Saw Stop

[Larry Blanchard]

No, the trunnions, bearings, etc. are built extra heavy to absorb the shock. IIRC, the trunnions alone weigh over 300 pounds.

[Jim Northey]

Ok I do not disagree with the safty aspect o the saw stop . What I do have is a problem with the above statment ( if it's word for word from their newsletter) . As I understand it , a blade with 1/8 " kerf give or take, spinning at X amount of revolutions per minute stops in 0.0whatever seconds and comes in contact with any body part can leave nothing more than a scratch. It's to late in the day and I've had more than a few so I'm not going to do the math on how many teeth will have contacted the flesh on that body part . Anything 1/8th wide is not what I would consider just a scratch. A minor cut I can understand but a scratch is what you do with a fingernail or something you get when you piss off the cat. Jim

[Jason]

I'll do the math

assuming a 3450 RPM table saw with a 10 inch 65 tooth rough cut blade

From a fixed point, 65 teeth @ 3450 RPM gives us 3738 teeth per second passing a fixed point. Sawstop claims to be able to stop the blade in

5ms on a bad day, so that leaves us with 19 teeth passing over your finger in the time it takes the blade to stop. Now that's assuming that you're able to instantly insert your finger into the path of the blade. You would have to be moving your finger at over 150 ft per second or 103 mph to make that happen. Since sawstop is assuming 1 ft per second or .7mph, your finger will make it roughly 1.525 mm into the blade. Skin varies in thickness from between .5mm on your eyelids to 4.5mm on your hands and palms, so if the saw is able to do it's job in 5ms and you're honestly just not paying attention and aren't doing something boneheaded like trying to force the board through the blade, you should have a scratch roughly 1.5mm deep. It'll bleed, but not for long.

Take this for what it's worth, it's just math. Math and reality often don't play well together, but the sawstop theory is sound. BTW, I'm not affiliated with sawstop, I'm just an engineer and number crunching is about as wild and crazy as I get on a Friday night.

Jason The place where you made your stand never mattered, only that you were there... and still on your feet

Jim Northey wrote:

[craig.colvin]

Hi -

I'm the owner of The Sawdust Shop who's newsletter was referenced earlier in the thread.

Here are my observations of having used the SawStop for the past 18 months in my woodshop and having sold dozens of them. I have also done the hot dog demo over 20 times.

Regarding the speed and depth of cut. Feeding at a slow rate makes it almost impossible to find the cut on a hot dog. When I demo I feed as fast as possible can, way faster than I would ever feed when cutting, The resulting cut is approx. 1/64" deep. It would bleed, and require a band aid, but no stitches.

Regarding the forces to the trunnion. The SawStop is designed to absorb the forces that occur when stopping the blade. The arbor is about twice the diameter of competing arbors, the trunnion is heavy duty and the entire trunnion assembly breaks free at the front of the saw and pivots down to absorb the force of the stopped blade. This is what causes the blade to drop below the table when the brake activates. I was skeptical at first too, but have had no problems with my saws after repeated firings of the brake system.

Regarding misfires. There were a few in the first month we had the saw. This was traced to noisy power and SawStop sent us some filters that corrected the problem. Never had a misfire since on the 2 saws in our woodshop. All current saws that are shipping come with these filters and we haven't heard of any misfires from any of our customers.

Wet wood. It will fire if it cuts VERY wet wood. Basically there has to be contact between the blade and your hand or the blade and the table via the water in the wood. If you suspect wet wood there are several ways to test it prior to cutting to prevent triggering the brake system. When the saw is off (blade not spinning) you can touch the blade with the wet wood, or with your finger and a red indicator light will flash to indicate that it would have fired if the blade had been spinning. You can then use the bypass key to disable the brake system for cutting that piece of wood. We have cut a lot of wet wood and have never had the system fire. It has to be very wet.

We sell Jet, Powermatic, ShopFox, and SawStop table saws. The SawStop has the best quaility of the four and is probably the finest manufactured piece of equipment I have ever used. My theory on this is that because they were the new kid on the block they were determined to make a high quality machine so that the quality would never be questioned and would not be a barrier to a sale. Even without the braking system I would purchase the SawStop. It's just that good a machine.

Other nice features, the riving knife, the quick-release for changing between the guard and riving knife, the zero clearance inserts lock in to the saw, power disconnect switch, heavy cast iron table (no vibrations), air-assist shock on the elevation control.

Someone asked for cons. The only con I can come up with is that the dust collection could perhaps be better. It's way better than most saws but a lot of sawdust still collects in the cabinet. It's a minor thing.

Anyway, that's my $0.02.

-- Craig

[craig.colvin]

Hi -

I'm the owner of The Sawdust Shop who's newsletter was referenced earlier in the thread.

Here are my observations of having used the SawStop for the past 18 months in my woodshop and having sold dozens of them. I have also done the hot dog demo over 20 times.

Regarding the speed and depth of cut. Feeding at a slow rate makes it almost impossible to find the cut on a hot dog. When I demo I feed as fast as possible can, way faster than I would ever feed when cutting, The resulting cut is approx. 1/64" deep. It would bleed, and require a band aid, but no stitches.

Regarding the forces to the trunnion. The SawStop is designed to absorb the forces that occur when stopping the blade. The arbor is about twice the diameter of competing arbors, the trunnion is heavy duty and the entire trunnion assembly breaks free at the front of the saw and pivots down to absorb the force of the stopped blade. This is what causes the blade to drop below the table when the brake activates. I was skeptical at first too, but have had no problems with my saws after repeated firings of the brake system.

Regarding misfires. There were a few in the first month we had the saw. This was traced to noisy power and SawStop sent us some filters that corrected the problem. Never had a misfire since on the 2 saws in our woodshop. All current saws that are shipping come with these filters and we haven't heard of any misfires from any of our customers.

Wet wood. It will fire if it cuts VERY wet wood. Basically there has to be contact between the blade and your hand or the blade and the table via the water in the wood. If you suspect wet wood there are several ways to test it prior to cutting to prevent triggering the brake system. When the saw is off (blade not spinning) you can touch the blade with the wet wood, or with your finger and a red indicator light will flash to indicate that it would have fired if the blade had been spinning. You can then use the bypass key to disable the brake system for cutting that piece of wood. We have cut a lot of wet wood and have never had the system fire. It has to be very wet.

We sell Jet, Powermatic, ShopFox, and SawStop table saws. The SawStop has the best quaility of the four and is probably the finest manufactured piece of equipment I have ever used. My theory on this is that because they were the new kid on the block they were determined to make a high quality machine so that the quality would never be questioned and would not be a barrier to a sale. Even without the braking system I would purchase the SawStop. It's just that good a machine.

Other nice features, the riving knife, the quick-release for changing between the guard and riving knife, the zero clearance inserts lock in to the saw, power disconnect switch, heavy cast iron table (no vibrations), air-assist shock on the elevation control.

Someone asked for cons. The only con I can come up with is that the dust collection could perhaps be better. It's way better than most saws but a lot of sawdust still collects in the cabinet. It's a minor thing.

Anyway, that's my $0.02.

-- Craig

[B A R R Y]

They have nothing to do with hand speed, which is the statement I responded to.

[Leon]

Craig, where have you been hiding? :~) Nice to hear from another person with extended experience on the machine.

Thank you for the comments.

[Leon]

Its speculation and forming ones opinion from a guess that starts ill informed comments about a tool.

[Scott Lurndal]

The point is that your hand shouldn't be anywhere near the blade, no matter the speed.

scott

[B A R R Y]

I'm totally jiggy with that, as well as a believer in SawStop technology. I'm big on push blocks and jigs, so that I'm comfortable without a SawStop in my one-man shop.

SawStop firings are about _accidents_!

However, all of the demos always have the hot dog moving so slowly, not like my hand might be moving when ripping.

[tomwalz]

In no way did I mean to denigrate the Saw Stop. My point was that you can still get hurt with it.

In retrospect my answer was probably more reflexive than it should have been. When I teach safety I emphasize that nothing is completely safe and I show how it is possible to get hurt no matter how far fetched.

I once had an employee raise a guard and put her hand under a cutter then flip both the on switch and the master safety switch while her hand was under the cutter. When we designed the machine we were sure no one was going to get hurt with it. Fortunately she wasn't hurt badly because of the safety aspect but she was still hurt.

When we build equipment, we never tell people it is safe. We always emphasize how to use it safely. We also always design in as much safety as we can.

tom