Where do you stand when you saw?

[cgallery]

I've been following some of the SawStop threads at other forums and decided to watch some of the video at the company's web site. I've seen the video demo before, it is certainly impressive. This time I watched a movie showing a guy using the saw and getting distracted enough to cut his thumb off (a dramatization).

Anyway, watching the movie was hard because I saw the way he was holding the wood (w/ thumb extended into the cutting line of the blade).

I've always stood to the right of the fence, and guide the wood with my right hand and push with the left. I know I'm not in the ultimate position in the event of kickback. However, I try to keep my fingers as close to the fence as possible.

It seems standing to the left of the fence (and to the left of the workpiece) to avoid kickback adds to the risk of a cutting injury because you are working closer to the blade.

Where do you stand? And are you right or left handed?

And besides buying a SawStop, what is your one best safety tip to avoid fingers in blades (not limited to table saw).

[cgallery]

And another question that an expert (maybe Loring) could answer. The SawStop technology is impressive. But I wonder if it is the least-costly way to implement such a safety feature. I know there is a lot of momemtum involved, but I also know some miter saws have brakes. I'm sure sensing skin contact and then turning off the saw (which would "hit" the brake) would help. How do these saw brakes work? Could a better brake be made and connected to a skin sensor on the blade?

Maybe it wouldn't work as well as SawStop, but if it costs 1/10th as much to implement and meant you partially cut one finger instead of amputating all of 'em, maybe it would be a good compromise.

[MilDoc]

I stand well to the left, use featherbords to hold the wood to the rip fence, and push with block or other guide. But, if doing a sigle rip cut, no featherboard. My left hand holds the wood to the fence, well in front of the blade.

[Popeye]

I stand to the left of the blade and feed with my right hand and hold the work to the fence with my left. Have never used featherboards. Always use push sticks when the stock is less than 4". Never never ever ever take my eyes off the blade or feed with my hands in line with blade. Pat

[Ken Massingale]

I'm right handed and stand to the right. I'm more comfortable than to the left, less awkard, so for me, safer. I think it depends on the woodworker to find the position at any tool that is right for them.

Pushsticks, Grippers, whatever is needed for the particular task.
ken

[ChrisD]

I'm right-handed, stand to the left of the blade, push with my right hand, and keep the stock against the fence with my left hand. As my right hand gets closer to the blade, I grab a pushstick and continue feeding. I use a featherboard whenever possible and always have the riving knife on. I keep my eyes locked on the part of the stock that's against the fence.

I must be doing something right as I still have all 10 fingers and have never experienced kickback. That or I don't do enough woodworking!

[Thom2]

I've always stood to the right of the fence, and guide the wood with my right hand and push with the left. I know I'm not in the ultimate position in the event of kickback.

Actually, take a look at this link ....

http://www.newwoodworker.com/kickback.html

pay particular attention to the section "The mechanics of the kickout"

When I was young I experienced the very same thing Tom did and I now stand well to the right of the blade whenever possible. This puts me in a position where in the event of kickback, the wood will rotate against the fence, come up across the top of the blade to the left and theoretically clear me. IMO, standing to the left is like standing right smack in the path of a baseball bat.

If it's kickback you're concerned about, where you're standing now is the best place you can be IMO.

[cgallery]

If it's kickback you're concerned about, where you're standing now is the best place you can be IMO.

Well, the SawStop video has me more worried about severed fingers at this time. I have experienced kickback, though.

The piece of wood hit my hand (two or three stitches) and then rotated and hit the left side of my stomach (no stitches but there is a 4" scar--go figure), and then hit the wall behind me with such velocity that it put another 2" gash in the wall (paneling).

Had I just allowed the kickback to happen, I think I would have avoided the stomach hit. But I moved my body for more leverage and tried to stop it and discovered I'm no match for a 2-HP motor.

The cut was a bevel on the shorter end of a 9x12" piece, with bevel trapped under the blade. And the fence was toed IN (towards the blade) on my saw as delivered by about .008".

So a question I have is, if you turn the saw off, how much damage would the still-spinning blade cause to your hand?

My idea: They make those magnetic circuit breakers you put inline with a saw. If the power goes out, they open and prevent the saw from starting when power is restored (you have to "reset" the device). Would it be possible to add a safety feature to one of these that would attach to the arbor and sense skin contact (I think they use some sort of capacitance check) and just cut the power?

If your saw had a brake, you would further benefit from this sort of gizmo.

[cgallery]

Forget it. I just tried starting the saw and then turning it OFF and then pushing some white oak into it. No problem ripping 3-4" (plenty of momentum left to remove all your fingers).

[Stytooner]

The electric brakes like you see on motors is similar in fashion to brakes on a car. It slows the speed down evenly like applying the brakes would do.
The sawstop technology is more akin to jamming a stick through the front spoke of a moving bicycle. Very sudden stop. The extra momentum helps the blade disappear in an instant as well. It really is a good design at least in the way it works. Perhaps it can be done cheaer and we may see other makers come out with their own version eventually.

[BearPipes-1]

The SawStop marketing and advertising folks are doing a good job. My 4-year-old is mesmerized by the hot dog video, and insisted that we take the literature home from Woodcraft.

However, from a woodworking perspective, there's a thing that they can't emphasize that really should be taken into consideration: Every tablesaw injury is preventable if we're paying attention, using proper technique, and engaging the safety features available on, for example, the BT3k.

That's not to say that a tablesaw accident can't happen to anyone!

It does mean that one would normally have a miscue with a tool and blame oneself. But the SawStop message is: if you are injured by another tablesaw, the important thing is that your bad tablesaw hurt you; if you avoided major injury by using the SawStop saw, the important thing is that your good tablesaw saved you.

So whether the people they quote lost fingers or escaped with a nick, nobody confesses (and in some cases, it's evident from the quotes that the saw user doesn't know) what they were doing wrong.

And it's my contention that they were all doing something wrong, and that we'd learn a lot more if we knew what. That would be a less effective message for SawStop, however, and so I'm not going to hold my breath.

Mind you, if I were made of money, or were devoted to the idea that I should be able to let my mind and eyes wander in the shop, or if I were teaching others...I'd want a SawStop.

However, as I'm just as likely to bandsaw, lathe, biscuit-cut, route, or drill my fingers off...or have my unobservant children slam them in a door...I'll stick with my paid-for BT3100, with guard and splitter in place, push sticks galore, hold-downs and fingerboards out the yin-yang, and safety glasses+face shield in place. And I could still lose fingers, teeth, eyes, etc. Or get hit by a car. Or have a stroke.

This post brought to you by too much Mountain Dew. Guess who's going to stay out of the shop tonight!

[LCHIEN]

The electric brakes like you see on motors is similar in fashion to brakes on a car. It slows the speed down evenly like applying the brakes would do.
The sawstop technology is more akin to jamming a stick through the front spoke of a moving bicycle. Very sudden stop. The extra momentum helps the blade disappear in an instant as well. It really is a good design at least in the way it works. Perhaps it can be done cheaer and we may see other makers come out with their own version eventually.

Lee's analogy is good, but I think that the analogy of jamming a stick in a bicycle wheel spoke is actually far short of the real way the saw stop works. From the picture (and I admit I have not actually looked up and read the patent which should be simple matter to do, altho patents can be notoriously hard to read) and movie it appears that the mechanism not only jams the blade teeth but also uses the blade momentum to pull the blade down and below the table top.

A simple analysis of how fast things are happening will make the need for this clear. A typical TS blade turns at 3600 RPM (the BT even faster) and this is 60 Revs per second or 2400 teeth per second (for a 40-T blade) or somewhere around .4 milliseconds between teeth interval.
Human reaction speeds are around 250 milliseconds at best.
Assuming youre moving you hand at feed speeds of around 1 foot per second, what would happen?

If you allowed the blade to coast to a stop then it would take a second and you will have about cut off your hand in the 250 ms it took to react to the pain and blood.

If a blade brake was used then I estimate 250 ms best possible time still can cut off a whole hand.

So to work the sawstop mechanism has to sense the body capacitance (very fast, probably less than a few milliseconds) and then retract the blade faster than you hand is approaching. I imagine they jam a bar into the back of the blade which causes the blade momentum to pull it down very fast and some mechanical links to allow it to rotate downwards.
They have to jam the bar very fast . To prevent more than a surface wound it needs to pull away from the user in a time less than the time it takes for the user to move forward say 1/32", surely 1/16" worst case.
As we assumed we're moving a foot per second (normal feed speed) then we've got about 3 milliseconds to stop the blade. In this time about 7 or 8 teeth will nick you.

I think they have some electrically fired one-time cartridge to do this.
This may be similar to the cartridges used to fire air bags. The key to air bags is they've got to initiate and inflate a whole bag in less time than it takes for a body travelling 60 mph (88 ft/sec) to travel about 6" (or about 5 milliseconds). So the timing is about right and doable.

[Jeffrey Schronce]

It will be interesting to see when and if they produce the proposed contractor saw, how the features compare to the price. The price they cite is $800. If it is a very nice, high end contractor saw (which I believe it will be based upon the quality of the cabinet saw) then it would seem that the technology is not that expensive. $800 is certainly the high end of the contractor saw segment, however there are other contractor saws at this price point that don't have the SawStop safety feature. If the contractor saw has a riving knife and the instant stop technology, then $800 is a great deal in my opinion. The SawStop technology on a well built $800 contractor saw seems reasonable to me.

[jabe]

I had 1 kickback about 16 yrs ago my old tablesaw does not have any safety guards and I got careless, trying to make my last cut of the day. I was lucky not to get cut but got hit in the belly. I had a big bruse though. 20+ yrs ago my dad had a kickback accident, broke 3 ribs.
I saw many kickbacks while teaching woodshop and fortunately none of my students got cut, the board just flew off the TS. I would have bought the sawstop for the school shop but, it was not invented yet. I think all school shops should have SawStop installed on their TS now. It'll save the school districts alot of money, less liability and little or no injury to the students.
Couple of weeks ago a friend lost his index finger on his right hand due to a kickback. He admitted he did everything wrong no safety guard in place plus he was drinking. Years ago in the Kohala district of my island another friend's brother died from a kickback on the TS. He was elderly and short, the wood hit him in the chest, he had internal bleeding and it disrupted his heart beat. When they found him on the floor he was dead.
I know most of us cannot afford to buy the SawStop so just be careful, follow all safety rules and respect what the TS or any machine can do.
When you're tired, just turn off the machines and walk away.

[Stytooner]

Amen Abe.
IMO kickbacks are by far more deadly and unpredictable than simple amputations. If you get knocked in the head, there is no telling what might happen. Sometimes you get kickbacks with severed fingers to. It would be easy to get knocked out and bleed out with no one around or aware.
I have personally had a few minor kickbacks that hurt pretty good. I have had far more misses than hits.
(Warning! This next statement is something you would expect from the maker of a blade guard, but should not be taken as an ad, but pure fact so far. )
I haven't yet had anything close to an incident with a blade guard in place.

One odd thing that I would like to note. Both the Powermatic 2000 and the Sawstops riving knives leave a little something to be desired.
The PM's knife is far too tall to be able to leave on the saw all the time. They have said they are coming out with a smaller one that can be used without the blade guard much like the one on the SS.
These shorter knives are arced at the top and have really very little surface area. I just don't understand why they do that. More surface area is better IMO than less. Am I not getting it or are they not getting it?
I have mutated these now with Shark genes and one riving knife does it all.