Well, all I know is that when they demonstrate the thing with a hot dog it
stops virtually instantaneously. The dog has just a slight knick in it.

--
Jeff P.

"A new study shows that licking the sweat off a frog
can cure depression. The down side is, the minute
you stop licking, the frog gets depressed again." - Jay Leno


Check out my woodshop at: www.sawdustcentral.com


"J. Clarke" wrote in message
...
cg wrote:

As no one offered a little more explanation on how fast
this saw-stop really stops, I would present some simple maths...

From their website they say they can stop a 4000 rpm blade
in less than five (5) milliseconds.
Now, the blade normally takes 60 seconds for 4000 rounds.
In one millisecond, the blade would rotate 1/15 round...
(that is one part of fifteen).

So, if the sawstop mechanism takes 5 milliseconds to stop,
I would expect at most 5 x (1/15) ,that is, one-third of a full
rev of the blade to plough thru before it stops.

Say, I'm ripping with a 24 teeth blade. In 1/3 rev, I would
expect no more than 8 of those teeth to bite me. If I had
been using a 60 teeth cuutoff blade, watch out! 1/3 of 60
is 20!

To be honest, I would reduce the fraction from 1/3 to 1/4 or
1/5 because I have not taken into account the deceleration...
once the brake is applied, the blade is spinning down and it
is not rotating at 4000 RPM during the entire 5 milliseconds.
(So, how long it takes for brake shoes to engage? 1 millisec?)

Even then, for a 24 teeth ripper, 1/5 is 4+ teeth and
for a 60 teeth cutoff, 1/5 is 12 teeth. Little
consolation for me!

I wish the sawstop folks could give out details like
these. In particular, they must already have exact figures for the
rotation before complete stoppage. Instead of telling in terms
of time (like milliseconds) it would be better to state the same
in terms of percentage of a full rev of a 10" standard kerf blade
spinning at 4000 RPM.
Although I must agree there is more truth in their statement
compared to claims like 3.25 HP routers on 115v, or 12" SP/ 1200 cfm
with a 10" impeller 2 HP DC, and the like!

Afterall, they certainly have the brain to see through my simple math...
don't they?

So how many saw teeth have to go through your finger before your finger
comes off?

cg


(David Hall) wrote in message
. com...
otforme (Charlie Self) wrote in message While I
don't want to be flippant about the injury rates
listed in the article, I DO want to point out that there are
likely millions (or tens of millions) of usages of saws every year
in the USA. While taken out of context, the idea of thousands of
accidents seems like a lot, in context of the total number of times
a
table saw is used, it is a drop in the ocean.

My big gripe is the use of the word "amputations" in place of
injuries.
I'd also know where they get their statistics. I sure haven't found
them. Of course, I don't have a marketing impetus to actually spend
money looking, but if I had cites to back up such claims, I think I'd
make them available. So far, I've seen nothing but claims.

I am certainly not a big fan of this type of regulations. However,
someone did provide a source citation for the number of amputations.
That was the Federal Consumer Safety Protection Commission. See
http://www.cpsc.gov/library/neiss.html

I also understand that there would be few affordable cars with airbags
if they were not required and that deployment of an airbag adds quite
a bit to smaller accident repair costs. On the other hand a $250 to
$500 Sawstop will pretty much eliminate the $200 tablesaw and it is
doubtful one could be put onto a cheap tabletop saw anyhow. How many
fewer people are simply not going to be able to realistically
participate in the hobby if something like this is mandated. I am not
sure that, even though I consider myself a conservative, I am ready to
eliminate all regulartory aspects of government - I just would want to
err on the side of "freedom" in this area.

Dave Hall

Most of us who have been fooling and fiddling with tablesaws over the
years have received injuries of one sort or another, everything from
blade-changing knicks to kickback bruises the size of a draft horse's
shoe and, very occasionally, something more serious. If we're at all
wise, we learn from the smaller incidents and remain slightly in awe
of
what the tablesaw can do to us if our attention wanders. If we're not
particularly wise, we continue to use unsafe working methods and
eventually get hurt worse. It may not catch up to the inattentive
user
today, tomorrow or even next year, but it will catch up.

Charlie Self
"Health nuts are going to feel stupid someday, lying in hospitals
dying
of nothing."
Redd Foxx

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