I did set off my SawStop with my thumb. After over fifty years of operating table saws and not cutting myself, I got stupid and ran my thumb into the blade. I did get a little more than a nick, and it did bleed. It also hurt......but my thumb was saved.....but my ego was bruised. I thought to myself, "How could I be so stupid???" Also, when you get tired and fatigued, get out of the shop.

Another possibility, home depot stores their wood in the river prior to sale.

Craig should get employee of the month for his part in this! Such dedication!! Way to go Craig!

Thermal conductivity is how well the metal conducts heat, not electricity (more relevant in cooking pans, lol). Fortunately, sources seem to say that aluminum is much more electrically conductive than galvanized steel too

A hidden nail was embedded in a piece of wood I was cutting and made a spark, but didn't set off the blade brake. Contacted SawStop about why it didn't and they responded with the following. Nails and screws in and of themselves are not conductive enough to cause activation. However, if the operator or the table top is in direct contact with the other end of the nail or screw, a conductive path with be completed as if the blade contacted the person or grounded surface. In response to your question, the list of electrically conductive materials below are examples of materials which can cause an activation of the SawStop Safety System unless the Safety System is placed in Bypass Mode. • Conductive metal sheeting such as Aluminum or Copper. • Grounded metal (e.g., the blade guard splitter, the riving knife, a metal jig, or a metal tape measure touching blade while in contact with the table top.). • Relatively large masses of ungrounded metal, such as a tape measure not in contact with the table or a combination square or ruler. • Foil-backed insulation. • Mirror-backed plastic. • Metallic paint layers (e.g. gold paint on picture frames). • Conductive laminate layers (some countertops have a foil layer behind the Formica). • Materials made from, or containing carbon, such as black melamine or plastic, some black paints, carbon composite or carbon fiber materials • Electronic circuit boards (because of the conductive layers). • Uncured glue layers (wet glue is electrically conductive). • Wet pressure-treated materials (the chemicals used to pressure-treat wood can be electrically conductive when the wood is wet). • Very wet, especially wet cedar. If you are in doubt about whether any material poses a risk of activating the cartridge, you can place the saw in Bypass Mode and make a test cut or two. If the material would have triggered the cartridge, the red LED will blink quickly (until the blade stops) to indicate that contact was detected during bypass operation. In this case, you will need to finish all cuts of this material in Bypass Mode to avoid an unintended activation of the cartridge. If the red LED does not start blinking during the test cuts, you can proceed to cut in normal mode. Note: Every time saw is turned off it resets to normal mode and is no longer in Bypass Mode. Nails and screws in and of themselves are not conductive enough to cause activation. However, if the operator or the table top is in direct contact with the other end of the nail or screw, a conductive path with be completed as if the blade contacted the person or grounded surface.

It’s all about capacitance. The system senses the sudden increase in capacitance on the blade. A nail isn’t big enough to hold capacitance. You can also do this same test way easier without tripping the brake by touching the material to the blade while looking at the lights on the interface near the switch. Anything that would trip your brake will flash a light on contact at the blade.

Great video. Note that with your Saw Stop ready but not spinning you’ll have a green LED. To see if something will drop the blade, push it against the blade while the blade is sitting still such as your finger or wood that is wet with salt water. If the red LED starts flashing then your blade will drop when it is cutting but this testing won’t drop the blade as long as the saw is still.

I feel many of the myths about material (like foam, cardboard, etc.) setting off a SawStop are caused by woodworkers doing something stupid, then telling their significant other “I don’t know what happened honey, I was just cutting cardboard.” I have stood next to the SawStop rep at a tool sale and heard a couple of these stories and after they leave he has made some interesting comments about the story’s lack of credibility. The most interesting story I heard was about an older gentleman that set a SawStop off at Woodcraft during a class, reportedly just cutting wood. The instructor changed out the blade and cartridge and class resumed. About 15 minutes later “boom” he trigger it again. In a more detailed review of the gentleman’s technique, and the small nick on his thumb, it was found he would turn the saw off and place his thumb on the side of the blade to slow it down quicker … setting the saw off.

There is rigid foam insulation with foil backing, typically aluminum. This would explain the instance of the saw stopping when cutting foam.

Hey Jason, thermal conductivity and electrical conductivity are two different things. Thermal conductivity is how much a material can transfer heat energy. Electrical conductivity is the ability to allow electrons to move. While i haven't looked at the sawstop too closely, i'm assuming it works on another electrical property of capacitance. This is similar to how touch lamps work. Everything has capacitance but the value of it depends on the size of the materials and the dielectric involved (see wikipedia). Its likely a change in capacitance value is likely what sets the saw cartridge off. It shouldn't matter if its galvanized steel or aluminum it will have to do with the size and shape of the object. Similarly, water is actually a bad conductor until it get impurities dissolved in it like salt (its the salt ions that conduct). It could depend on local conditions like humidity and if any contaminates are present to allow it to conduct your capacitance...

Pressure treated lumber has tripped my Saw Stop along with: * Aluminum *Plexi Mirror * Some laminate ( metal or particle metal) * Different types of flooring *Carbon Fiber The sound the Saw Stop makes when engaged is like a gun shot. It will scare you when it happens, but it will remind you to bypass the safety when cutting materials such as aluminum. The safety bypass would be a great thing to cover in your video. The procedure only bypasses the safety for one cut until the switch is turned OFF. Great video!

Thank you for this video, which cost a few bucks to make considering those brakes are $120 each, but I think this will educate a lot people on the saw stop technology.

no matter what, trading a blade and or cartridge for a finger is a pretty is a darn good deal

we have saw stops where I work, and we use foil backed insulted foam panels, and the backed does trip it

Had a friend get into progressional woodworking. Bought a sawstop rather quickly and almost immediately posted a picture of a tiny little cut on his thumb; like he slipped with a fine rasp. Sawstop saves fingers, no question.

Wet wood set off my Sawstop last spring. I was making a rain water stand for my rain catchment tote. I was ripping some pressure treated lumber that had been sitting in the Oregon winter sunshine (AKA Drizzle). I want to be clear this wood was dry to the touch. The PT 2x4 set off my brake at about 2 inches into the rip. Your results may vary, but the new brake was a $105 mistake that I do not wish to repeat. My day job has been in ultra-pure water and water treatment for the last 25 years. It is my guess that the toxic metal salts that PT is impregnated with (chromated-copper arsenate) --substantially increases the salinity and the conductivity of the "distilled" rainwater that we are likely to find in wet wood. The fortunate coincidence is that we all have salt-water coursing through our veins. (Harrr).

Great video. The one you didn’t test was pressure treated wood. That’s what I have heard unknowingly sets it off the most.

After these tests SawStop should be offering you a sponsorship. You've convinced me that when I replace my table saw I'll seriously consider a SawStop system.

I guess over the decades and all the videos made nobody was willing to spend money on a box of cartridges to run all of these tests. But you stepped up to it and may have saved peoples fingers as a result. The entire world owes you a thank you at least the subset that has a tablesaw.

Craig plays the "comedic straight man" so well! 😂

Most of the wet wood triggers are pressure treated boards. These are both soaking wet and treated with copper making them extra conductive.

I have a CO2 laser that I used to try and cut a 3/4 piece of plywood as a test. The wood was very charred around the edges and the cut was not successful. The charring was all the way through the 3/4 piece of ply, and was quite thick. I cut the wood into scraps and when my SawStop hit the carbon burned area, it deployed the brake. I called SawStop to ask and they reminded me that carbon from burned wood is very conductive. Lesson learned.

Thank you Jason - these devices are important and thanks for discussing them! In 34 years of old home restoration I've employed two carpenters. The first had a short finger, made smaller by a sliding compound miter saw. The second had a thumb that he had reattached after cutting it off on a chop saw - he often said though it functioned okay it still hurt after 5 years and wanted to get it removed permanently. Thankfully neither got injured while working at our home. I'm the only person who got badly cut up on woodworking equipment in my own home. I got a bad slice off a table saw, long before this technology was available, losing a hunk of skin off my thumb. It has healed and is doing fine, works okay, just looks a little weird. Stay safe and thanks again for the vid. If this helps one person think twice to be safe that's a big deal!

I feel personally attacked.

We set our Sawstop off twice. Once on the carbon on MDF left from a CO2 laser cut. The other was very wet eucalyptus wood. I made many cuts off the wood before the safety mechanism tripped. Lessons learned. I use bypass with any wet or weird material.

I have had two drops, one that I can explain (thumb) and one that I can't. Two Forrest WWII blades were involved, so naturally, once I got the aluminum blocks off, I sent both back to Forrest for repair. One just lost a carbide tooth, easily fixed, and the other had broken an aluminum tooth support, which they couldn't fix. Still, I got one blade fixed, balanced, and sharpened for about $35 with postage, so good to know! It works perfectly again. Second, you can send the brake controller (just the blue bit) to Saw Stop, and they will look at the data from the trigger to determine if it was a legit trip. They'll replace the cartridge if it's not. It would be interesting to see what SawStop's reports on all of Jason's cartridges said.

the balloon on the stick got me. Your jolt when it popped made me laugh

I’ve saw a Saw Stop Saw do that probably 5-6 years ago & I was truly impressed. I don’t have a workshop & I’ve never owned a table saw, but I felt comfort in knowing my fellow Woodworking people would be able to walk away from a “Near Debilitating” injury with all of their fingers intact. Thank you SawStop.

Lol, that jump cut near the end made me laugh out loud. Very entertaining video!

Always admired the "Harbour Fright" good business man!

Amazing amazing amazing amazing. THE saw stop video of all saw stop videos. Testing exactly what so many of us wonder before delving into the world of saw stop AND… how far can one machine go. The best. Thank you

I did set mine off with wet cedar. I had made multiple cuts through this lumber and for some reason a random board set it off.

We had 3 Saw Stop saws in our shops and the only time we saw them trigger was for fingers or pressure treated wood. I know saw stop tools are expensive; but they are extremely cheap when compared to an emergency room visit. Not to mention any reconstructive surgery. Back in the day before we had these tools I got nibbled on and lost a good deal of the skin and pad of my left thumb. It was covered by worker's comp (thank the Lord!) and the final cost of the E-room, skin graft surgery, follow-up doctor visits and physical therapy was over $20,000. The cost of all three Saw Stop table saws was just north of $10,000. Like everyone always says, "Do the math." We worked with students at a large land grant university and figured that we couldn't afford NOT to get the Saw Stop saws.

Thermal conductivity is about heat, not electricity. Think of holding a stick by one end while the other is on fire vs holding a metal rod that's had the opposite end in a fire for some time.

The Hotdog hand, had me rolling 😂😂😂😂

OK, when you pulled out that breakfast burrito I just burst out laughing. Hilarious!

I set off my 1.75 hp 110V Sawstop when the blade touched the head of a steel wood screw in 3/4" plywood.

I disengaged my SawStop brake from my blade by placing the blade in a vice and using a brass hammer, I tapped the brake off. I thought the blade looked real good, but when I had it sharpened, the shop said it was a bit bent, but they straightened it. It works fine now.

Wet wood will trigger the sawstop. I have done it, unfortunately. But I think the key is it wasn't just wet wood. It was 3/4" wet pressure treated plywood. I think the copper based fluid they put in the plywood has enough capacitance to fire the brake. A few weeks later, I was cutting some EPS foam that was going to be used as insulation under my concrete floor. It had a foil face to it, and I didn't think about the brake with the foam. I don't know if it makes a difference, but I had the foil face down (touching the table top), and that triggered the brake. One of the two blades lost a tooth. But that was cheap blade and I was planning to replace it anyways. The other was Woodworker II and it was absolutely fine and I'm using it still.

After hearing a common theme "It happened so fast" or "what was I thinking". I did the math and bought a SAW Stop. Funny thing is I rarely use it since adopting mostly hand tool work. I have a friend that last week put his thumb into the saw blade. Nice video!

Craig, thank you and your hair for your contribution to science

With out a doubt, the most educational and entertaining woodworking channel on you tube, perhaps the world. Thanks for going broke running this test. Great stuff.

That took a LOT of effort. Thank you. Very, very informative.

Impressive pile of “money” in that pile of expended stopper doodles. Thank you, thank you, thank you for this video! You da man!!!

I think the fence of the Rockler sled was setting it off because metal was connected to the table of the saw through bolts and miter slots, etc completing the circuit. The nails and staples didn't set it off because they were floating in the wood and therefore insulated. If you'd have driven a nail deep enough, or flipped the board over, so the metal was in contact with the table, it would have set the saw off, I bet. Either way, you don't owe anyone any bourbon ;).

What we really discovered is that the future material to be used for our energy transmission is hot dogs.

Love the addition of the fast forward sound effects lol. Very JD-esque 😂

Yup. I have my personal, triggered cartridge that I caused by barely touching a blade. It had spun down, almost to nothing, after I had turned the the machine off. I didn't think I had even touched the blade, and, eventually, decided that a tiny abrasion on my finger must have been the point of contact. It didn't even bleed. The thing works.

"What did we learn in this video?" Well, this gal learned she was simultaneously more and less afraid of table saws. I love the idea that I'd get to keep my digits, but the sound of the blade locking on the break would probably give me a minor heart attack. Lol

That power off safety on feature is clutch

Watched this Saturday. Sunday my brake activated with wet, pressure treated wood. Give that a shot. It ran one plank, then tripped on the second.

Wow, thank you so much for doing this video. I have a Sawstop and was really interested in your results.

I just made dados on 4 x 4 posts that were quite wet yesterday and i forgot to deactivate the system. It took 5 seconds and boom, the dado blade was stuck in the cartridge. My experience is that it does work with wet wood.

Very impressive video Jason, especially the participation of JKM. I still think people should be scared shitless of kickback, even if they have a Saw Stop.

Soak the board in saltwater. You need some salinity in the moisture for it to conduct electricity.

The one point that I haven’t seen mentioned in any video of these Saw Stop is after the brake has been activated and the blade has dropped , after replacing the brake and blade the next step is to turn the handle for raising and lowering the blade down to the lowest setting before the height adjustment actually works again. After witnessing the hotdog 🌭 test at the woodcraft in Springfield Oregon and everyone walked away I stayed and watched them replace everything, I asked after the blade drops how do you get it to raise back up , it obviously wasn’t attached anymore to the mechanism that raises and lowers it , this part is just as important as the technology . Thanks the video

I always enjoy your videos and always find humor in them, but I actually laughed out loud when I heard “so that means a tortilla will set it off”. Thanks Jason.

Gentlemen, keep the magic hotdogs off of the table saw.

You just sent chills down my spine!! I had to close my eyes when your finger was the test subject 😮

I got a Sawstop about 6 years ago and wouldn't even consider another brand. I have also wondered about whether the mechanism works as the blade is slowing down, and I'm glad to see it does. Thanks for taking one (or 7) for the team, Jason!

Current is not measured in volts - He got the point across though. Aluminum is likely the most common metal cut on a table saw, so for some folks that's an issue. If you rub a couple pieces of that foam together a bit you'll definitely get a static charge. Thus, if you grab a sheet off of a stack of foam panels you would have a higher potential for tripping the saw stop. You spent a lot of money to make this video, and I thank you!

Your crosscut sled has hardware through the aluminum down through the base. That completes the circuit. The nail in board just never happened to touch the table and blade at same time

Most mirrors are made with a layer of silver sprayed onto it, and silver is the most conductive metal we have, so that would make sense.

Yes, 30-32% is what's called the fiber saturation point (FPS, Bruce Hoadley). Inside wood the cellulose has bonded to as many water molecules as possible which, bonus fact, also makes the wood swell which is why you space your deck boards so when they get wet they don't split and warp. Everything beyond around 30% in just about every wood is actually filling the cells and depending on those cell structures could hold onto water a long time (oaks in particular) or release it pretty quick (pines, cedars and spruces). Also to really get a lot of water in the cells you have to completely submerge the wood for several days and not just let it sit on top of the water. That being said, the amount of water you tested with is the most realistic wood saturation you'll see, no reason to waste another cartridge. I enjoyed the Mythbusters style testing for sure!

What you’re likely to trigger the most….is that AvE dude😂

love that you went and soaked a board in a river for two days instead of doing it in a tub

I've never had a visceral reaction to an intro....until today...thanks.

Thank you for a very fun, engaging, and interesting video. I have been a hobbyist woodworker for many years, and this is the first time I have seen one of your videos. I subscribed immediately! You have a very good teaching style, and I can tell that you will make me a better woodworker! Keep up the good work! I just bought my own Sawstop less than a month ago, so this video definitely reassured me about my decision.

We need a crossover with ElectroBOOM to explain the electrical properties of the SawStop break.

Using a Forrest blade to test this is pretty heartless to us have-nots!

Jason, great video. One thing you didn't test was pressure treated wood. Shortly after getting my SawStop, I made several cuts through pressure treated 1/2 inch plywood. I couldn't turn my saw off other than to unplug it. It didn't set off the brake, however, it blew out my "Switch Box and Contactor Assembly". Replacement was expensive.

Thanks for showing all this in regards to the Sawstop as I am considering getting one

Thermal conductivity? That's not electrical conductivity, mate. Short the blade out to the table via the metal, see what happens then.

Water is not conductive. But salt water is. Soak the wood in salt water and the brake will go off. Treated wood will also set it off because copper is extremely conductive.

I literally laughed out loud when you tested the balloon! Priceless and entertaining.

We run a SawStop in the high school furniture class I teach and about 10 years ago a pitch pocket in a cedar 2X8 tripped the brake. Also, you can send your tripped brake to SawStop and they will analyze it and if it was skin contact they'll send you a free replacement.

Safety glasses,ear protection,tucked in shirts, and no unbuttoned long sleeve shirts and the proper handling of table saws. My jr high school wood shop teacher taught me well and as an incentive he would deploy the paddle of correction. Half inch thick and holes in it to suck up the meat as he would say plus good wrist action, guaranteed to lift you off the ground. My dad didn't use hearing protection for all those years he worked making cabinets and stuff. I felt sad for him one morning as it was sleeting outside and he couldn't hear the sleet bouncing off the window AC unit. I did get him a personal headphone amp that hangs around the neck so that he could enjoy hearing as well as watching his favorite tv shows. One day my dad accidentally cut off the end of his thumb while using a table saw at work. Insurance helped pay for heating fuel oil that winter. Us kids stayed warm. 😊

The answer has and always will be.......keep your hands away from the blade.

Our son worked in a shop with a SawStop. He said that cutting pressure treated wood would set it off.

Thank you for the experiments. Great video. We all sweat differently and in my case with damp boots or sneakers from walking in the yard, sweaty feet and a damp or wet board, if one hand was resting on the table and the other hand pushing the damp board into the saw I would be cautious about setting off the safety switch. Again well worth watching.

Dude please don’t become a caricature of KZfaq thumbnails. Sick of seeing every channels thumbnails slowly turn into dramatic open faced “everything is horrible” just for attention and clicks.

once again sir, the sound effects really do something for me when watching your videos, great touch!🤓

I'm glad I have a SawStop.............well worth the peace of mind.

I once tripped a dado cartridge cutting through wood glue that was still wet. Some glue found its way into a void in some plywood and hadn't tried by the time I made a cut, and it tripped the blade. But later I tested wet wood glue against a stationary blade to see if it would activate the blinking indicator, and it didn't.

Great Video. I have never commented on a video before but the comments on this one got to me. I have lost a finger and damaged another in a kick back incident on an older Craftsman table saw with no riving knife. I will never operate a table saw again without this technology. And by the way the sawstop I purchased is a huge upgrade in quality from my old Craftsman.The cost of the Sawstop was far less than the cost of the multiple surgeries I underwent.

Fantastic video. I love my sawstop and this is great info for the hobby woodworker like me. Thanks!

PLEASE TEST PRESSURE TREATED WOOD Here in sweden it is very common to use pressure treated wood for outdoor flooring etc. That wood contains different types of salt/cemicals and from the store it is usually very wet, probably more wet than if you put it into the river as water is pressed into the wood. Pine is most commonly used and after treatment it can be outdoors for several decades.

The one "wet wood" thing you missed was pressure treated wood. My dad set his off a couple times while ripping a bunch of pressure treated lumber … but in that case, SawStop told him it wasn't the moisture, but that the pressure treatment contains copper. The damp wood just made it more likely for clumps of wet coppery saw dust to build up inside the saw near the blade to the point that it activated the mechanism.

Great information. Thanks for the demo.

yaas king, I've hit tons of staples and nails and never set it off. I've had people argue with me on reddit over it.

Love how Jason just burns through $1,000 worth of Saw Stop brakes just for this video. I'm here for it buddy!

Ah good memories. My woodshop course in college had one of these. The rule was, if you triggered the saw stop, the ruined blade stopped by someone then got signed by them, and hung on the The Wall Of Shame as a warning to others.

I was cutting melamine that had been sitting outside for a long time with my saw stop and it set it off. I wasn't expecting anything like this although I had my saw set off before when I hit the blade with my aluminum crosscut sled. I was holding the fence when it went off. Since it costs about $200 to replace the brake and the blade, I now always turn off the stop feature when I'm cutting repurposed wood just in case there are any hidden pieces of metal. This is a great video to see what will set the SawStop off since you never know what will and what is safe. Thank you for spending all that money for replacement brakes so I don't have to. 😁

You sure kept me on the edge of my seat with this!

The one time we set our SawStop off was when a student touched the blade while adjusting the height. That’s because once the power is on, the current is going to the brake. The motor does not need to be engaged for that to happen. Nice expensive lesson, that.

This was informative and highly entertaining!!😂

The authenticity is impeccable. Love your videos brother

A capacitor is constructed with, basically, two conductive plates separated by an insulator. The aluminum plate is capacitively coupling to the tablesaw top, with enough surface area to make a "good" coupling that trips the detection threshold. A nail is too small to make a good sized plate that couples to the system. The whole thing works on a capacitive detection scheme, they note that in the patent. I design capacitive touch panels for a living, all of this is central to my work so it's really easy to piece this together :)

The wood that set mine off was treated wood. I set mine off a couple of weeks ago while it was off and winding down. It didn't "pop" so I thought it was fine. It felt as subtle as touching a cat whisker. Then when next I went to use it, I discovered it had been set off. I just couldn't hear it and it didn't drop but was firmly entrenched in the aluminum. Amazing technology. Also, reading all these comments, I think we can get a degree in electrical engineering. 😋

Electrician here. For metal, it's mostly based on resistance and conductivity. Aluminum is a much better conductor, but there are a lot of other factors also. The amount of material (the fence being much larger), being painted, galvanized coating, etc. As far as water setting it off, water is actually not very conductive by itself; it's the minerals in the water that can conduct electricity. If you used salt water, it would most likely have tripped. So for wet wood, it's based on what chemicals are in the wood that may trigger it.