My understanding is it can’t cut a staple as small as we use in the office on paper. It has current on the balde and it checks for a conductor.

View rsain's profile


50 posts in 2995 days

#2 posted 08-31-2011 10:01 PM

Did you pee your pants when it went off? lol.

$80 bucks for a new brake. Unless it’s the dado – I think it’s 90. Plus a new blade.

Cheap compared to a visit to the hospital for a finger reattachment.

The SS does not like metal at all! Very common to pop one off with a nail in the lumber or with the miter gauge. Dont forget, you can always turn the safety off if you’re worried about your lumber.

- ryan

View Bertha's profile


13567 posts in 3200 days

#3 posted 08-31-2011 10:02 PM

Looks like it got into that nail a bit, Grandpa. That’s one expensive nail. Michael, be prepared for an outburst of comments below. Nice unique in the background!

LOL with Ryan. Definitely turn the switch off on your $5000 flesh-sensing saw if you’re uncertain of the content of your lumber. That’s what I’d end up doing;)

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Joe Watson's profile

Joe Watson

316 posts in 4053 days

#4 posted 08-31-2011 10:40 PM

few years ago i picked up a small metal detector from Harbor Freight for looking for nails and other metals. you might consider it too. i recycle woods is one reason i tend to be cautious.

-- Got Wood?

View Michael J. Moore's profile

Michael J. Moore

52 posts in 3377 days

#5 posted 08-31-2011 10:46 PM

Grandpa: We were told in the safety porting of the class, that focused on the SawStop, that it would cut a small nail or staple if it were not close to anything that it could ground to. I guess that’s not the case.

Ryan: It happened when everyone was being instructed on the Unique so nobody but the shop manager got to see it. I’m not sure about the prices for replacement outside of the total bill for repair being at or around $250. It may be that each of the 4 machines at the school are the SawStop Industrial Cabinet Saw 7.5hp Models and their brakes may just cost more. One thing I do know is that they try not to risk anything so they have their rep come out and do the install and reset for them to to make sure it works correctly.

Al: The Unique is really nice. I find it more comfortable than standing at any of the Powermatic PM2700 Shapers we have or even a router table for more than one reason. In the Cabinetmaking Class it is the most time saving machine we use out side of the Edge Bander beast we have and the Altendorf F45s. It is a pretty nice shop.

-- Michael Jos Moore | Farmington, UT

View BritBoxmaker's profile


4611 posts in 3543 days

#6 posted 08-31-2011 10:47 PM

I second what Joe said. A hand held metal detector is a smaller outlay than a decent tablesaw blade and its the work of seconds to check suspect timber (lumber).

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging.

View Michael J. Moore's profile

Michael J. Moore

52 posts in 3377 days

#7 posted 08-31-2011 10:53 PM

Joe: We, the students, are not allowed to use any reclaimed or used lumber on the machines in the shop and I’m pretty sure they have a metal detector for projects at the school that require those sorts of materials. As I recall this was just a quick rip for the framing class that was not inspected first. If it were my SawStop you could rest assured that I would take every precaution necessary to make sure I was not going to ruin a blade or break. I just don’t have that kind of money. Great advice though, thanks!

-- Michael Jos Moore | Farmington, UT

View steviep's profile


233 posts in 3154 days

#8 posted 08-31-2011 11:19 PM

I am surprised that the cut is halfway through the nail. I am intrigued with the Sawstop, this is more information to mull over. I am amazed at how $250 seems so expensive for a false trigger and how cheap it compares to surgery. Heres to hoping none of us have to find out.

-- StevieP ~ Micheal Tompkins - you were not here on earth long but left a giant mark on us. RIP Brother

View Joe Watson's profile

Joe Watson

316 posts in 4053 days

#9 posted 08-31-2011 11:38 PM

didnt realize it was at a school. i only paid 15 bucks for the detector i bought.

-- Got Wood?

View Fuzzy's profile


298 posts in 4495 days

#10 posted 09-01-2011 12:21 AM

It looks as though it took a pretty decent chunk out of that nail, which might explain the triggering of the brake. If the metal dust coming off of the nail smeared in an arc … it may have created a path for the charge on the blade to dissipate to the saw itself, causing the trip. Kinda like how in the old days, you would sometimes get a car that wouldn’t run because of carbon arcing inside the distributor cap … clean it out, and it ran like new.

-- - dabbling in sarcasm is foolish … if you’re not proficient at it, you end up looking stupid … ... ...

View Rob_G's profile


13 posts in 3126 days

#11 posted 09-01-2011 12:42 AM

The sawstop doesn’t look for current, so the nail doesn’t need to be grounded. A person who cut their finger isn’t usually grounded because they’re frequently wearing rubber soled shoes.

The Sawstop looks for a change in the capacitance/inductance of the blade. I believe that’s done by hooking the blade to a transistor gate and using the capacitance change to open a source circuit that blows a fuse holding back the blade retainer.

View Freakazoid's profile


68 posts in 3285 days

#12 posted 09-01-2011 12:49 AM

I just had the same thing happen last weekend – I missed removing a screw that was still in the wood before cutting it. I saw the flash, heard the “pop” of the charge, but since things like that are remembered in slow motion, I distinctly remember hearing no more noise before the flash cleared, and it was as quick as a flash from a camera. I already had confidence in the saw’s safety system, but now I KNOW it works.

-- I can complicate anything

View Scott's profile


153 posts in 3479 days

#13 posted 09-01-2011 01:40 AM

I agree with Rob G. It wasn’t a false trigger at all, it was a real trigger.

View Sarit's profile


551 posts in 3647 days

#14 posted 09-01-2011 04:22 AM

Now you have some wall art.

View Michael J. Moore's profile

Michael J. Moore

52 posts in 3377 days

#15 posted 09-01-2011 05:07 AM

I can tell you this, if it was supposed to trigger with a nail then it’s not very comforting to see how far the blade went into the nail before the brake kicked in. It still is the safest saw on the market though so no real complaints here.
It just kinda sucks that something like the SawStop brake technology can go to a restrictive patent. If I designed something that helped to prevent life changing injuries I would at least license it out so other saw companies could use the design to help prevent more injuries. I might charge and arm and a leg (i know) for it but it just seems like the more ethical thing to do, just a though.

-- Michael Jos Moore | Farmington, UT

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