sawstop running

Leon wrote:

> I believe in the real world you hand is moving no where near 4.5 MPH
during
> any operation around a TS unless you are jerking you hand back.

I don't know 4.5MPH isn't all that fast -- about 6.6 feet per second.
Slip/trip and fall while pushing a big 8 or 12 quarter boar and you
could probably hit 6.6 fps into the blade. Heck a 6'6" guy can fall
and hit his head be on the ground in less than a second -- that's an
average of over 6fps. Little g is 9.8m/s^2 --- a gravity drop will
give you about 27 fps after one second. It's not the intended
operations around the saw that you have to worry about.

hex
-30-

On Sun, 09 Jan 2005 14:57:29 -0700, [email protected] wrote:

>On Sun, 9 Jan 2005 15:29:41 -0500, "Mike Marlow"
><[email protected]> wrote:
>
>
>
>>6 1/2 feet per second? Man, I can't feed wood that fast on my table saw. I
>>need a better table saw.
>
>
>that's not the speed of the wood- it's the speed of your hand when it
>slips off of the wood and you lean in to catch yourself.

A superb visual example of that is watching the video clip used in
Norm's safety speech on NYW the last several years. As he's feeding a
piece through the router table (quite nicely held down with feather
boards, by the way) his forward hand slips. I cringe every time I see
it, even though there's no danger, as I've had my hand slip on a piece
of work before, too, and I can well imagine that happening around a
cutting implement.

By the way, I was taught long ago never to have one's hands over the
rotating cutter head on a jointer when feeding stock through it for
that very reason (the stock shooting out, not the hands slipping), yet
I see virtually every TV wooddorker violating that every single time
they joint.


- -
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net

On 11 Jan 2005 15:00:31 -0500, dwright <[email protected]> wrote:
> Other SawStop reports are starting to trickle in. Search for posts by
> "Vanguard" @ woodnet.net and "Dave Wright #2" (me) @ sawmillcreek.org.
> I also put up a detailed review with editing help from LRod @
> woodcentral.com.

I see I can only "click here to pre-order" on the website, though.

In news:Duane Bozarth <[email protected]> typed:
> But still doesn't answer the question of whether it can detect the
> condition of hand on board into the saw...which is the only case I've
> ever even come close to finding myself in. I've never had any concern
> of just putting my hand into the blade by itself...

www.sawstop.com has all the video you will ever need to see...
--
Ted Harris
http://www.tedharris.com

On Fri, 14 Jan 2005 23:49:06 GMT, patrick conroy <[email protected]> wrote:
>
> "dwright" <[email protected]> wrote in
> message news:[email protected]...
>
>> At some point someone's got to try hacking
>> the cartridge.
>
> Kind'a like buying a "chip" to gain 30HP on your car, I suppose.

You do know that that is how performance mods are legitimately
done these days, right?

On Tue, 18 Jan 2005 00:15:43 GMT, Edwin Pawlowski <[email protected]> wrote:
>
> "Dave Hinz" <[email protected]> wrote in message
>>>
>>> Kind'a like buying a "chip" to gain 30HP on your car, I suppose.
>>
>> You do know that that is how performance mods are legitimately
>> done these days, right?
>
> What? My water injector and the little fans in the carb venturii are
> outdated?

Well, water injection is also a legitimate technique - reduces
combustion chamber temperature, and increases effective compression.
A two-for-one effect in engines which can take advantage of it
(turbo or super-charged, with engine management that can sense knock
and adjust timing accordingly). Not sure about fans in the
carb venturi, that sounds like a "magnets on the fuel line" kind of
thing?

On Tue, 18 Jan 2005 12:13:21 -0500, George <george@least> wrote:
>
> "Dave Hinz" <[email protected]> wrote in message
> news:[email protected]...
>> Well, water injection is also a legitimate technique - reduces
>> combustion chamber temperature, and increases effective compression.
>> A two-for-one effect in engines which can take advantage of it
>> (turbo or super-charged, with engine management that can sense knock
>> and adjust timing accordingly). Not sure about fans in the
>> carb venturi, that sounds like a "magnets on the fuel line" kind of
>> thing?
>
> Sure augmented thrust on our old turbojets when the water kicked in.

Yup, it's real-world. Rolls-Royce was using it in aircraft engines
at least as far back as WWII. I imagine it works in similar ways in
a turbine engine (higher compression and able to burn more fuel cooler)?

Doug Miller wrote:
...
> Consider that the SawStop not only stops the blade, but also drops it below
> the table.

But not until it has already hit <something>...that's not to say it may
not minimize some degree of damage relative to not having it.

dwright wrote:
>
> Here's the text from page 66 of FWW #174:
>
> "I stuck a hot dog on the end of a stick and swung it into the moving
> blade as fast as I could. The result was a 1/16-in.ideep by
> 1/8"-in.-wide by 3/16"-in.-long cut. One of the students, a medical
> doctor, said that such a wound would require two or three stiches at
> most."
>
> The blade not only stops - it also drops below the table top. Sounds
> like the blade got out of the way before, even stopped, it could cut
> the hot dog in two.

I'm a lot more concerned about a digit simply being in the wrong place
along w/ the lumber being cut...I don't see how that would (or could) be
detected.

I also read the FWW review article and don't recall the test of
strapping the hotdog on a piece of oak and running the combination
through the blade...

GregP wrote:
>
> On Wed, 12 Jan 2005 09:16:29 -0600, Duane Bozarth
> <[email protected]> wrote:
>
> >
> >I'm a lot more concerned about a digit simply being in the wrong place
> >along w/ the lumber being cut...I don't see how that would (or could) be
> >detected.
>
> What does the lumber have to do with it ?

If the saw won't cut lumber w/o a pinkie (or hot dog), it won't be of
much use will it? :)

I'm simply questioning whether the detection capability is able to
distinguish a piece of flesh in the way while there's still a continued
normal cutting load and have seen no indication of a test to show it any
any review...

But still doesn't answer the question of whether it can detect the
condition of hand on board into the saw...which is the only case I've
ever even come close to finding myself in. I've never had any concern
of just putting my hand into the blade by itself...

dwright wrote:
>
> Duane,
>
> The brake works whenever it touches your blood stream regardless of
> whether it is also cutting wood at the time. In fact, the standard
> hotdog demo that SawStop runs at trade shows is with the dog perched
> on top of a piece of 3/4" plywood. The plywood is being cut at the
> exact same time as the hotdog is sensed and the blade stops &
> drops. You could be churning through 12/4 rock maple under enormous
> feed pressure straining your 5 HP 3 phase motor to the max, happen to
> run your finger across the top of the blade, and the brake would still
> work. The sensing system is independent.
>

Well, that's fairly impressive if it actually works...

ted harris wrote:
>
> In news:Duane Bozarth <[email protected]> typed:
> > But still doesn't answer the question of whether it can detect the
> > condition of hand on board into the saw...which is the only case I've
> > ever even come close to finding myself in. I've never had any concern
> > of just putting my hand into the blade by itself...
>
> www.sawstop.com has all the video you will ever need to see...

I have insufficient bandwidth to use 'net that way...

"Ron Short" <[email protected]> wrote in message
news:[email protected]...
> I laugh every time I watch NYW and see the safety segment where Norm's
hand
> slips. I always thought they could have chosen a better clip than that to
> show safety.

You have to be able to think.

What's important is not that there's a slip, it's that hand placement was
safe. Good lesson to learn.

Other SawStop reports are starting to trickle in. Search for posts by
"Vanguard" @ woodnet.net and "Dave Wright #2" (me) @ sawmillcreek.org.
I also put up a detailed review with editing help from LRod @
woodcentral.com.

http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=reviews&file=articles_484.shtml

I think the terse FWW by Kelly Mehler mentioned that he had swung a
hotdog on a stick into the blade and only got a minor cut. I don't
know how he set that up, but it sounds faster than my hand slipping
off a pushstick. You have to see the demo in person to appreciate
how quickly the blade brake acts. The most striking thing, for me at
least, was the dead silence afterward. We're used to hearing a saw
spool down after being turned off. During the demo the saw is
chugging away normally and then pop the blade is gone and it's
completely quiet. The demo I saw at IWF was with the hotdog being
fed much more quickly than I've ever cut plywood.

IMO SawStop really needs to work on their website, and they should do
it before their backorder list is gone. The site should tell a lot
more about the differences between their saws and competing ones.
They could include links to magazine reviews and independent reviews
such as this thread and the ones I mentioned. It would be cool if
they put together and maintained an accurate and reasonable schedule
for delivery of the saws, told you at the time of preorder about when
to expect delivery, and followed up with an e-mail each month giving
an update.

I suspect that what they're doing is letting matters take their
natural course and avoiding overexpansion. They might want to build
the number of saws that are out there slowly. Beta saws have been
working in shops since April 2004 but what if some obscure
operational or quality control issue comes up? Better to have to
rework 100 saws than 1000.

My guess is that they will have to face serious expansion questions
about when the thousandth saw ships. That will be mid-2005, and
might roughly coincide with reduction of the backorder list to a
reasonable length. By that time the Wood and AW articles will have
printed, they should have ironed out any obscure issues, and
production should be rolling. They will then have to make important
marketing, distribution, and service decisions.

Here's the text from page 66 of FWW #174:

"I stuck a hot dog on the end of a stick and swung it into the moving
blade as fast as I could. The result was a 1/16-in.ideep by
1/8"-in.-wide by 3/16"-in.-long cut. One of the students, a medical
doctor, said that such a wound would require two or three stiches at
most."

The blade not only stops - it also drops below the table top. Sounds
like the blade got out of the way before, even stopped, it could cut
the hot dog in two.

Duane,

The brake works whenever it touches your blood stream regardless of
whether it is also cutting wood at the time. In fact, the standard
hotdog demo that SawStop runs at trade shows is with the dog perched
on top of a piece of 3/4" plywood. The plywood is being cut at the
exact same time as the hotdog is sensed and the blade stops &
drops. You could be churning through 12/4 rock maple under enormous
feed pressure straining your 5 HP 3 phase motor to the max, happen to
run your finger across the top of the blade, and the brake would still
work. The sensing system is independent.

Best, Dave

Evidently the device does actually work. SawStop says that, during
development, testing, and public demos, they have triggered the brake
over a thousand times. One could discount that testimony as a
magician endorsing their own parlor tricks. Maybe the SawStop
employee doing each demo nudged a switch with his foot as he was
feeding the plywood and hotdog through the blade. I guess that's why
Fine Woodworking ran their tests - to make sure that SawStop wasn't
tricking people. FWW concluded that the device is real and it
works.

The device is fairly simple. Once you understand it, you might wonder
why it hadn't been thought of sooner. They electrically isolate the
blade, then feed a low voltage signal to it. They monitor the signal
(about 3 volts). When the blade comes into contact with an object
that has a lot of electrical capacitance, such as a human body, the
signal voltage temporarily dips. This dip is much more pronounced
when contacting a person than when cutting wood - unless you commonly
rip pieces of wood that weigh 150 pounds, are at 80% moisture content,
and have large unbroken electrical pathways throughout similar to our
blood vessels.

Once contact is sensed the brake cartridge sends an electrical pulse
through a stainless steel wire that is holding a spring compressed.
The released spring pushes an aluminum brake pawl into the backside
of the spinning blade. The blade burys itself in the brake pawl.
Much of its rotational momentum is transferred into downward force,
much like a car with its motor racing being knocked off concrete
blocks, and the blade drops below the table top. This dropping
motion is allowed by a specially designed arbor block with a pivot
and spring loaded retainer.

To put the saw back into service you work the joined blade/pawl off
the arbor and mounting posts, install a new blade and brake
cartridge, and snap the arbor block back up into position. There is
no damage to the saw. SawStop says that many of their tests have
been on a single saw, and it is still running normally and in
adjustment.

The cabinet saw already released includes hardware to implement this
concept that may be overengineered and too carefully built. They are
very interested in having the device work properly. It will be
interesting, though morbid, to hear the first reports of actual
contact with operators in regular shop situations.

Hope This Helps,

Dave

George,

You are correct. A more accurate statement would be that the saw
blade has to make substantial electrical contact with the operator's
body. That can be accomplished through contact with a very small
cross section of the bloodstream or a larger skin area. The hotdog
demo, for example, involves electrical connection through the wet dog
and across the finger/dog contact patch to get to the operator's
body.

My saw senses contact whenever I touch the blade while it is stopped.
The brake doesn't go off, but the LED control panel flashes a warning
and the saw will not fire up until contact has ceased for at least
five seconds.

I have also (very carefully) touched the blade side while it was
running in Bypass Mode. The control panel flashed the contact
pattern, so I know that the brake would have released if I hadn't
been in Bypass.

The brake isn't activated by a charge (explosive). They use a strong
spring. Explosives would be difficult to ship, might not burn
properly when aged, and wouldn't push after the initial burst. The
spring is inexpensive, ages well, and continues to push the pawl into
the blade to ensure successful braking. The wire that holds the
spring compressed is stainless steel so it should age well. The
cartridge includes a resistance heater to keep the wire and capacitor
above 50 degrees F at all times - ensuring that the burn-through will
happen properly when needed.

Take Care,

Dave

Old Nick,

I have no idea how diy came up with that address for me. I didn't
type it anywhere when signing up. It's just designstrategies.net.

You've got a good hunch there. They had to include a bypass mode, and
I wouldn't be surprised if the first person who gets bitten while
using that mode sues SawStop claiming that they weren't running in
bypass.

I have discussed the technology and the resulting saw's engineering at
length with Steve Gass, as part of deciding whether or not to get one
so early, but didn't get around to asking if the cartridge holds a
record of operating patterns. It tells you if contact is sensed
while in Bypass...would be trivial for it to record that info.

Most of the saw's smarts are in the cartridge. That make upgrades
easier. If you happen to have endured reading my review you might
have noticed that my saw received such an upgrade after I noticed an
operational irregularity. At some point someone's got to try hacking
the cartridge.

Regards,

Dave

Oh yea - Bypass Mode is a little irritating to engage. They did that
to discourage its regular use. You have to hold a key turned for at
least a second while starting the saw.

Ha! It may not work. The switch is a momentary contact keyswitch and
it would have been easy for SawStop to program the routine so that it
must start open, be held closed for 1 to 2 seconds, and go back open
or else the saw won't run. I don't know that they did that though.
I might give it a try for the heck of it next time I'm out in the
shop.

J.,

The Bypass Mode routine is to hold the key turned while pulling out
the on/off paddle. Hold that key position for at least a second
while the motor spools up. Then release the key. It's worked every
time I tried it. I haven't tried subtle timing variations to explore
the engagement algorithm.

Dave

"Dave Hinz" <[email protected]> wrote in message
news:[email protected]...
> Well, water injection is also a legitimate technique - reduces
> combustion chamber temperature, and increases effective compression.
> A two-for-one effect in engines which can take advantage of it
> (turbo or super-charged, with engine management that can sense knock
> and adjust timing accordingly). Not sure about fans in the
> carb venturi, that sounds like a "magnets on the fuel line" kind of
> thing?
>

Sure augmented thrust on our old turbojets when the water kicked in.

On Sun, 9 Jan 2005 15:29:41 -0500, "Mike Marlow"
<[email protected]> wrote:



>6 1/2 feet per second? Man, I can't feed wood that fast on my table saw. I
>need a better table saw.


that's not the speed of the wood- it's the speed of your hand when it
slips off of the wood and you lean in to catch yourself.

"J. Clarke" <[email protected]> wrote in message
news:[email protected]...
>
> While I doubt that anyone would move wood through the saw that fast, if
> you
> hand slips or something startles you that's another story. 4.5 MPH is a
> fast walk--it's not hard to move your hand faster than that.

Yes , true, some one is going to do that eventually.

>
> And according to Sawstop's own claims about stopping time, the blade would
> be 10mm (not quite half an inch) into your finger, which for most of us
> means your finger would be more off than on--it might be hanging together
> by a bone sliver and the flesh on one side but it will definitely not be
> in
> good shape.

I'll agree to that also although a 1/2 in deep cut is still pretty serious,
think of how bad it would be if the blade continued to spin with out any
type of stop. I can assure you that your reaction is not fast enough to
stop pushing your hand or finger through. Been there done that with a blade
that was coasting down to stop. I almost cut my thumb off at 2 places and
untill I saw the blood was under the firm belief that I had a kick back.

J. Clarke wrote:
> Leon wrote:
>
>
>>"Frank Ketchum" <[email protected]> wrote in message
>>news:[email protected]...
>>
>>>"W.L.Hall Workshop" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>
>>>>SawStop has provided us with a spare brake cartridge, so we will be
>>>>"test
>>>>firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us
>>>>if your in the area (Minneapolis).
>>>>
>>>
>>>Wish I could. Would it be possible to take a video of the test and post?
>>>
>>>I have had doubts that the speed at which the saw stop system responds is
>>>adequate for the level of protection that they claim. I assume you are
>>>going to use a hot dog or some such to test this thing. Consider the
>>>speed at which the "finger" is moving when it contacts the blade. I am
>>>curious if the system will be adequate for a finger approaching the blade
>>>at something like 2000 mm/sec (about 6.5 feet/sec) which is the hand
>>>speed constant used to calculate safe distances in automation equipment
>>>with electronic safe guarding.
>>
>>I believe in the real world you hand is moving no where near 4.5 MPH
>>during any operation around a TS unless you are jerking you hand back.
>
>
> While I doubt that anyone would move wood through the saw that fast, if you
> hand slips or something startles you that's another story. 4.5 MPH is a
> fast walk--it's not hard to move your hand faster than that.
>
> And according to Sawstop's own claims about stopping time, the blade would
> be 10mm (not quite half an inch) into your finger, which for most of us
> means your finger would be more off than on--it might be hanging together
> by a bone sliver and the flesh on one side but it will definitely not be in
> good shape.
>


Hmmm, I recall a woodworking journal publishing a test a couple of
issues ago that included whaping chicken leg as fas as they could into
the blade. It resouted in a small cut (1-2 stitch size).... pretty
limited damage considering.

Doug Miller wrote:
> In article <kx%[email protected]>, "George E. Cawthon" <[email protected]> wrote:
>
>>I find it difficult to believe that a hotdog swung into the
>>sawblade would result in a minor cut. Swinging a hotdog at
>>a completely stopped blade would likely result in the hotdog
>>being cut in half. I know if I swung my hand into my
>>stopped blade I would have a serious injury.
>
>
> Consider that the SawStop not only stops the blade, but also drops it below
> the table.
>
> --
> Regards,
> Doug Miller (alphageek-at-milmac-dot-com)
>
> Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
> by sending email to autoresponder at filterinfo-at-milmac-dot-com
> You must use your REAL email address to get a response.
>
>

Aha! Thanks. I don't remember seeing anyone mention that!

Must be a high powered charge to force 3" of blade out of
the way while a hand was moving at 6 feet per second next to
the table.

I laugh every time I watch NYW and see the safety segment where Norm's hand
slips. I always thought they could have chosen a better clip than that to
show safety.

"LRod" <[email protected]> wrote in message
news:[email protected]...
> On Sun, 09 Jan 2005 14:57:29 -0700, [email protected] wrote:
>
> >On Sun, 9 Jan 2005 15:29:41 -0500, "Mike Marlow"
> ><[email protected]> wrote:
> >
> >
> >
> >>6 1/2 feet per second? Man, I can't feed wood that fast on my table
saw. I
> >>need a better table saw.
> >
> >
> >that's not the speed of the wood- it's the speed of your hand when it
> >slips off of the wood and you lean in to catch yourself.
>
> A superb visual example of that is watching the video clip used in
> Norm's safety speech on NYW the last several years. As he's feeding a
> piece through the router table (quite nicely held down with feather
> boards, by the way) his forward hand slips. I cringe every time I see
> it, even though there's no danger, as I've had my hand slip on a piece
> of work before, too, and I can well imagine that happening around a
> cutting implement.
>
> By the way, I was taught long ago never to have one's hands over the
> rotating cutter head on a jointer when feeding stock through it for
> that very reason (the stock shooting out, not the hands slipping), yet
> I see virtually every TV wooddorker violating that every single time
> they joint.
>
>
> - -
> LRod
>
> Master Woodbutcher and seasoned termite
>
> Shamelessly whoring my website since 1999
>
> http://www.woodbutcher.net

"W.L.Hall Workshop" <[email protected]> wrote in message
news:[email protected]...

Thanks for taking the time to report to us.

"Frank Ketchum" <[email protected]> wrote in message
news:[email protected]...
>
> "W.L.Hall Workshop" <[email protected]> wrote in message
> news:[email protected]...
>
> >
> > SawStop has provided us with a spare brake cartridge, so we will be
"test
> > firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us
if
> > your in the area (Minneapolis).
> >
>
> Wish I could. Would it be possible to take a video of the test and post?
>
> I have had doubts that the speed at which the saw stop system responds is
> adequate for the level of protection that they claim. I assume you are
> going to use a hot dog or some such to test this thing. Consider the
speed
> at which the "finger" is moving when it contacts the blade. I am curious
if
> the system will be adequate for a finger approaching the blade at
something
> like 2000 mm/sec (about 6.5 feet/sec) which is the hand speed constant
used
> to calculate safe distances in automation equipment with electronic safe
> guarding.
>
> In any case, thanks for the info and please post results.
>
> Frank
>
>

6 1/2 feet per second? Man, I can't feed wood that fast on my table saw. I
need a better table saw.
--

-Mike-
[email protected]

"Dave Hinz" <[email protected]> wrote in message
>>
>> Kind'a like buying a "chip" to gain 30HP on your car, I suppose.
>
> You do know that that is how performance mods are legitimately
> done these days, right?

What? My water injector and the little fans in the carb venturii are
outdated?

"W.L.Hall Workshop" <[email protected]> wrote in message
news:[email protected]...

>
> SawStop has provided us with a spare brake cartridge, so we will be "test
> firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us if
> your in the area (Minneapolis).
>

Wish I could. Would it be possible to take a video of the test and post?

I have had doubts that the speed at which the saw stop system responds is
adequate for the level of protection that they claim. I assume you are
going to use a hot dog or some such to test this thing. Consider the speed
at which the "finger" is moving when it contacts the blade. I am curious if
the system will be adequate for a finger approaching the blade at something
like 2000 mm/sec (about 6.5 feet/sec) which is the hand speed constant used
to calculate safe distances in automation equipment with electronic safe
guarding.

In any case, thanks for the info and please post results.

Frank

"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> I believe in the real world you hand is moving no where near 4.5 MPH
during
> any operation around a TS unless you are jerking you hand back.

I can easily imagine your hand moving into the blade at that speed if it
were to slip off of a push stick or similar.

todd

"Todd Fatheree" <[email protected]> wrote in message
news:[email protected]...
>
> I can easily imagine your hand moving into the blade at that speed if it
> were to slip off of a push stick or similar.


Perhaps so and especially if you were not taking precautions against the
possibility of your hand slipping off a push stick. Having been in a rather
grizzly accident myself, I try to guard against that scenario also but
accidents can still happen as no one is perfect 100% of the time.

Leon wrote:

>
> "Frank Ketchum" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "W.L.Hall Workshop" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>>
>>> SawStop has provided us with a spare brake cartridge, so we will be
>>> "test
>>> firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us
>>> if your in the area (Minneapolis).
>>>
>>
>> Wish I could. Would it be possible to take a video of the test and post?
>>
>> I have had doubts that the speed at which the saw stop system responds is
>> adequate for the level of protection that they claim. I assume you are
>> going to use a hot dog or some such to test this thing. Consider the
>> speed at which the "finger" is moving when it contacts the blade. I am
>> curious if the system will be adequate for a finger approaching the blade
>> at something like 2000 mm/sec (about 6.5 feet/sec) which is the hand
>> speed constant used to calculate safe distances in automation equipment
>> with electronic safe guarding.
>
> I believe in the real world you hand is moving no where near 4.5 MPH
> during any operation around a TS unless you are jerking you hand back.

While I doubt that anyone would move wood through the saw that fast, if you
hand slips or something startles you that's another story. 4.5 MPH is a
fast walk--it's not hard to move your hand faster than that.

And according to Sawstop's own claims about stopping time, the blade would
be 10mm (not quite half an inch) into your finger, which for most of us
means your finger would be more off than on--it might be hanging together
by a bone sliver and the flesh on one side but it will definitely not be in
good shape.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Leon wrote:

>
> "J. Clarke" <[email protected]> wrote in message
> news:[email protected]...
>>
>> While I doubt that anyone would move wood through the saw that fast, if
>> you
>> hand slips or something startles you that's another story. 4.5 MPH is a
>> fast walk--it's not hard to move your hand faster than that.
>
> Yes , true, some one is going to do that eventually.
>
>>
>> And according to Sawstop's own claims about stopping time, the blade
>> would be 10mm (not quite half an inch) into your finger, which for most
>> of us means your finger would be more off than on--it might be hanging
>> together by a bone sliver and the flesh on one side but it will
>> definitely not be in
>> good shape.
>
> I'll agree to that also although a 1/2 in deep cut is still pretty
> serious, think of how bad it would be if the blade continued to spin with
> out any
> type of stop.

I don't know about your fingers but on mine it wouldn't be much worse. 1/2
inch in most if not all of the works would be severed and what's left would
probably work about the same afterwards as if it had been completely off.

> I can assure you that your reaction is not fast enough to
> stop pushing your hand or finger through. Been there done that with a
> blade
> that was coasting down to stop. I almost cut my thumb off at 2 places and
> untill I saw the blood was under the firm belief that I had a kick back.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Duane Bozarth wrote:

> dwright wrote:
>>
>> Here's the text from page 66 of FWW #174:
>>
>> "I stuck a hot dog on the end of a stick and swung it into the moving
>> blade as fast as I could. The result was a 1/16-in.ideep by
>> 1/8"-in.-wide by 3/16"-in.-long cut. One of the students, a medical
>> doctor, said that such a wound would require two or three stiches at
>> most."
>>
>> The blade not only stops - it also drops below the table top. Sounds
>> like the blade got out of the way before, even stopped, it could cut
>> the hot dog in two.
>
> I'm a lot more concerned about a digit simply being in the wrong place
> along w/ the lumber being cut...I don't see how that would (or could) be
> detected.

That's the whole point of it. It uses electrical signatures--a finger has a
different signature than a piece of wood and it can distinguish the two
most of the time--it seems to be designed to err on the side of caution--it
apparently will trigger with some species of wood if cut green for example
because the signature is similar to a finger.

> I also read the FWW review article and don't recall the test of
> strapping the hotdog on a piece of oak and running the combination
> through the blade...

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Duane Bozarth wrote:

> dwright wrote:
>>
>> Duane,
>>
>> The brake works whenever it touches your blood stream

Doesn't have anything to do with "touching your blood stream". Touching the
side of the blade will also trigger it I understand.

>> regardless of
>> whether it is also cutting wood at the time. In fact, the standard
>> hotdog demo that SawStop runs at trade shows is with the dog perched
>> on top of a piece of 3/4" plywood. The plywood is being cut at the
>> exact same time as the hotdog is sensed and the blade stops &
>> drops. You could be churning through 12/4 rock maple under enormous
>> feed pressure straining your 5 HP 3 phase motor to the max, happen to
>> run your finger across the top of the blade, and the brake would still
>> work. The sensing system is independent.
>>
>
> Well, that's fairly impressive if it actually works...

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Duane Bozarth wrote:

> But still doesn't answer the question of whether it can detect the
> condition of hand on board into the saw...which is the only case I've
> ever even come close to finding myself in. I've never had any concern
> of just putting my hand into the blade by itself...

That's what it's intended to do. There's discussion of how it goes about
this on the Sawstop site.

While there are a lot of concerns about its function and utility, being able
to trigger under the circumstance you describe has not been one of them.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Old Nick wrote:

> On 12 Jan 2005 22:00:57 -0500,
> [email protected] (dwright) vaguely
> proposed a theory
> ......and in reply I say!:
>
> remove ns from my header address to reply via email
>
>>I have also (very carefully) touched the blade side while it was
>>running in Bypass Mode. The control panel flashed the contact
>>pattern, so I know that the brake would have released if I hadn't
>>been in Bypass.
>
> Wait! There's a Bypass mode? Operator controllable? Uhoh! Suit City
> here we come, I reckon.
>
> "Should I run my sawstop in bypass mode?" will replace "should I have
> a blade guard installed?" ?

Not really, bypass mode is specifically for metals and green wood that would
trigger the Sawstop otherwise.

> In a working situation, is there any _record/log_ kept of each
> incident, and the state of the Saw Stop?

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Old Nick wrote:

> On 13 Jan 2005 23:00:58 -0500,
> [email protected] (dwright) vaguely
> proposed a theory
> ......and in reply I say!:
>
> remove ns from my header address to reply via email
>
>>Oh yea - Bypass Mode is a little irritating to engage. They did that
>>to discourage its regular use. You have to hold a key turned for at
>>least a second while starting the saw.
>
> But it will be done...<G>
>
> Seriously, I am surprised they included it. Even after readin your
> other post.

If they didn't then a lot of people would need two saws, one with Sawstop
and one without.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

"dwright" <[email protected]> wrote in
message news:[email protected]...
> Oh yea - Bypass Mode is a little irritating to engage. They did that
> to discourage its regular use. You have to hold a key turned for at
> least a second while starting the saw.

duct tape

Charles Spitzer wrote:

>
> "dwright" <[email protected]> wrote in
> message news:[email protected]...
>> Oh yea - Bypass Mode is a little irritating to engage. They did that
>> to discourage its regular use. You have to hold a key turned for at
>> least a second while starting the saw.
>
> duct tape

But does the key also have to be released in order to engage it?

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

When you do the "test run", consider pushing the hot dog "rapidly" into the
blade, as described in some of the posts here. And report back the results.
Inquiring fingers would like to know!!!!

Bob


"W.L.Hall Workshop" <[email protected]> wrote in message
news:[email protected]...
> sent to:
> rec.woodworking
> [email protected]
> [email protected]
> [email protected]
>
> from:
> [email protected]
> http://www.cala.umn.edu/workshop/
>
> Hey All.
>
> We got our 2 sawstop saws on 12/28/04
>
> I've spent the last couple weeks setting em up - biesmeyer overhead
> bladeguards, full outfeed tables, excalibur/exactor sliding tables. I'd
> forgotten how long it takes to set up shop.
>
> We haven't run the saws much yet, but here are some observations I've made
> so far.
>
> quality -
> These machines seem as well built as the unisaw that we bought 4 years
> ago(not saying much really). An extention table flatness problem has been
> mentioned, but our tables and rt wings are flat within .010". We never put
> on the left wings since we installed sliding tables, so I cannot speak to
> that issue. The trunnions, arbor shaft, bearings, and even the main table
> are beefier than comparable parts on a unisaw and I think even a pm 66.
> The polished handwheels are big and heavy with very nicely spinning
> cranks. Height & angle adjustment are smooth and easy (of course the
> machines are brand new, so they better be) .
> I'd like a polished tabletop, and these are just ground, but that will
> make the first scratches less painful.
> The machines are smoother and quieter than the last unisaw was when new.
> A nickel sits on edge on the tabletop from start up through cutting 8/4
> maple through shut down.
> Initial indications are that these machines are well made. - time will
> tell.
>
> design -
> There is alot going on inside of these saws.
> I like the linear (rather than arc) raising action, it seems much more
> intuitive even if more complicated.
> A gas spring supports the arbor and assists blade raising.
> The splitter/blade guard/riving knife is EXCELLENT - easy to change, easy
> to adjust, and wedded to blade height like it should be.
> The blade guard itself is only about 1-1/4" wide and contoured to "hug"
> the blade- much less obtrusive than traditional guards.
> We will likely ALWAYS use the riving knife and the overhead blade guard.
> I expect significantly fewer kickbacks as a result of the "invisible"
> riving knife.
> The brake cartridge is not the easiest thing to change- but it will
> probably become easier as we do it.
> The extenion table is gloss black laminate. Black? Gloss? Can you say
> glare? We will probably start with sanding out the gloss, then get rid of
> the black if it is still too annoying. Sawstop took the color theme WAY
> too far here.
> I look forward to seeing how the DC shroud works, but this is an arbor
> nutsucker waiting to happen.
> What happens to the dust that gets past the DC shroud, how much dust will
> build up inside the cabinet, how hard will it be to get out?
> If the DC shroud is effective, it should keep all of the other parts
> cleaner for smooth operation and less wear.
> The large access door should allow enough access to service the saw, but
> it's under the extension table, so it still won't be easy.
> The belt access door seems appropriate, not sure about the single splined
> belt - seems a bit light.
> The bump switch is well located and a good size, after not much use, we
> should be able to easily shut off the saw, but it will be a while before
> we stop doing so inadvertently. The arbor/arbor nut wrenches are WAY TOO
> BIG, this will encourage overtightening and our ARBORS will be STRIPPED in
> no time. Are you reading this Steve?
> The fence is a biesmeyer clone - faces are replaceable with "keyhole
> slots" - this is ok, but I don't really feel that they are flat/secure
> with no way to tighten them.
> Rare earth magnets on the fence lever and dust shroud door are nice
> details, as is the "soft" fence handle.
> The "power disconect switch" is on the rear of the left side of the
> cabinet (beneath our sliding table) this is too hard to get to for routine
> blade changes etc...
> In order to get inside the cabinet to change the brake/make adjustments,
> the throat opening is larger than a unisaw's. This is ok access-wise, but
> having less of a smooth, flat tabletop can be problematic.
> The process to "by-pass" the sawstop machanism must be done each time the
> saw started in by-pass.- a pain if we're cutting a buch of aluminum all
> day.
>
> issues-
> We occasionally used 8 1/4" thin kerf (3/64") blades for slotting and
> making scale lumber - sawstop requires 10" blades or 8" dados.
> Hmmm, if we use the dado brake and an 8-1/4" blade...
> We need to explain to 500 college students why and how the saws are
> different.
> Gloss black extension table?
> Seperate arbor nut/washer invites droppage into dust collection and
> "washerless" re-installation. (We had welded a washer to a nut to
> eliminate this on unisaws)
> I have to get rid of 2 old unisaws, 1 jet sliding table and 1 excalibur
> bladeguard.
> The height of the back fence rail makes it impossible to mount a flush
> outfeed table (same as biesmeyer). I re-drilled and lowered, now 1 of the
> doors doesn't open past he rail, arggggh.
>
> SawStop has provided us with a spare brake cartridge, so we will be "test
> firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us if
> your in the area (Minneapolis).
>
> It seems that there are few reports of sawstops in action on the web, so I
> will try to post to rec.woodworking if anything of interest comes up.
>
> Enough for now, smoke if you got em.
>
> KG

On Wed, 12 Jan 2005 12:30:36 -0600, Duane Bozarth
<[email protected]> wrote:

>
>I'm simply questioning whether the detection capability is able to
>distinguish a piece of flesh in the way while there's still a continued
>normal cutting load and have seen no indication of a test to show it any
>any review...

It doesn't detect flesh per se, it's looking for a change in electric
potential. Have you ever been in a building that has a door with
a crash bar that youhave to touch with your bare hand in order to
release a magnet that holds the door closed ?

On 13 Jan 2005 22:00:48 -0500,
[email protected] (dwright) vaguely
proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email
>I have no idea how diy came up with that address for me. I didn't
>type it anywhere when signing up. It's just designstrategies.net.

Well it sounds as if somebody cares about your bum for you. Anti-spam
addresses on the newsgroup are very common, to stop....well...spammers
<G>. Hence my little request to remove ns when replying by email.

>You've got a good hunch there. They had to include a bypass mode, and
>I wouldn't be surprised if the first person who gets bitten while
>using that mode sues SawStop claiming that they weren't running in
>bypass.
>
>I have discussed the technology and the resulting saw's engineering at
>length with Steve Gass, as part of deciding whether or not to get one
>so early, but didn't get around to asking if the cartridge holds a
>record of operating patterns. It tells you if contact is sensed
>while in Bypass...would be trivial for it to record that info.

I remain neutral about SawStop. Which to say against, really, as I
have not bought one <G>. But this one seems to be for _their_
protection.

>
>Most of the saw's smarts are in the cartridge. That make upgrades
>easier. If you happen to have endured reading my review you might
>have noticed that my saw received such an upgrade after I noticed an
>operational irregularity. At some point someone's got to try hacking
>the cartridge.

"dwright" <[email protected]> wrote in
message news:[email protected]...

> At some point someone's got to try hacking
> the cartridge.

Kind'a like buying a "chip" to gain 30HP on your car, I suppose.

dwright wrote:
> Other SawStop reports are starting to trickle in. Search for posts by
> "Vanguard" @ woodnet.net and "Dave Wright #2" (me) @ sawmillcreek.org.
> I also put up a detailed review with editing help from LRod @
> woodcentral.com.
>
> http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=reviews&file=articles_484.shtml
>
> I think the terse FWW by Kelly Mehler mentioned that he had swung a
> hotdog on a stick into the blade and only got a minor cut. I don't
> know how he set that up, but it sounds faster than my hand slipping
> off a pushstick. You have to see the demo in person to appreciate
> how quickly the blade brake acts. The most striking thing, for me at
> least, was the dead silence afterward. We're used to hearing a saw
> spool down after being turned off. During the demo the saw is
> chugging away normally and then pop the blade is gone and it's
> completely quiet. The demo I saw at IWF was with the hotdog being
> fed much more quickly than I've ever cut plywood.
>

I find it difficult to believe that a hotdog swung into the
sawblade would result in a minor cut. Swinging a hotdog at
a completely stopped blade would likely result in the hotdog
being cut in half. I know if I swung my hand into my
stopped blade I would have a serious injury.

Hello,

Actually, it has nothing to do with conductivity (resistance), but with
capacitance, ie the proportion of your boddy to load with static
electricity.

regards, cyrille


"Tim Douglass" <[email protected]> wrote in message
news:[email protected]...
> On Wed, 12 Jan 2005 12:30:36 -0600, Duane Bozarth
> <[email protected]> wrote:
>
>>If the saw won't cut lumber w/o a pinkie (or hot dog), it won't be of
>>much use will it? :)
>>
>>I'm simply questioning whether the detection capability is able to
>>distinguish a piece of flesh in the way while there's still a continued
>>normal cutting load and have seen no indication of a test to show it any
>>any review...
>
> The detection has nothing to do with the load the saw is under. It is
> similar to what is used on the "touch lamps" and detects contact with
> a conductor. Because of that false triggers due to very green lumber
> (or wet pressure treated), metal in the wood or other possibly
> conductive things are a concern.
>
> Tim Douglass
>
> http://www.DouglassClan.com

"Frank Ketchum" <[email protected]> wrote in message
news:[email protected]...
>
> "W.L.Hall Workshop" <[email protected]> wrote in message
> news:[email protected]...
>
>>
>> SawStop has provided us with a spare brake cartridge, so we will be "test
>> firing" a saw on Thursday, Jan 13th at 3:00pm. Your welcome to join us
>> if your in the area (Minneapolis).
>>
>
> Wish I could. Would it be possible to take a video of the test and post?
>
> I have had doubts that the speed at which the saw stop system responds is
> adequate for the level of protection that they claim. I assume you are
> going to use a hot dog or some such to test this thing. Consider the
> speed at which the "finger" is moving when it contacts the blade. I am
> curious if the system will be adequate for a finger approaching the blade
> at something like 2000 mm/sec (about 6.5 feet/sec) which is the hand speed
> constant used to calculate safe distances in automation equipment with
> electronic safe guarding.

I believe in the real world you hand is moving no where near 4.5 MPH during
any operation around a TS unless you are jerking you hand back.

On Wed, 12 Jan 2005 12:30:36 -0600, Duane Bozarth
<[email protected]> wrote:

>If the saw won't cut lumber w/o a pinkie (or hot dog), it won't be of
>much use will it? :)
>
>I'm simply questioning whether the detection capability is able to
>distinguish a piece of flesh in the way while there's still a continued
>normal cutting load and have seen no indication of a test to show it any
>any review...

The detection has nothing to do with the load the saw is under. It is
similar to what is used on the "touch lamps" and detects contact with
a conductor. Because of that false triggers due to very green lumber
(or wet pressure treated), metal in the wood or other possibly
conductive things are a concern.

Tim Douglass

http://www.DouglassClan.com

On Thu, 13 Jan 2005 22:02:31 -0500, GregP <[email protected]>
vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

But does it work if you throw a sausage at it?

> It doesn't detect flesh per se, it's looking for a change in electric
>potential. Have you ever been in a building that has a door with
>a crash bar that youhave to touch with your bare hand in order to
> release a magnet that holds the door closed ?

On 12 Jan 2005 22:00:57 -0500,
[email protected] (dwright) vaguely
proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>I have also (very carefully) touched the blade side while it was
>running in Bypass Mode. The control panel flashed the contact
>pattern, so I know that the brake would have released if I hadn't
>been in Bypass.

Wait! There's a Bypass mode? Operator controllable? Uhoh! Suit City
here we come, I reckon.

"Should I run my sawstop in bypass mode?" will replace "should I have
a blade guard installed?" ?

In a working situation, is there any _record/log_ kept of each
incident, and the state of the Saw Stop?

On Fri, 14 Jan 2005 05:29:59 -0500, "J. Clarke"
<[email protected]> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>> Seriously, I am surprised they included it. Even after readin your
>> other post.
>
>If they didn't then a lot of people would need two saws, one with Sawstop
>and one without.

Oh I can see the need! I just feel it will _legally_ negate the whole
thing somewhere down the track, unless they cover their arses very
carefully.

On Wed, 12 Jan 2005 09:16:29 -0600, Duane Bozarth
<[email protected]> wrote:

>
>I'm a lot more concerned about a digit simply being in the wrong place
>along w/ the lumber being cut...I don't see how that would (or could) be
>detected.

What does the lumber have to do with it ?

On Fri, 14 Jan 2005 11:28:28 -0700, "Charles Spitzer"
<[email protected]> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>
>"dwright" <[email protected]> wrote in
>message news:[email protected]...
>> Oh yea - Bypass Mode is a little irritating to engage. They did that
>> to discourage its regular use. You have to hold a key turned for at
>> least a second while starting the saw.
>
>duct tape


Like I said...it will be done! <G>

On 13 Jan 2005 23:00:58 -0500,
[email protected] (dwright) vaguely
proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>Oh yea - Bypass Mode is a little irritating to engage. They did that
>to discourage its regular use. You have to hold a key turned for at
>least a second while starting the saw.

But it will be done...<G>

Seriously, I am surprised they included it. Even after readin your
other post.

In article <kx%[email protected]>, "George E. Cawthon" <[email protected]> wrote:
>
>I find it difficult to believe that a hotdog swung into the
>sawblade would result in a minor cut. Swinging a hotdog at
>a completely stopped blade would likely result in the hotdog
>being cut in half. I know if I swung my hand into my
>stopped blade I would have a serious injury.

Consider that the SawStop not only stops the blade, but also drops it below
the table.

--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)

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