Saw Stop

[Andrew Melamed]

Can I get some pictures of your guys hands if the need for the saw to be triggered happened. My shop teacher is saying that it won't work and youll still get hurt badly.....If your the one giving me the pics thank god you own a sawstop

[Damien Falgoust]

There are plenty of these over at the SawStop site.

[Andrew Melamed]

ok, ill take a look around. whats the price tag on one of them?

[Matt Moore]

www.sawstop.com (http://www.sawstop.com)

Just do a little searching and others have posted what they paid. The base price is $2999 plus accessories. I think that most end up spending between 3250-3750. Some of it depends on shipping/tax too.

Pricing (http://www.sawstop.com/products-cabinet-saw-pricing.htm)
Videos (http://www.sawstop.com/how-it-works-videos.htm)
Testimonials (http://www.sawstop.com/why-sawstop-testimonials.htm)

[Lars Thomas]

Andrew, your shop teacher needs to get his head out of the sand. You should be commended for venturing out to form your own opinion. Lars

[Cliff Rohrabacher]

I ain't a saw stop fan. But, you teacher is mistaken. Electricity travels at the speed of light. That's a lot faster than you can accidentially shove your finger through the blade.
It will shut down and pull down without leaving you needing more than a stitch or two - if that.

That is it will shut down unless something about the electrical system in the chip fails. Then it might take a bit longer or not shut down at all.

I prefer caution over trust every time. But that's just me.

[Michael Fross]

<snip>
I prefer caution over trust every time. But that's just me.
I agree Cliff, but having both is even better. I am a big fan of the saw and see a sawstop in my future sometime.

I just don't think people would get careless just because they believe the blade won't hurt them. I see it as an extra insurance policy just in case caution fails, as it sometimes does.

Michael

[Andrew Melamed]

If my school got one someone would try to test it and get hurt badly. If your using the saw normally and you push into the blade your fine. If you smack the blade maybe they would even try and lick it or something?......whatever they do it can hurt them...........sometimes i feel like the only one smart in woodshop:rolleyes:

[Mark Rios]

Lemmeseeeee...............licking the blade......hmmmmmmm...........

Do they LET kids that dumb in school these days?


:D :D :D

Andrew, I ( and probably your parents) hope you work WAAAAAAAAAAAAYYYYYYY away from these other kids.

[Doug Shepard]

Dont mean to derail the blade-licking theme going on here, but can someone shed some light on the SawStop zero clearance insert? I read a rather skimpy review in one of the current WW mags (forget which one at the moment). They mentioned something about the ZCI working through all the blade bevel settings. How do they do that? The review didnt elaborate. Is it just that the blade slot is just wide enough (and thus not truly a ZCI) to allow the blade tilts? Or is there some moveable section of the insert that slides open/close along with the tilt mechanism.

[Dan Drager]

Andrew, you miss the point. That is just it, they would "try" and test it by doing something stupid, But the worst they would get is a small knick in their finger / tongue / whatever. They simply could NOT hurt themselves. I have seen these saws demonstrated and have seen the hotdog "slammed" into the blade with a cut that a bandaid could handle. Far worse would be the cost to replace the brake and blade which could be a few hundred dollars.

[Ted Baca]

Doug the ZCI that SS uses is not a true ZCI. It has enough clearance to allow the blade at angle. As far I know there is no one making a ZCI for the SS. Possiblu one could be ordered from them that is blank. But is comes with the slot already cut when you buy the saw.

[Doug Shepard]

Doug the ZCI that SS uses is not a true ZCI. It has enough clearance to allow the blade at angle. As far I know there is no one making a ZCI for the SS. Possiblu one could be ordered from them that is blank. But is comes with the slot already cut when you buy the saw.

Thanks. I figured as much but the review left me wondering. I was picturing some slick new insert with one half sliding on a mini-dovetail way and expanding/contracting as the trunion got tilted. I'd be the first in line for one of those for my PM66 if such a beast existed.

[Joe Jensen]

Andrew, you miss the point. That is just it, they would "try" and test it by doing something stupid, But the worst they would get is a small knick in their finger / tongue / whatever. They simply could NOT hurt themselves. I have seen these saws demonstrated and have seen the hotdog "slammed" into the blade with a cut that a bandaid could handle. Far worse would be the cost to replace the brake and blade which could be a few hundred dollars.

The SawStop insert is "near" zero clearance. It is made of phenolic and the underside is heavily CNC machined to provide clearance for the arbor. One side is straight cut vertically, and the other side is cut at a 45 degree bevel so that you can run at angles. The blade clearance very tight. Tight enough, that the phenolic has chipped in a couple of places. Other than the very front of the blade, I'd say it's effectively a zero clearance insert.

If you need a true zero clearance insert, they sell an insert for cutting dados. It is made of wood and has no slot cut in it. Making your own would be pretty difficult..joe

[Kevin Groenke]

Andrew,

I wouldn't be surprised if a high school(?) student tried to hurt themselves with a SawStop, but that is NO excuse for your teacher to disregard this technology. IMHO your teacher is pretty much inviting a lawsuit by acknowledging the existence of this safety device and failing to upgrade the equipment. I run an educational shop and preordered SawStops 2 years before they were available because I thought it would be neglectful not to have them, but mostly because I don't want to see anybody get hurt. As far as I'm concerned your teacher isn't qualified for his job.

You'd have to try REALLY hard to hurt yourself. I saw a SawStop demo in which a 2' sausage was swung into the 3" high blade like a baseball bat. The result? A gash 3/8" - 1/2" deep, yeah, a nasty cut, but probably not an amputation. Just imagine what that have done on any other tablesaw.

As to the throatplate, the SS can get away with a single near-zero clearance throat plate because when it tilts it pivots on a point at table-top level. If I'm not mistaken Uni's (don't know about PM's or others) pivot at some point in space above the table top. This results in the necessity of a wider throat plate opening for beveled cuts because the blade intersects the tabletop at a different location. The other benefit of this pivot point location is that the rip fence scale remains accurate with the blade tilted...NICE.

The phenolic throatplates are effective 90% of the time, but they have gotten a bit chipped up over 2 years so we've made 0 clearance plates for perpendicular cutting only of very thin material. (-1/8").

Good Luck

[CPeter James]

Now that SS technology is available, any student that gets hurt on a conventional table saw might have grounds for a lawsuit against the school for not providing the safest equipment they could. It is an interesting point. Lawsuits have been won on lesser grounds.

CPeter

[Doug Shepard]

...As to the throatplate, the SS can get away with a single near-zero clearance throat plate because when it tilts it pivots on a point at table-top level. If I'm not mistaken Uni's (don't know about PM's or others) pivot at some point in space above the table top. This results in the necessity of a wider throat plate opening for beveled cuts because the blade intersects the tabletop at a different location. The other benefit of this pivot point location is that the rip fence scale remains accurate with the blade tilted...NICE.

The phenolic throatplates are effective 90% of the time, but they have gotten a bit chipped up over 2 years so we've made 0 clearance plates for perpendicular cutting only of very thin material. (-1/8").

Good Luck


Kevin - Thanks for clearing that up. The difference in pivot point explains it, though I'd think the slot would still have to be just a skosh wider than the blade even then - though not like on a conventional cabinet saw. Thanks for the PM too.

[Andrew Melamed]

too much for the budget......"if you follow saftey rules you wont get hurt"

[Mike Henderson]

too much for the budget......"if you follow saftey rules you wont get hurt"
And if you never make a mistake - one of those things humans do now and then.

Mike

[Matt Moore]

And if you never make a mistake - one of those things humans do now and then.
Mike

Exactly. I have had only once auto accident in my life when I was 19 and I figured it would never happen.... Well after 11 years it did. I try to replay it over to see where I went wrong and I can't even figure it out. It was not bad but I started to pull out in front of a van from a gas station and my front left hit their front right.

My point is that accidents happen and sometimes we can't even explain them.

Saftey is a good thing.

[Dan Clark]

too much for the budget......"if you follow saftey rules you wont get hurt"

If you follow the rules while driving your car, you won't get hurt. Riiiiight!

All the rules in the world don't cover the weird things that can happen. Someone bumps you at the wrong time. Wood hits an unseen knot or nail. Your foot slips unexpectedly. A car backfires just outside your house. You can do EVERYTHING right and still get hurt. That's the point...

Sawstop technology helps save your body parts even when you do everything right. I doubt that anyone in his/her right mind would ever stick their hand in a spinning SAWSTOP blade. Or take more risks just because they have a Sawstop saw. But when one of those bizarre little things happens in your life, it might save your fingers. To me, that's worth pretty much everything.

'Nuff said.

Dan.

[John Kain]

Ironic.

Note the thread same day posting:

http://www.sawmillcreek.org/showthread.php?t=46392

[Jim Bell]

Well Dan, mebe someone will invent a Belt Sand Stop....Then along with the SS you can have a :cool: BS! I think a set of belts and a harness worn by the operator and attatched to a large spring assembly to yank the saw operator swiftly away from the dangerous whirling blade in the event of an accident. Of course a helmet must be worn to prevent head injury as the force of avoidance will put most users through the shop wall. Of course this will lead to a need for :eek: Wall Stop. The good news is is no extra cost as these new items will be activated by the original Saw Stop mechanism. This device could also be used on any saw with proper rigging. Say a roofer properly equipped hits himself with a saw blade and WHAM............he is safely whisked away from danger and lands on the ground on his Fall Stop-Wall Stop.:D I feel safer already,
Jim

[Wayne Watling]

And if you never make a mistake - one of those things humans do now and then.
Mike

$4K so I can relax and fall to sleep on the job is not my idea of woodworking. My fingers are always at the other end of a push stick (of some description) when the blade is spinning. I plan out each cut and make that cut fully aware of where my arms, hands and fingers are in relation to the spinning blade and more importantly make sure there is little possibility that my limbs can make contact with the spinning blade should something go wrong - which can happen and could cause me to loose control to the point where my hand involuntarily comes into contact with the blade BUT this could happen on the SawStop and could equally result in a severed limb even with SawStop technology. Although my new slider should minimise the possibility of kickback dangers more so than a SawStop cabinet saw.

If you can't hold your attention squarely on what you are doing for that minimal period of time while cutting a piece of wood then you are not fit to drive that piece of equipment. Give it up and take up bowling or painting or whatever. On second thoughts leave bowling alone, plenty of damage could result from a waywood bowling ball.. hmm??? BallStop..???

Again, great saw and technology but for the individual hobbist woodworker, the decision to buy should be left with them.
Arn't you getting just a little sick to death of being told whats good for you by individuals/organizations who stand to gain millions of dollars from following their good advice.

W.

[Andrew Melamed]

something like that going to come with new underware?

[Dan Clark]

If they made a "Belt Stop", I'd buy one. There's nothing like looking down at the end of your middle finger from the first joint forward and noticing how it looks just like freshly ground hamburger. Or that joy of telling your wife to stop making a great dinner so that she can take you to the hospital to stop the bleeding (it took them two hours). Or the wonderous fun of coming home from the hospital and finding blood splattered on the bathroom walls, vanity top, sink and floor. Oooooh, and here's the good part. I get to wear a bandage for most of the next month while the finger heals. Oh yeah, that's really fun!

The mindless drivel that I constantly see about "following the rules", "using common sense", and "not working while tired" does nothing to explain away the constant stream of accidents that happen to people who ARE following the ruled, using common sense, and not working while tired. My hand accidentally brushed that belt for a second while I was examining a stud that I just finished sanding. One small slip and wham, it's blood city.

So I'm just extraordinarily happy that you are feeling safer. So you just have a really fine day.

Warmest regards,

Dan.

[John Kain]

$4K so I can relax and fall to sleep on the job is not my idea of woodworking. My fingers are always at the other end of a push stick (of some description) when the blade is spinning. I plan out each cut and make that cut fully aware of where my arms, hands and fingers are in relation to the spinning blade and more importantly make sure there is little possibility that my limbs can make contact with the spinning blade should something go wrong - which can happen and could cause me to loose control to the point where my hand involuntarily comes into contact with the blade BUT this could happen on the SawStop and could equally result in a severed limb even with SawStop technology. Although my new slider should minimise the possibility of kickback dangers more so than a SawStop cabinet saw.

If you can't hold your attention squarely on what you are doing for that minimal period of time while cutting a piece of wood then you are not fit to drive that piece of equipment. Give it up and take up bowling or painting or whatever. On second thoughts leave bowling alone, plenty of damage could result from a waywood bowling ball.. hmm??? BallStop..???

Again, great saw and technology but for the individual hobbist woodworker, the decision to buy should be left with them.
Arn't you getting just a little sick to death of being told whats good for you by individuals/organizations who stand to gain millions of dollars from following their good advice.

W.

Wayne, unless you are moving the piece through the machine at an unheard-of, ridiculas speed.........the sawstop stops and retracts within 3-5ms. That's milliseconds. Even at a very quick clip, that may leave you with a 4 to 7 mm cut (7mm at an unheard of rate). So fast, in fact, that your body won't even know what happened until the blade has been retracted. And that's moving way, way too fast through the blade.

To assume that everyone at all times will never make a mistake around a TS or any other power tool is hard to believe. A guy like me realizes that rarely mistakes happen. You can preach to me till high heaven about being a safe woodworker (and I am), but nothing beats an additional safety factor that saves fingers and potentially your livelihood.

[Andrew Melamed]

honelsty, i think that you though about something else.You need to mainely focus on where your hands and check the sanding job after the machine was off. If its not good you keep repeating.

[Wayne Watling]

Wayne, unless you are moving the piece through the machine at an unheard-of, ridiculas speed.........the sawstop stops and retracts within 3-5ms. That's milliseconds. Even at a very quick clip, that may leave you with a 4 to 7 mm cut (7mm at an unheard of rate). So fast, in fact, that your body won't even know what happened until the blade has been retracted. And that's moving way, way too fast through the blade.

To assume that everyone at all times will never make a mistake around a TS or any other power tool is hard to believe. A guy like me realizes that rarely mistakes happen. You can preach to me till high heaven about being a safe woodworker (and I am), but nothing beats an additional safety factor that saves fingers and potentially your livelihood.

John,

The reference was made to the following scenario; that in the unfortunate event you are the victim of a kickback and that leads to your body lurching forward with your hand landing squarely and solidly on to the spinning blade.

[Jim Bell]

Mindless drivel??? "following the rules" "paying attention" "not working when tired" or "using common sense". I suppose you were paying close attention and exercising common sense when you turned your finger into hamburger. It's a good thing you haden't a devil may care attitude or you could have sanded your hand off. Sounds to me like you may have issues that go beyond tablesaws.:)
Jim

[Jim Bell]

I forgot, for that hamburger thing we should have Blood Stop;)

[Mark Rios]

John,

The reference was made to the following scenario; that in the unfortunate event you are the victim of a kickback and that leads to your body lurching forward with your hand landing squarely and solidly on to the spinning blade.


Wayne, if I may....The tests and demos are not only done with a slow or normal feedrate. They affix the hotdog to a piece of wood and hit it into the spinning blade and other unusual ways as well. These tests and demos are done many, many times at shows on the weekends for many, many people to see.

From your posts, I'm not sure that you're aware of the ACTUAL speed in which the brake stops the blade. Perhaps you have never seen a demo in person or even on the Sawstop website.

There are pics, I believe somewhere here in the Creek, that someone has posted of an actual blade stuck in the brake block. Not only does the blade drop away into the table, effectively moving the blade away from the unfortunate person in your scenario, but the blade stops within the rotation of only 6 or 7 teeth. In the pics that I reference, four teeth are stuck in the block, one is just at the top of the block, and two more below the block appear to have scratches on them from the block beginning to contact the blade. With the blade stopping within the span of 7 teeth AND dropping down below the table, moving away from you, all in a matter of 5 milliseconds (or less), there is not very much SERIOUS damage that can be done. (The scratches on the two leading teeth were seen and inspected by the person who had received the block and blade from the demonstrator. The poster now has the blade and block on the wall of his shop as a reminder.)

May I direct you to the SawStop website and encourage you to watch the Sawstop chopsaw demo video. This, I believe, is a better example of the type of incident you may be referring to. The chop saw isn't a miter saw like we may use in our shops. Other than to just say that it's an industrial type of chop saw, it's a little difficult for me to try and describe the type of saw they use for the demo so, again, I encourage you to watch the demo for yourself, at least in the interest of fairness and to perhaps give you a little better understanding of the physics and mechanics involved.

On the other hand, your point of "being told whats good for you by individuals/organizations who stand to gain millions of dollars from following their good advice." is a seperate discussion entirely and may or may not have it's merits. However, the argument regarding the minimizing of injury with this tool is extremely difficult for ANYONE WHO HAS SEEN THE DEMOS IN PERSON or who have at least watched the video demos on the Sawstop website.

You might seek out a demonstration in your area, if perhaps there might be one or, again, at least go to the website and watch all the videos of the demos. Then, perhaps you may have a better understanding of the machine and obtain some more factual information to base your discussions on.


Chop saw video:

http://www.sawstop.com/products-future-products.htm

Main Video page:

http://www.sawstop.com/how-it-works-videos.htm

There are also some videos that do in fact play into the marketing of the saw, and you're right, some of it is a lot of marketing hype. But, if those bother you, then just watch the demos of the hotdog tests.

Give it a look Wayne. What could it hurt?

[Joe Jensen]

Here are some great independent test videos by a WW magazine.
http://www.woodmagazine.com/wood/story.jhtml?storyid=/templatedata/wood/story/data/sawstop_highspeed.xml&catref=wd5

Some realistic type accidents and fast hitting of the blade...joe


Wayne, if I may....The tests and demos are not only done with a slow or normal feedrate. They affix the hotdog to a piece of wood and hit it into the spinning blade and other unusual ways as well. These tests and demos are done many, many times at shows on the weekends for many, many people to see.

From your posts, I'm not sure that you're aware of the ACTUAL speed in which the brake stops the blade. Perhaps you have never seen a demo in person or even on the Sawstop website.

There are pics, I believe somewhere here in the Creek, that someone has posted of an actual blade stuck in the brake block. Not only does the blade drop away into the table, effectively moving the blade away from the unfortunate person in your scenario, but the blade stops within the rotation of only 6 or 7 teeth. In the pics that I reference, four teeth are stuck in the block, one is just at the top of the block, and two more below the block appear to have scratches on them from the block beginning to contact the blade. With the blade stopping within the span of 7 teeth AND dropping down below the table, moving away from you, all in a matter of 5 milliseconds (or less), there is not very much SERIOUS damage that can be done. (The scratches on the two leading teeth were seen and inspected by the person who had received the block and blade from the demonstrator. The poster now has the blade and block on the wall of his shop as a reminder.)

May I direct you to the SawStop website and encourage you to watch the Sawstop chopsaw demo video. This, I believe, is a better example of the type of incident you may be referring to. The chop saw isn't a miter saw like we may use in our shops. Other than to just say that it's an industrial type of chop saw, it's a little difficult for me to try and describe the type of saw they use for the demo so, again, I encourage you to watch the demo for yourself, at least in the interest of fairness and to perhaps give you a little better understanding of the physics and mechanics involved.

On the other hand, your point of "being told whats good for you by individuals/organizations who stand to gain millions of dollars from following their good advice." is a seperate discussion entirely and may or may not have it's merits. However, the argument regarding the minimizing of injury with this tool is extremely difficult for ANYONE WHO HAS SEEN THE DEMOS IN PERSON or who have at least watched the video demos on the Sawstop website.

You might seek out a demonstration in your area, if perhaps there might be one or, again, at least go to the website and watch all the videos of the demos. Then, perhaps you may have a better understanding of the machine and obtain some more factual information to base your discussions on.


Chop saw video:

http://www.sawstop.com/products-future-products.htm

Main Video page:

http://www.sawstop.com/how-it-works-videos.htm

There are also some videos that do in fact play into the marketing of the saw, and you're right, some of it is a lot of marketing hype. But, if those bother you, then just watch the demos of the hotdog tests.

Give it a look Wayne. What could it hurt?

[Mike Henderson]

I've been thinking about some of the objections expressed about the SawStop and I think perhaps they fall into two categories:

1. There's some investigation going on right now with the goal of improving the safety of table saws. I think perhaps some of the people who object to SawStop feel that there should be no safety regulations and that each person should buy as much safety as they choose to buy.

There are several problems with that approach. First, not every one gets to choose their tools. Students and people who work in a company using a table saw must use what's there. In each case, the purchaser of the equipment (or owner of the business) has an obligation to provide the safest work environment possible, consistent with cost constraints.

Second, even if you are the purchaser and the only user of the equipment, if you injure yourself, the cost of that injury will fall on others. If you have insurance, the cost of your injury must be paid by the other policy holders. If you injure yourself enough to be disabled, most people would have no choice but to accept disability payments or other public assistance, which costs all taxpayers.

And if you are disabled or die, society loses your productive capacity.

So society has a vested interest in requiring cost effective safety devices on tools and other things that might cause injury or death. The magic words are "cost effective" safety devices.

[added note] We are faced with a conundrum regarding safety features and their cost. As Jim and others have pointed out, some people have to save for a long time to be able to buy a $500 table saw. We certainly do not want to price table saws beyond the reach of those with modest means. But people with limited means are the most likely to require help from society if they get injured. They may not have insurance and it’s unlikely that they will have sufficient assets to support themselves without help from society if they become disabled. They’re the ones who should have the most safety features on their tools. This balancing act is difficult and will require input from all of us. There’s no right decision, just varying opinions about how much safety is enough. [end added note]

2. The inventor of the SawStop technology has acquired patents on the technology. If that technology becomes required on all table saws, the inventor stands to profit. I think perhaps some people object to the inventor profiting from the invention, especially if the technology is mandated by safety standards.

Our economic system is set up to encourage this. We grant patents to people who take risks and invent new things, but the patent has a limited life, 17 years. If someone objects to the SawStop inventor making money from his invention, just don't buy a saw with this technology for the next 17 years (assuming you're the only user of the saw). There are many good quality cabinet saws available today which will have a life in excess of 17 years. Just wait him out and buy a saw with that technology after the patent expires.

If there are other objections to the SawStop technology, I'd appreciate hearing what they are.

Mike

[Jim Bell]

Mike as I stated before the Saw Stop is a great idea. I have absolutely NO respect for the man who invented it. If you like it ..buy it. I agree there are places that should have these saws, however that is their decision, not yours or mine. As far as cost to society tablesaw accidents don't even register. You are obviously an educated man as your profile indicates. You claim to have 31 patents of your own. Do any of them have to do with the Saw Stop? If not, are you working on another idea that will be forthcoming? Just wondering. You remind me of a politician dead set on "helping" me. You are a wonderful craftsman. I admire your work, it shows attention to detail and finish. You know what tools cost and the wide range of quality that exists accross the board. Some guys save months or years to afford a $500.00 saw, then cringe at the thought of spending another $50.00 for a decent blade. There are a limited few who can afford the Saw Stop and a limited number of those who will actually see the need. In 6-12 months the market will be gone UNLESS legislation forces the issue. You know that. I recently attended a Saw Stop demo at the local Woodcraft. The crowd was 6 or 7 people for the first demo and 12 for the second. 5 of the 2nd demo were walking accross the parking lot and wondered what was going on. When the weiner struck they left. As advertised it (the weiner) was barely scratched. The tool and technology are fantastic. Too bad about the marketing blunder in the beginning. When the major tool makers wouldn't handle it the ONLY way to be profitable was legislation. They are still at it but time is not on their side as you well know. Personally I feel the ship has sailed. Too bad, under the proper circumstances the idea is a home run.
Jim

[Wilbur Pan]

...should something go wrong - which can happen and could cause me to loose control to the point where my hand involuntarily comes into contact with the blade BUT this could happen on the SawStop and could equally result in a severed limb even with SawStop technology.
Wayne, if you are going to make statements like this, you'll have to back them up with facts.

The SawStop system stops the blade in 5 ms. My wrist is 3 inches wide. If I was to deliberately chop off my hand on a SawStop, I would have to get those 3 inches through the blade in 5 ms.

If you do the math, you'd have to be hitting the blade at 34 mph to do this.

Now let's look at the scenario of getting hit in the stomach with a piece of wood from kickback and falling face first on the blade. For the average person, there's about 3 feet of vertical distance between your head and the surface of the tablesaw.

Suppose the force of the blow was such that you immediately passed out, and you had a dead fall onto the blade. If you drop an object, it takes 0.45 seconds to fall 3 feet. In this time, you'll accelerate to a speed of 4.4 m/s. This works out to 9.8 mph -- much slower than it would take to chop off my wrist on a SawStop. At that speed, you'll travel into the blade only 0.8 inches in the 5 ms it takes to stop the blade. That's still a bad cut, but much better than the alternative. Realize that this estimate of the depth of the cut is exaggerated. The blade will be braking as it slows down in that 5 ms, so that the amount of time that the blade is traveling at a speed sufficient to cut human tissue is even less.

Let's take an even more ridiculous scenario. Let's suspend a woodworker from the ceiling of his shop and drop him directly on a SawStop. In order to chop off a hand at the wrist, he'll have to be going 34 mph when he hits the blade. In a dead fall, it will take him 1.5 seconds of free fall before he reaches that velocity. A dropped object will fall 39 feet in 1.5 seconds. This means that you would have to drop a woodworker from a height of 39 feet onto a SawStop before he develops the velocity needed to chop off a hand at the wrist.

(This is, of course, assuming Earth gravity. Someone else can do the math for woodworkers on Jupiter. :) )

[Kevin Groenke]

Jim,

You, of course, are entitled to your own opinion which is reasonable and understandable. I'm glad to see that you recognize the value that this development to equipment users who do not necessarily have a choice as to which particular brand/model of machine they use (students, employees).

But I have to to disagree with:
<qoute>
In 6-12 months the market will be gone UNLESS legislation forces the issue.
<qoute>

As discusssion here lately indicates, the buzz about and interest in this machine has continued to increase for the 2+ years since it was initially released. As the number of machines in use has increased and woodworkers have been able to see, hear about and use the saws, interest has grown and sales have probably increased. A growing retail network makes the machine easier and less "risky" to buy sight unseen. All indications are that SS not only added a valuable safety feature previously unavailable, but the designed a generally better saw than was previously available in the marketplace at it's price point.

Just on the Creek, how many folks who have swapped their 66's and Uni's for SS's in the past few weeks? How many have upgraded from their crapsmans and cabinet saws? More importantly, HOW MANY HAVEN'T? Many more than 6-12 months worth I think.

We know that SS is working on bandsaws and chopsaws too, so it does'nt appear that they have specific plans to be a "one trick pony".

It seems that the free market is alive and well in the power tool industry. Somebody built a better mousetrap. Mousetrap users are buying them, thinking about buying them, and replacing their old moustraps that had a tendency to SNAP on their fingers.


Who knows what will happen with the legislation, not to mention the effects of litigation which reportedly has already begun and is quite likely to increase (I got hurt at work 'cause they didn't have this safer machine = $$$$). But I don't think any of that matters anymore.

Does anybody believe that other manufactures don't have product development teams working on systems for stopping sawblades? If they don't, they're very ineffective companies (oh, we already knew that).

Would that be the case if Steven Gass hadn't been committed to his idea and gone WAY out on a limb to see it come to fruition? I don't think so. Thanks Steve.

DISCLAIMER
I have no financial interest in SawStop LLC, though I wish I did.
I have no relation with SawStop LLC or it's principles, other than that of satisfied customer and occasional professional aquaintence.

[Mike Henderson]

You claim to have 31 patents of your own. Do any of them have to do with the Saw Stop? If not, are you working on another idea that will be forthcoming? Jim
Nope - no work at all on anything that can be patented - just woodwork. I'm retired. All of my existing patents are communications related. The list of my patents is here (http://members.cox.net/michael.henderson/Patents.htm). You can verify them by going to www.uspto.gov (http://www.uspto.gov) and searching on the patent number. It will be extremely boring reading.

I have nothing to do with SawStop and do not know the inventor or anyone associated with the company or the invention.

Mike

[Dan Clark]

Mindless drivel??? "following the rules" "paying attention" "not working when tired" or "using common sense". I suppose you were paying close attention and exercising common sense when you turned your finger into hamburger. It's a good thing you haden't a devil may care attitude or you could have sanded your hand off. Sounds to me like you may have issues that go beyond tablesaws.:)
Jim

It's mindless drivel when the message is, "Just follow the rules, Etc and you won't have an accident." That's a crock. It's obvious you have no clue about how careful I am; you are making some massive, unwarrented assumptions.

An accident can occur no matter how careful you are!!! When that happens, all the cute little sayings about following the rules become meaningless. Your jokes about "belt stop" are in particularly poor taste!

What I didn't mention was that the belt sander was spinning down when the accident occured. OBVIOUSLY, I should have waited another few seconds. (I did that the other forty or so times I used it last Sunday.) OTOH, if the sander had a brake on it, this accident would not have happened.

Sawstop technology, riving knives, belt sander brakes, and a whole host of other safety improvements can be made to tools that will help save body parts when the an accident occurs. I'm a careful driver even though my Audi has four wheel drive, traction control, anti-lock brakes and an air bag. Having safety features on my tools won't make me any less careful.

If you feel the need to take lots of risks, it's a free country; have at it. Just don't insult me if I choose not to.

Dan.

[Andrew Melamed]

thats not the table saws fault. its the guy working while tired.

[Mark Rios]

Reading through this and other threads about the Sawstop and it's technology I had some thoughts come up in my head (I know, I know...scary).

HOW were airbags able to be invented? Anti-lock brakes? How was the Sawstop technology developed?......Computer processor speed. As we make processors faster and faster they will enable us to do more and more. I'm sure that Mike H., for one, can attest to that.

In 50 years society may see the Sawstop table saw as a crude invention compared to the safety features on power tools or even new/different ways of cutting and using the tools we have in our shops. Continuing the auto airbag analogy, airbags went from a (relatively) barely controlled explosion to a sixth or seventh generation that now senses the force of the impact/collision, senses the weight and size of the person and the distance that the person is to the airbag and adjusts the explosion accordingly. Modern technology at work.

This is just a big and radical step forward in power tool technology. It will get refined and improved upon as well as other safety devices and concepts that we don't think of today.

I wonder if maybe some folks just are having a hard time adjusting to the advances in the technology of our beloved tablesaws (and other shop tools) like some of our parents had/have trouble adjusting to computers.

Time marches on and so does technology.

Just my thoughts.

[Anthony Anderson]

Jim, I am not going to waste my time with a reply to your pointless rant. Other than this, of course. I am just sitting here shaking my head. I hope you are just doing this to get a reaction, and I also hope that you are not really this narrow minded, or use this pseudo logic. :p :p :p . Regards, Bill


I forgot, for that hamburger thing we should have Blood Stop;)

[Jim Becker]

Folks...play nice. I really don't want to have to start editing/deleting posts for personal attacks, especially on Thanksgiving. Thanks in advance for your coopertation.

Jim
SMC Moderator

[Mark Rios]

Jim, I am not going to waste my time with a reply to your pointless rant. Other than this, of course. I am just sitting here shaking my head. I hope you are just doing this to get a reaction, and I also hope that you are not really this narrow minded, or use this pseudo logic. :p :p :p . Regards, Bill


I"m not going to speak for Jim but I took it as a tongue-in-cheek, maybe sarcastic type of comment. He may have meant it diferently but I didn't take it that way.

Quite frankly, as an EMT, my mind went in all kinds of directions when I read that post. Hmmmmm.................:D :D :D

[Wayne Watling]

Wayne, if I may....The tests and demos are not only done with a slow or normal feedrate. They affix the hotdog to a piece of wood and hit it into the spinning blade and other unusual ways as well. These tests and demos are done many, many times at shows on the weekends for many, many people to see.
...



Mark,

I have viewed the video and watched the sausage as it was pushed into the blade, I dont think anyone has any problem accepting that it works under those controlled conditions. I think on every post I've made I have added that the technology is very good for what it is, my main gripe is that I would not like it forced onto the hobbist woodworker community. The hobbist woodworker working by him/her self is not endangering anyone other than him/her self so the decision to purchase this expensive safety device should be left with them. Its not like a motor vehicle airbag scenario where you will have passengers in the car with you.

I'd be very interested in a video of a pork leg slamming onto the blade from above (visually a little humerous I know) but this scenario would emulate an operators hand involuntarily slapping down hard (and at speed) onto the blade which could occur if you get hit hard by a piece of wood and react uncontrollably.
Due to the downward movement of the limb onto the blade, in the same direction that the blade is pulled away down under the table, the limb would be in contact with the blade for a longer period than if it was simply pushed into the blade straight on. You also get more limb movement through the spinning blade (because of the speed and direction of limb movement) than you would with the controlled promotional sausage demonstration.

Is there such a video or has this scenario been tested and documented by SawStop?

[Mark Rios]

Mark,

I have viewed the video and watched the sausage as it was pushed into the blade, I dont think anyone has any problem accepting that it works under those controlled conditions. I think on every post I've made I have added that the technology is very good for what it is, my main gripe is that I would not like it forced onto the hobbist woodworker community. The hobbist woodworker working by him/her self is not endangering anyone other than him/her self so the decision to purchase this expensive safety device should be left with them. Its not like a motor vehicle airbag scenario where you will have passengers in the car with you.

I'd be very interested in a video of a pork leg slamming onto the blade from above (visually a little humerous I know) but this scenario would emulate an operators hand involuntarily slapping down hard (and at speed) onto the blade which could occur if you get hit hard by a piece of wood and react uncontrollably.
Due to the downward movement of the limb onto the blade, in the same direction that the blade is pulled away down under the table, the limb would be in contact with the blade for a longer period than if it was simply pushed into the blade straight on. You also get more limb movement through the spinning blade (because of the speed and direction of limb movement) than you would with the controlled promotional sausage demonstration.

Is there such a video or has this scenario been tested and documented by SawStop?


I"m sorry Wayne but I have to disagree. Once the flesh comes in contact with the blade the 5 milliseconds that it takes for the blade to drop below the table is MUCH faster than the speed that the limb is moving. Wilburs math is pretty sound up in post number 36.

However, I too would like to see the pork leg demo. In fact, I mentioned to another member in a PM that I'm going to look for a demo in here in Central CA and put up the money for the blade and cart (I'll have to bring my own pork leg I imagine :D ) in order to do that specific test.

Math and physics are a couple of hobbies of mine at the junior college two blocks away from me and I am an EMT as well. Please understand, I, nor Sawstop, nor most anyone else, is claiming that ALL injury will be totally eliminated. But the difference will absolutely be a "minor" injury, perhaps requiring stitches, rather than a debilitating one or an amputation. The science behind the technology is very sound.

Your other, separate point of "the technology being forced on us" is, again, a point that may or may not have its merits. However, I don't feel that this is the place to discuss that sort of topic here. I respect your feelings on that issue but I won't argue it.

[Randal Stevenson]

I ain't a saw stop fan. But, you teacher is mistaken. Electricity travels at the speed of light. That's a lot faster than you can accidentially shove your finger through the blade.



Fingers travel at the speed of Oh (censored)!;)

[Wilbur Pan]

I'd be very interested in a video of a pork leg slamming onto the blade from above (visually a little humerous I know) but this scenario would emulate an operators hand involuntarily slapping down hard (and at speed) onto the blade which could occur if you get hit hard by a piece of wood and react uncontrollably.
Due to the downward movement of the limb onto the blade, in the same direction that the blade is pulled away down under the table, the limb would be in contact with the blade for a longer period than if it was simply pushed into the blade straight on. You also get more limb movement through the spinning blade (because of the speed and direction of limb movement) than you would with the controlled promotional sausage demonstration.

Wayne,

In case you missed it, see my post above. But to summarize:

Dead fall onto the SawStop blade from three feet up means you hit that blade at 4.4 m/s. In the 5 ms that the blade comes to a halt, that's a cut of 0.8 inches. This is likely an overestimation of a real life collision because it assumes that the blade cuts equally efficiently from the beginning to the end of that 5 ms period. Because of braking and the dropping of the blade under the table surface, the effective contact time will be less. In any case, it's much better than doing a dead fall onto a Unisaw.

[Wayne Watling]

I"m sorry Wayne but I have to disagree. Once the flesh comes in contact with the blade the 5 milliseconds that it takes for the blade to drop below the table is MUCH faster than the speed that the limb is moving. Wilburs math is pretty sound up in post number 36.

However, I too would like to see the pork leg demo. In fact, I mentioned to another member in a PM that I'm going to look for a demo in here in Central CA and put up the money for the blade and cart (I'll have to bring my own pork leg I imagine :D ) in order to do that specific test.

Math and physics are a couple of hobbies of mine at the junior college two blocks away from me and I am an EMT as well. Please understand, I, nor Sawstop, nor most anyone else, is claiming that ALL injury will be totally eliminated. But the difference will absolutely be a "minor" injury, perhaps requiring stitches, rather than a debilitating one or an amputation. The science behind the technology is very sound.

Your other, separate point of "the technology being forced on us" is, again, a point that may or may not have its merits. However, I don't feel that this is the place to discuss that sort of topic here. I respect your feelings on that issue but I won't argue it.

Mark,

Firstly I would strongly advise you not to do this testing yourself, it sounds extremely dangerous to me. To test it correctly you would have to slam a full leg of pork down onto the spinning blade with maximum possible force. The pork leg would have to be carefully chosen to represent the consistency of living flesh, bone and cartilage, which is very different to a rubbery bouncy sausage consistency. Should the SawStop unit fail, it could result in a horrific injury to your hand if it becomes drawn into the blade because of the bone and cartilage material catching in the blade. This is a test I would expect the SawStop company to carry out using mechanical equipment in an otherwise empty room.

Take care,
Wayne

[Mark Rios]

Mark,

Firstly I would strongly advise you not to do this testing yourself, it sounds extremely dangerous to me. To test it correctly you would have to slam a full leg of pork down onto the spinning blade with maximum possible force. The pork leg would have to be carefully chosen to represent the consistency of living flesh, bone and cartilage, which is very different to a rubbery bouncy sausage consistency. Should the SawStop unit fail, it could result in a horrific injury to your hand if it becomes drawn into the blade because of the bone and cartilage material catching in the blade. This is a test I would expect the SawStop company to carry out using mechanical equipment in an otherwise empty room.

Take care,
Wayne


While not discounting your above admonishment in any way, you apparently have chosen to ingnore ALL of the really relevent info provided by both Wilbur and myself as well as by all and anyone who has thus far posted in the many different forums, including Sawstop's information. I'll refrain from chatting with you further on this subject as it simply will go nowhere productive.

Wayne, slamming "a full leg of pork down onto the spinning blade with maximum possible force" is just silly and unrealistic.

[Wayne Watling]

While not discounting your above admonishment in any way, you apparently have chosen to ingnore ALL of the really relevent info provided by both Wilbur and myself as well as by all and anyone who has thus far posted in the many different forums, including Sawstop's information. I'll refrain from chatting with you further on this subject as it simply will go nowhere productive.

Wayne, slamming "a full leg of pork down onto the spinning blade with maximum possible force" is just silly and unrealistic.

As you wish, but I have NOT chosen to ignore anyone. I read Wilburs material but he failed to take into account the true maximum force of an uncontrolled limb smashing onto the blade. When looking at accidents like this you should look at worst case scenarios and that is NOT a *bouncy* sausage or a human dropping under the force of gravity and contacting the spinning blade.
I'm sorry you took offence at what I had to say it was not meant to cause offence in any way. Thank you for your otherwise welcome contribution.

Wayne

[Art Mulder]

I'd be very interested in a video of a pork leg slamming onto the blade from above
...
Is there such a video or has this scenario been tested and documented by SawStop?

Yes it has. I'm surprised that no one has mentioned this. Even better, it was by a third party, not SawStop.

Go to woodmagazine.com (http://www.woodmagazine.com), click on the "free woodworking videos" link, and then click on the link for Saw stop.

They have a video there where they SLAM a hotdog down onto the top of a sawstop. The cut is less than 1/4" deep. Stitches? maybe. Amputation? No.

...art

[Wayne Watling]

Yes it has. I'm surprised that no one has mentioned this. Even better, it was by a third party, not SawStop.
Go to woodmagazine.com (http://www.woodmagazine.com), click on the "free woodworking videos" link, and then click on the link for Saw stop.
They have a video there where they SLAM a hotdog down onto the top of a sawstop. The cut is less than 1/4" deep. Stitches? maybe. Amputation? No.
...art

Art,

I've watched this video and like you say its a video of a rubbery bouncy sausage stiking the spinning blade (and riving knife). In my view consistency is important as well as speed and force of the object used, and that is why a pork leg is being suggested as more suitable for the test.

Regards,
Wayne

[Matt Moore]

I'd be very interested in a video of a pork leg slamming onto the blade from above (visually a little humerous I know) but this scenario would emulate an operators hand involuntarily slapping down hard (and at speed) onto the blade which could occur if you get hit hard by a piece of wood and react uncontrollably.
Due to the downward movement of the limb onto the blade, in the same direction that the blade is pulled away down under the table, the limb would be in contact with the blade for a longer period than if it was simply pushed into the blade straight on. You also get more limb movement through the spinning blade (because of the speed and direction of limb movement) than you would with the controlled promotional sausage demonstration.

Is there such a video or has this scenario been tested and documented by SawStop?

Take a look at the chop saw video. I think it represents a similar scenario to what you are requesting.
http://www.sawstop.com/products-prototypes.htm

[Jim Bell]

Hi guys, well I had a great turkey day and hope you all did also. Dan if an apology is necessary you have one. I like to have fun and at times get carried away. I hope your finger heals well. It is probably a lot like road rash which is slow healing and wrather painful. It always seems to be the one that gets bumped. I would like to see brakes on most if not all of my power tools. I have a Dewalt c/m slider that has an excellent brake as do all of my cordless screw and drill drivers. Why not have one on my Unisaw? Why not on my circular saw? (Milwaukee) My shop is equipped with some of the best tools America has to offer. I agree most tools can and should be safer. At the same time I have to use them responsibly. I also accept whatever risk the tool itself brings to the table as well as my potential mistake or misuse. Then there is the mystery within the materials themselves. Our job/hobby is loaded with tools that can hurt or maim in a split second. My problem with all this is I simply want the right to choose for myself. Again if I offended anyone my apologies. Most of what I did was in fun. I mean wall stop fall stop. try to picture that in your mind. I was laughing so hard when I typed that last night my wife thought a heart attack was possible. :D
Jim

[Wayne Watling]

Take a look at the chop saw video. I think it represents a similar scenario to what you are requesting.
http://www.sawstop.com/products-prototypes.htm

No, thats just the same as all the other videos, its a rubbery sausage hitting the spinning blade.

[Wilbur Pan]

As you wish, but I have NOT chosen to ignore anyone. I read Wilburs material but he failed to take into account the true maximum force of an uncontrolled limb smashing onto the blade.
I'm sorry, but you are flat out wrong here. I showed that a limb would have to be moving 34 mph in order to produce a cut 3" deep, enough to sever a hand at the wrist, within the 5 ms that the SawStop would need to brake the blade. This is basic Newtonian physics. The fact that you are talking about force when the only issue here is velocity shows that you are misunderstanding what factors really come into play here.

Again, this is assuming that the SawStop is cutting efficiently from the beginning to the end of that 5 ms period, which is highly unlikely, as the blade is decelerating and dropping down into the saw at the same time. Other factors, such as the increased resistance that bone would offer only serve to increase the calculated speed necessary to sever a hand at the wrist in that 5 ms period. So the scenario I outlined is the worst case scenario.

Furthermore, one key aspect of the SawStop mechanism is that the blade drops below the tabletop in that 5 ms time span. According to the SawStop website, the maximum depth of cut for the SawStop is 3 1/8inches. The safety mechanism drops the blade 3 1/8 inches in 5 ms, which works out to 35.5 mph. If you add that to the velocity of your limb hitting the blade, then your limb would have to be traveling close to 70 mph to maintain contact with the blade as it drops below the table so you can chop your hand off.

I am not arguing that it is impossible for a limb to be severed on a SawStop. I am simply pointing out the speeds that that limb would have to travel at in order to be severed in a 5 ms time span.

If you can show that the uncontrolled limb movement you are thinking of gets up to at least 34 mph (and preferably 70 mph), please do so. But yammering about "the true maximum force of an uncontrolled limb smashing onto the blade" without numbers or facts gets you nowhere.

Again, I've already shown that the likely scenario (kickback hits woodworker, renders him unconscious, and he falls flat on the blade) will not result in a body part hitting the blade at anywhere near these speeds.

I can think of one deliberate movement that might be fast enough to meet this criteria: the hand of a Major League pitcher throwing a fastball might move this fast. But I have a hard time picturing Greg Maddux being hit by a piece of wood from a kickback and then launching into a windup motion, slamming his hand on the blade.

[Joe Jensen]

Wayne, did you take a few minutes to view the videos I posted on a link earlier in this thread? Wood Magazine did independent tests of several scenarios to simulate dragging a hand back into the blade after a cut, and a fast movement into the blade like in a kickback. In the scenario you describe, I'd like to see a comparison of the Sawstop running, and a standard saw not running. I suspect some serious damage even with a stationary blade with that much mass and momentum. Here is the link again for your convenience.
http://www.woodmagazine.com/wood/story.jhtml?storyid=/templatedata/wood/story/data/sawstop_highspeed.xml&catref=wd5



Mark,

I have viewed the video and watched the sausage as it was pushed into the blade, I dont think anyone has any problem accepting that it works under those controlled conditions. I think on every post I've made I have added that the technology is very good for what it is, my main gripe is that I would not like it forced onto the hobbist woodworker community. The hobbist woodworker working by him/her self is not endangering anyone other than him/her self so the decision to purchase this expensive safety device should be left with them. Its not like a motor vehicle airbag scenario where you will have passengers in the car with you.

I'd be very interested in a video of a pork leg slamming onto the blade from above (visually a little humerous I know) but this scenario would emulate an operators hand involuntarily slapping down hard (and at speed) onto the blade which could occur if you get hit hard by a piece of wood and react uncontrollably.
Due to the downward movement of the limb onto the blade, in the same direction that the blade is pulled away down under the table, the limb would be in contact with the blade for a longer period than if it was simply pushed into the blade straight on. You also get more limb movement through the spinning blade (because of the speed and direction of limb movement) than you would with the controlled promotional sausage demonstration.

Is there such a video or has this scenario been tested and documented by SawStop?

[Art Mulder]

I've watched this video and like you say its a video of a rubbery bouncy sausage stiking the spinning blade (and riving knife). In my view consistency is important as well as speed and force of the object used, and that is why a pork leg is being suggested as more suitable for the test.

Wayne, I don't follow your reasoning at all. Please explain what I'm missing. What does the 'consistency' of the flesh have to do with how quickly the sawstop blade stops and is retracted?

Seems to me that the hot dog, since it has no bone backing it up, and is basically a meat "paste" inside a tube, would actually show more damage than something more like my forearm.

...art (who finds all this arguing just a bit puzzling. I don't have a sawstop, but it is something I would look at very hard if I was in the market.)

[Wayne Watling]

I'm sorry, but you are flat out wrong here. I showed that a limb would have to be moving 34 mph in order to produce a cut 3" deep, enough to sever a hand at the wrist, within the 5 ms that the SawStop would need to brake the blade. This is basic Newtonian physics. The fact that you are talking about force when the only issue here is velocity shows that you are misunderstanding what factors really come into play here.

Again, this is assuming that the SawStop is cutting efficiently from the beginning to the end of that 5 ms period, which is highly unlikely, as the blade is decelerating and dropping down into the saw at the same time. Other factors, such as the increased resistance that bone would offer only serve to increase the calculated speed necessary to sever a hand at the wrist in that 5 ms period. So the scenario I outlined is the worst case scenario.

Furthermore, one key aspect of the SawStop mechanism is that the blade drops below the tabletop in that 5 ms time span. According to the SawStop website, the maximum depth of cut for the SawStop is 3 1/8inches. The safety mechanism drops the blade 3 1/8 inches in 5 ms, which works out to 35.5 mph. If you add that to the velocity of your limb hitting the blade, then your limb would have to be traveling close to 70 mph to maintain contact with the blade as it drops below the table so you can chop your hand off.

I am not arguing that it is impossible for a limb to be severed on a SawStop. I am simply pointing out the speeds that that limb would have to travel at in order to be severed in a 5 ms time span.

If you can show that the uncontrolled limb movement you are thinking of gets up to at least 34 mph (and preferably 70 mph), please do so. But yammering about "the true maximum force of an uncontrolled limb smashing onto the blade" without numbers or facts gets you nowhere.

Again, I've already shown that the likely scenario (kickback hits woodworker, renders him unconscious, and he falls flat on the blade) will not result in a body part hitting the blade at anywhere near these speeds.

I can think of one deliberate movement that might be fast enough to meet this criteria: the hand of a Major League pitcher throwing a fastball might move this fast. But I have a hard time picturing Greg Maddux being hit by a piece of wood from a kickback and then launching into a windup motion, slamming his hand on the blade.

Wilbur,

Thanks for responding. I'll state up front, I'm no math/physics expert but I can follow on to some degree with what you present. Based on what you presented it does seem that if a hand slapped down onto a blade with the arm moving somewhere between 34 and 70 mph a finger could be severed which is what I said in my original post (I may have used the word 'limb' but I was refering to a finger, I'm not sure if a finger is officially a limb or not). Another variable I was uncertain about was the realistic maximum possible speed an arm could come down onto the blade given a massive uncontrolled reaction by the operator from a kickback. I think you gave a good visual with the pitcher, but I agree that sounds unrealistic but if we halve the difference that then perhap we might be getting close.

W.

[Chris Barton]

Boy, I sure am glad that the mention of Sawstop still fills a thread and that there are so many folks with less than 40 posts willing to keep the pot stired. I thought aliens had taken over...

[Wayne Watling]

Wayne, I don't follow your reasoning at all. Please explain what I'm missing. What does the 'consistency' of the flesh have to do with how quickly the sawstop blade stops and is retracted?

Seems to me that the hot dog, since it has no bone backing it up, and is basically a meat "paste" inside a tube, would actually show more damage than something more like my forearm.

...art (who finds all this arguing just a bit puzzling. I don't have a sawstop, but it is something I would look at very hard if I was in the market.)

I raised this point because I have only ever seen a sausage used in the test and with an object of that consistency and flexibility I would think there would be some deflection from the saw blade (being ever so slight). At these speeds it all counts.

W.

[Joe Jensen]

I raised this point because I have only ever seen a sausage used in the test and with an object of that consistency and flexibility I would think there would be some deflection from the saw blade (being ever so slight). At these speeds it all counts.

W.

Wayne, did you take a minute to review the multiple videos taken by Wood Magazine and posted on their website. I think they simulate more realistic situations than the SawStop posted video. I posted the link twice above for your convenience...joe

[Wilbur Pan]

Wilbur,

Thanks for responding. I'll state up front, I'm no math/physics expert but I can follow on to some degree with what you present. Based on what you presented it does seem that if a hand slapped down onto a blade with the arm moving somewhere between 34 and 70 mph a finger could be severed which is what I said in my original post (I may have used the word 'limb' but I was refering to a finger, I'm not sure if a finger is officially a limb or not). Another variable I was uncertain about was the realistic maximum possible speed an arm could come down onto the blade given a massive uncontrolled reaction by the operator from a kickback. I think you gave a good visual with the pitcher, but I agree that sounds unrealistic but if we halve the difference that then perhap we might be getting close.


Wayne,

It's ironic that your lack of recall as to what you said in your original post involves a post where you state how careful you are to be aware of your activity. Here's your original post, to refresh your memory:


$4K so I can relax and fall to sleep on the job is not my idea of woodworking. My fingers are always at the other end of a push stick (of some description) when the blade is spinning. I plan out each cut and make that cut fully aware of where my arms, hands and fingers are in relation to the spinning blade and more importantly make sure there is little possibility that my limbs can make contact with the spinning blade should something go wrong - which can happen and could cause me to loose control to the point where my hand involuntarily comes into contact with the blade BUT this could happen on the SawStop and could equally result in a severed limb even with SawStop technology....

I am glad that you are more careful when working with a tablesaw than you are when making assertions in a internet forum. The definition of a limb is "a leg or arm of a human being", according to my dictionary.

Also, unless you can either point out a mistake in my calculations or come up with some of your own, there's no "halving the difference". You asserted that one could sever a limb on a SawStop if there was involuntary contact with the blade. I've shown that to sever a limb on a SawStop you need to be hitting the blade at a speed of at least 34 mph. This is a worst case scenario: it assumes that the only thing that the SawStop is doing is stopping the blade, it assumes that the blade works completely efficiently during the braking time, and it ignores the fact that the blade also drops down into the table, which provides an additional safety factor. In fact, my model and calculations are actually slanted in your favor, and they still prove your assertion wrong. In fact, you really need to be hitting the blade at speeds much faster than 34 mph to do that amount of damage, while involuntary movements don't make your body move nearly that fast.

I'm not in the machinery design business, but if I were to figure out what I needed to make a tablesaw stop a blade fast enough to keep damage from happening in cast of contact, these are exactly the calculations I would go through to figure out how fast I need to stop that blade. I'm sure that the SawStop designers went through a similar process before they would bring such a device to market.

What you should do, assuming that you can't come up with a set of calculations to show that it is possible to sever a limb at low velocity in 5 ms, is retract your original statement. You can say that you don't like the SawStop for political reasons. But as far as I can see, you can't say that it won't work as designed.