There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.
In fact, if designed properly, you could proly have only the blade and its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST, anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal
be as fast as his collision process, AND be non-destructive? Mebbe multiple
calipers.

Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the
idears. Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the li'l
children....
--
EA

On Dec 8, 8:36*am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the advantage
of being non-destructive. *Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.
In fact, if designed properly, you could proly have only the blade and its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST, anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started. And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.

A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.



Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal
be as fast as his collision process, AND be non-destructive? *Mebbe multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.



Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?




*Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?

On 12/8/2012 9:56 AM, wrote:
On Dec 8, 8:36 am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.
In fact, if designed properly, you could proly have only the blade and its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST, anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started. And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.

A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.



Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal
be as fast as his collision process, AND be non-destructive? Mebbe multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.



Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?




Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?


Maybe if you two watched the video you'd understand.
The blade is stopped, and that is actually part of the retraction
mechanism. The inertia is dissipated by retracting.
The retracting saves the finger as well since it is pulling away from
the finger.

The design as it stands is very good, your ideas are not.
BTW this is a top notch saw, so no it is not direct drive.
The workmanship on all of these saws exceeds what we now currently have
from the standard non-euro options.

wrote in message
...
On Dec 8, 8:36 am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.
In fact, if designed properly, you could proly have only the blade and its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST, anyway,
to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started.
========================================

http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1
1:45 the retraction looks pretty complete to me.
BUT, at 2:50, which shows the whole process, it appears that the retraction
occurs AFTER the collision thingy engages.
Yet, at 1:45, the retraction seem instantaneous, upon touching the hot
dog.... Go figger.



And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.
=================================================

10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x the
weight of a 200# guy.
If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then it
would only be 200# of force, a lot more manageable.
800# is actually not a cosmically large force, given that some people can
lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe
too expensive to implement.




A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.
==================================================

I suspect the retraction is not for retraction's sake but as a kind of force
reaction to the stopped blade, preventing more damage than is already
occurring.




Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.
================================================== ===

Here's a way to do it:

If a quick retraction occurs over a relatively small distance, AND a
caliper-applied deceleration then occured (non-destructive), you'd have a
more time to stop the blade rotation, ie less demanding braking, no trashed
blade.
To wit:
Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a
saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec.
Now, upon the 1/2" retraction, the hand won't contact the blade for another
50 milliseconds, giving the blade 50x longer to stop, before the hand has
another chance to contact the blade -- a whole lot easier to accomplish
than a 1 millisecond stop.


I suspect the most feasible way to accomplish this kind of retraction is
with bigazz spring (proly two, on either side of the blade, moving two
bearings), triggered much the way the spring of his jamb-ditty is applied,
with the calipers simultaneously engaging.

Heh, and these calipers can act as a brake on the saw during normal use, as
well, instead of electric motor braking. Lathes often have a frictional
stop system, using a drum-like squeeze brake, very handy.




Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?
================================================

Mebbe he dudn't drive, or mow his lawn.



Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?
===============================================

Like they don't warrant it, right?
These corrupt assholes couldn't give a goddamm about you'n'me, but they are
surefire quick to up the regulational ante, and then **** the public for the
slightest transgression. Municipal penalty pricing, donchaknow.
With high enough penalties, they could eliminate taxes, and still remain in
the black.
--
EA

"tiredofspam" nospam.nospam.com wrote in message
...
On 12/8/2012 9:56 AM, wrote:
On Dec 8, 8:36 am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more
rapid,
since you would not have to retract the mass of a relatively heavy
motor.
In fact, if designed properly, you could proly have only the blade and
its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST,
anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started. And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.

A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.



Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.



Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes
the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?




Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the
li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?


Maybe if you two watched the video you'd understand.
The blade is stopped, and that is actually part of the retraction
mechanism. The inertia is dissipated by retracting.
The retracting saves the finger as well since it is pulling away from the
finger.

The design as it stands is very good, your ideas are not.
BTW this is a top notch saw, so no it is not direct drive.
The workmanship on all of these saws exceeds what we now currently have
from the standard non-euro options.

Really? And you know all this..... how??
--
EA

On Dec 8, 10:35*am, tiredofspam nospam.nospam.com wrote:
On 12/8/2012 9:56 AM, wrote:





On Dec 8, 8:36 am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the advantage
of being non-destructive. *Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.
In fact, if designed properly, you could proly have only the blade and its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST, anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started. *And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.

A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.

Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal
be as fast as his collision process, AND be non-destructive? *Mebbe multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. *With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.

Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?

* *Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?

Maybe if you two watched the video you'd understand.

I did watch the video. Nothing in the video shows exactly
how the blade retracts, what it's attached to beneath
the saw, etc. And there isn't just one video,
so how would you know what videos anyone did or did
not see.


The blade is stopped, and that is actually part of the retraction
mechanism. The inertia is dissipated by retracting.
The retracting saves the finger as well since it is pulling away from
the finger.

OK, using the momentum of the saw to retract the
blade makes sense. Is that all that causes the retraction
or is there something else, eg spring involved?



The design as it stands is very good, your ideas are not.
BTW this is a top notch saw, so no it is not direct drive.
The workmanship on all of these saws exceeds what we now currently have
from the standard non-euro options.- Hide quoted text -

- Show quoted text -

I think you're confused. You replied to my post. I did not
propose changing the SawStop. I'm fine with it. It was EA
that was proposing the new ideas and simply pointed out
some of the obvious issues.

On Dec 8, 10:55*am, "Existential Angst" wrote:
wrote in message

...
On Dec 8, 8:36 am, "Existential Angst" wrote:





There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more rapid,
since you would not have to retract the mass of a relatively heavy motor.

wrote in message
...
On Dec 8, 10:55 am, "Existential Angst" wrote:
wrote in message

...
On Dec 8, 8:36 am, "Existential Angst" wrote:





There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more
rapid,
since you would not have to retract the mass of a relatively heavy
motor.
In fact, if designed properly, you could proly have only the blade and
its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST,
anyway,
to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started.
========================================

http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1
1:45 the retraction looks pretty complete to me.
BUT, at 2:50, which shows the whole process, it appears that the
retraction
occurs AFTER the collision thingy engages.

Yet, at 1:45, the retraction seem instantaneous, upon touching the hot
dog.... Go figger.

Well, one is normal speed video, the other is high-speed
photography that is slowed down so you can actually
see what is happening.

At the 1:45 normal speed spot all you see is the top of the saw
and it's impossible to determine any sequence of
events. At the 2:50 area it's clear that a substantial amount
of the movement is ocurring after the saw blade has
stopped spinning.

Also, what "tired" just posted makes sense. The saw
has momentum that has to go somewhere. One place
to dissipate it is to allow the blade to go down in a
controlled fashion. It could be that is all they use. If so,
the sequence would be that the pawl engages first
and as it stops the saw, the momentum then causes
the retraction.




And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.
=================================================

10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x
the
weight of a 200# guy.
If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then
it
would only be 200# of force, a lot more manageable.
800# is actually not a cosmically large force, given that some people can
lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe
too expensive to implement.

I would expect the mass is more than 2.2 lbs.
And not clear how you'd apply such a large force.
If you used a spring for example, the mass of the spring
also has to be accounted for because you're also
accelerating that.
=============================================

Depends how you design it. I could see a strong magnesium housing to a
belt-driven blade being pretty lite.
And actually, a large spring IS the force-provider. Basically you'd have a
mouse-trap type situation, where a very small/fast actuator trips the
spring, which then applies the accelerating force -- one on each side of the
blade could supply wicked fast accelerations.

For example, Lee Spring in NYC has dies springs with spring constants of
over 2,000 # per inch.... and that's just one spring. So these forces are
easily obtainable in very small spaces, more than adequate for even multi-kg
blade housings.

Heh, resetting the blade, tho, would require crowbar.... LOL
But actually, could be done with fine-thread "resetting screw", might take a
cupla minutes.





A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.
==================================================

I suspect the retraction is not for retraction's sake but as a kind of
force
reaction to the stopped blade, preventing more damage than is already
occurring.



From "tired"'s reply it is indeed the saw momentum.
But he seems to imply that it also prevents the injury by
pulling the blade away. We'd have to see a very high-speed
close up of the hot dog video to see the exact sequence
and if the saw stopping alone isn't sufficient.







Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.
================================================== ===

Here's a way to do it:

If a quick retraction occurs over a relatively small distance, AND a
caliper-applied deceleration then occured (non-destructive), you'd have a
more time to stop the blade rotation, ie less demanding braking, no
trashed
blade.

Yes, IF you could retract it quicker than a finger can advance
for as long as it takes to stop the saw.




To wit:
Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a
saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec.
Now, upon the 1/2" retraction, the hand won't contact the blade for
another
50 milliseconds, giving the blade 50x longer to stop, before the hand has
another chance to contact the blade -- a whole lot easier to accomplish
than a 1 millisecond stop.

I suspect the most feasible way to accomplish this kind of retraction is
with bigazz spring (proly two, on either side of the blade, moving two
bearings), triggered much the way the spring of his jamb-ditty is applied,
with the calipers simultaneously engaging.

Heh, and these calipers can act as a brake on the saw during normal use,
as
well, instead of electric motor braking. Lathes often have a frictional
stop system, using a drum-like squeeze brake, very handy.




Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes
the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?
================================================

Mebbe he dudn't drive, or mow his lawn.

Or mebbe just invite me to one of them 'spensive luncheons, where

he's twisting CONgress's arms on safety'n'****, you know, for all the
li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?
===============================================

Like they don't warrant it, right?
These corrupt assholes couldn't give a goddamm about you'n'me, but they
are
surefire quick to up the regulational ante, and then **** the public for
the
slightest transgression. Municipal penalty pricing, donchaknow.
With high enough penalties, they could eliminate taxes, and still remain
in
the black.
--
EA- Hide quoted text -

- Show quoted text -


I've only looked into the SS itself a bit. I haven't looked into
what the inventor is or isn't doing regarding politicians, making
it mandatory, etc.
==================================================

Well, a few replies in the previous thread addressed this, and some forums
have discussed this at length. The almost universal consensus so far is
that his tactics/lobbying, altho legal, are manipulative and greed-driven.
(G)ass is quite at home with the lobbyists..

All's you gotta do is scream Safety loud enough, or " ....the li'l
children...". and BAM, everyfuknthing stops, sense goes out the window, and
you can rip off the system to yer heart's content. Ergo, Crawling Helmets.

I think that whiney asshole TiredofSpam has color-coordinated crawling
helmets, to match his diapers and Superman cape.
--
EA

On 12/8/2012 12:06 PM, Existential Angst wrote:
wrote in message
...
On Dec 8, 10:55 am, "Existential Angst" wrote:
wrote in message

...
On Dec 8, 8:36 am, "Existential Angst" wrote:





There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more
rapid,
since you would not have to retract the mass of a relatively heavy
motor.
In fact, if designed properly, you could proly have only the blade and
its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST,
anyway,
to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started.
========================================

http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1
1:45 the retraction looks pretty complete to me.
BUT, at 2:50, which shows the whole process, it appears that the
retraction
occurs AFTER the collision thingy engages.

Yet, at 1:45, the retraction seem instantaneous, upon touching the hot
dog.... Go figger.

Well, one is normal speed video, the other is high-speed
photography that is slowed down so you can actually
see what is happening.

At the 1:45 normal speed spot all you see is the top of the saw
and it's impossible to determine any sequence of
events. At the 2:50 area it's clear that a substantial amount
of the movement is ocurring after the saw blade has
stopped spinning.

Also, what "tired" just posted makes sense. The saw
has momentum that has to go somewhere. One place
to dissipate it is to allow the blade to go down in a
controlled fashion. It could be that is all they use. If so,
the sequence would be that the pawl engages first
and as it stops the saw, the momentum then causes
the retraction.




And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.
=================================================

10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x
the
weight of a 200# guy.
If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then
it
would only be 200# of force, a lot more manageable.
800# is actually not a cosmically large force, given that some people can
lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe
too expensive to implement.

I would expect the mass is more than 2.2 lbs.
And not clear how you'd apply such a large force.
If you used a spring for example, the mass of the spring
also has to be accounted for because you're also
accelerating that.
=============================================

Depends how you design it. I could see a strong magnesium housing to a
belt-driven blade being pretty lite.
And actually, a large spring IS the force-provider. Basically you'd have a
mouse-trap type situation, where a very small/fast actuator trips the
spring, which then applies the accelerating force -- one on each side of the
blade could supply wicked fast accelerations.

For example, Lee Spring in NYC has dies springs with spring constants of
over 2,000 # per inch.... and that's just one spring. So these forces are
easily obtainable in very small spaces, more than adequate for even multi-kg
blade housings.

Heh, resetting the blade, tho, would require crowbar.... LOL
But actually, could be done with fine-thread "resetting screw", might take a
cupla minutes.





A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.
==================================================

I suspect the retraction is not for retraction's sake but as a kind of
force
reaction to the stopped blade, preventing more damage than is already
occurring.



From "tired"'s reply it is indeed the saw momentum.
But he seems to imply that it also prevents the injury by
pulling the blade away. We'd have to see a very high-speed
close up of the hot dog video to see the exact sequence
and if the saw stopping alone isn't sufficient.







Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.
================================================== ===

Here's a way to do it:

If a quick retraction occurs over a relatively small distance, AND a
caliper-applied deceleration then occured (non-destructive), you'd have a
more time to stop the blade rotation, ie less demanding braking, no
trashed
blade.

Yes, IF you could retract it quicker than a finger can advance
for as long as it takes to stop the saw.




To wit:
Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a
saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec.
Now, upon the 1/2" retraction, the hand won't contact the blade for
another
50 milliseconds, giving the blade 50x longer to stop, before the hand has
another chance to contact the blade -- a whole lot easier to accomplish
than a 1 millisecond stop.

I suspect the most feasible way to accomplish this kind of retraction is
with bigazz spring (proly two, on either side of the blade, moving two
bearings), triggered much the way the spring of his jamb-ditty is applied,
with the calipers simultaneously engaging.

Heh, and these calipers can act as a brake on the saw during normal use,
as
well, instead of electric motor braking. Lathes often have a frictional
stop system, using a drum-like squeeze brake, very handy.




Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes
the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?
================================================

Mebbe he dudn't drive, or mow his lawn.

Or mebbe just invite me to one of them 'spensive luncheons, where

he's twisting CONgress's arms on safety'n'****, you know, for all the
li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?
===============================================

Like they don't warrant it, right?
These corrupt assholes couldn't give a goddamm about you'n'me, but they
are
surefire quick to up the regulational ante, and then **** the public for
the
slightest transgression. Municipal penalty pricing, donchaknow.
With high enough penalties, they could eliminate taxes, and still remain
in
the black.
--
EA- Hide quoted text -

- Show quoted text -


I've only looked into the SS itself a bit. I haven't looked into
what the inventor is or isn't doing regarding politicians, making
it mandatory, etc.
==================================================

Well, a few replies in the previous thread addressed this, and some forums
have discussed this at length. The almost universal consensus so far is
that his tactics/lobbying, altho legal, are manipulative and greed-driven.
(G)ass is quite at home with the lobbyists..

All's you gotta do is scream Safety loud enough, or " ....the li'l
children...". and BAM, everyfuknthing stops, sense goes out the window, and
you can rip off the system to yer heart's content. Ergo, Crawling Helmets.

I think that whiney asshole TiredofSpam has color-coordinated crawling
helmets, to match his diapers and Superman cape.


Why don't you go back to the little hole you crawled out of. We really
don't need low lifes like you lurking around here. pretty much the only
thing coming out of you is some foul ****, and lots of it. If you ever
had something useful to offer I haven't seen it.
And as for whiney you sack of ****.... all you do is complain... so take
a look in the mirror you penis membrane.

"tiredofspam" nospam.nospam.com wrote in message
...
On 12/8/2012 12:06 PM, Existential Angst wrote:
wrote in message
...
On Dec 8, 10:55 am, "Existential Angst" wrote:
wrote in message

...
On Dec 8, 8:36 am, "Existential Angst" wrote:





There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping
the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more
rapid,
since you would not have to retract the mass of a relatively heavy
motor.
In fact, if designed properly, you could proly have only the blade and
its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably
springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster
process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST,
anyway,
to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started.
========================================

http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1
1:45 the retraction looks pretty complete to me.
BUT, at 2:50, which shows the whole process, it appears that the
retraction
occurs AFTER the collision thingy engages.

Yet, at 1:45, the retraction seem instantaneous, upon touching the hot
dog.... Go figger.

Well, one is normal speed video, the other is high-speed
photography that is slowed down so you can actually
see what is happening.

At the 1:45 normal speed spot all you see is the top of the saw
and it's impossible to determine any sequence of
events. At the 2:50 area it's clear that a substantial amount
of the movement is ocurring after the saw blade has
stopped spinning.

Also, what "tired" just posted makes sense. The saw
has momentum that has to go somewhere. One place
to dissipate it is to allow the blade to go down in a
controlled fashion. It could be that is all they use. If so,
the sequence would be that the pawl engages first
and as it stops the saw, the momentum then causes
the retraction.




And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.
=================================================

10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x
the
weight of a 200# guy.
If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then
it
would only be 200# of force, a lot more manageable.
800# is actually not a cosmically large force, given that some people
can
lift 800#, but it's perhaps a bit to apply in a very small area. And
mebbe
too expensive to implement.

I would expect the mass is more than 2.2 lbs.
And not clear how you'd apply such a large force.
If you used a spring for example, the mass of the spring
also has to be accounted for because you're also
accelerating that.
=============================================

Depends how you design it. I could see a strong magnesium housing to a
belt-driven blade being pretty lite.
And actually, a large spring IS the force-provider. Basically you'd have
a
mouse-trap type situation, where a very small/fast actuator trips the
spring, which then applies the accelerating force -- one on each side of
the
blade could supply wicked fast accelerations.

For example, Lee Spring in NYC has dies springs with spring constants of
over 2,000 # per inch.... and that's just one spring. So these forces
are
easily obtainable in very small spaces, more than adequate for even
multi-kg
blade housings.

Heh, resetting the blade, tho, would require crowbar.... LOL
But actually, could be done with fine-thread "resetting screw", might
take a
cupla minutes.





A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.
==================================================

I suspect the retraction is not for retraction's sake but as a kind of
force
reaction to the stopped blade, preventing more damage than is already
occurring.



From "tired"'s reply it is indeed the saw momentum.
But he seems to imply that it also prevents the injury by
pulling the blade away. We'd have to see a very high-speed
close up of the hot dog video to see the exact sequence
and if the saw stopping alone isn't sufficient.







Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.
================================================== ===

Here's a way to do it:

If a quick retraction occurs over a relatively small distance, AND a
caliper-applied deceleration then occured (non-destructive), you'd have
a
more time to stop the blade rotation, ie less demanding braking, no
trashed
blade.

Yes, IF you could retract it quicker than a finger can advance
for as long as it takes to stop the saw.




To wit:
Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a
saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec.
Now, upon the 1/2" retraction, the hand won't contact the blade for
another
50 milliseconds, giving the blade 50x longer to stop, before the hand
has
another chance to contact the blade -- a whole lot easier to accomplish
than a 1 millisecond stop.

I suspect the most feasible way to accomplish this kind of retraction is
with bigazz spring (proly two, on either side of the blade, moving two
bearings), triggered much the way the spring of his jamb-ditty is
applied,
with the calipers simultaneously engaging.

Heh, and these calipers can act as a brake on the saw during normal use,
as
well, instead of electric motor braking. Lathes often have a frictional
stop system, using a drum-like squeeze brake, very handy.




Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes
the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?
================================================

Mebbe he dudn't drive, or mow his lawn.

Or mebbe just invite me to one of them 'spensive luncheons, where

he's twisting CONgress's arms on safety'n'****, you know, for all the
li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?
===============================================

Like they don't warrant it, right?
These corrupt assholes couldn't give a goddamm about you'n'me, but they
are
surefire quick to up the regulational ante, and then **** the public for
the
slightest transgression. Municipal penalty pricing, donchaknow.
With high enough penalties, they could eliminate taxes, and still remain
in
the black.
--
EA- Hide quoted text -

- Show quoted text -


I've only looked into the SS itself a bit. I haven't looked into
what the inventor is or isn't doing regarding politicians, making
it mandatory, etc.
==================================================

Well, a few replies in the previous thread addressed this, and some
forums
have discussed this at length. The almost universal consensus so far is
that his tactics/lobbying, altho legal, are manipulative and
greed-driven.
(G)ass is quite at home with the lobbyists..

All's you gotta do is scream Safety loud enough, or " ....the li'l
children...". and BAM, everyfuknthing stops, sense goes out the window,
and
you can rip off the system to yer heart's content. Ergo, Crawling
Helmets.

I think that whiney asshole TiredofSpam has color-coordinated crawling
helmets, to match his diapers and Superman cape.


Why don't you go back to the little hole you crawled out of. We really
don't need low lifes like you lurking around here. pretty much the only
thing coming out of you is some foul ****, and lots of it. If you ever had
something useful to offer I haven't seen it.
And as for whiney you sack of ****.... all you do is complain... so take a
look in the mirror you penis membrane.


Methinks you donned that crawling helmet a little too late in your doddering
career.....
Stay away from sharp cornered tables, ok?
--
EA

"tiredofspam" nospam.nospam.com wrote in message
...
On 12/8/2012 9:56 AM, wrote:
On Dec 8, 8:36 am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of
translation, and of rotation, ie, retracting the blade, and stopping the
rotation.

It seems to me one would be sufficient, with retraction having the
advantage
of being non-destructive. Not sure if the blade is direct drive or belt
drive, but if it was belt drive, the retraction could all the more
rapid,
since you would not have to retract the mass of a relatively heavy
motor.
In fact, if designed properly, you could proly have only the blade and
its
bearing retract, along grooved guides of some sort, allowing for a very
rapid acceleration from whatever force is applied -- presumably springs?
But could also be pneumatic or hydraulic, or solenoidal.

Unless the deceleration of rotation is just an inherently faster process
than the retraction process.
But, from what I see, it seems the retraction is occurring FIRST,
anyway, to
initiate the destructive crash, so mebbe the rotational issue is
irrelevant??

In the videos I've seen the blade is fully stopped, while
the retraction is only partial, more like the retraction
has only started. And I think one problem with relying only
on retraction would be that it's not going to be fast
enough to get all or enough of the blade out of the way.
You could do the math and find the force necessary
to move a given mass several inches in 1ms.

A side question is why have the retraction at all.
I guess if you're flopping a whole arm down on the
saw, it would prevent injury from just hitting a stopped
blade.



Now, if rotation is still an issue, wouldn't a caliper/rotor brake type
deal
be as fast as his collision process, AND be non-destructive? Mebbe
multiple
calipers.

It would have to be one hell of a caliper brake to stop that
spinning saw in 1ms. With the way it's implemented now,
at first contact of the jamb the saw is stopped dead.



Oh, oh, but then he wouldn't be able to sell new crumple ditties at
$70/pop.....

Mebbe you could run this by (G)ass, ask him to send me $5 if he likes
the
idears.

You really think he didn't think of a simple brake,
like they have on say lawn mowers, first?




Or mebbe just invite me to one of them 'spensive luncheons, where
he's twisting CONgress's arms on safety'n'****, you know, for all the
li'l
children....
--
EA

Or better yet that anyone involved in this is interested in
answering your questions, given all the insults and names
you've called them?


Maybe if you two watched the video you'd understand.
The blade is stopped, and that is actually part of the retraction
mechanism. The inertia is dissipated by retracting.
The retracting saves the finger as well since it is pulling away from the
finger.


I've seen the actual patent, IIRC...

I can't remember the details about the sensing mechanism...but...

A block of aluminum acts as a brake, effectively stopping the blade dead in
it's tracks by more or less directly engaging six teeth or more all at the
same time (depending on blade pitch) which equates to maybe 10 degrees of
rotation...

--if you do the math, what you'll find is that you'd have to be moving your
finger into the blade at speeds that are simply not humanly possible in
order to do anything more than to draw a very slight amount of blood.

Kind of like the bullet that you never heard...


The design as it stands is very good, your ideas are not.
BTW this is a top notch saw, so no it is not direct drive.
The workmanship on all of these saws exceeds what we now currently have
from the standard non-euro options.

"Leon" lcb11211@swbelldotnet wrote in message
...
On 12/8/2012 6:47 PM, vonKevin wrote:
Leon lcb11211@swbelldotnet wrote:

On 12/8/2012 11:36 AM, scritch wrote:
Alls I know is, having cut my finger nearly in half (still got it,
though) is that I'll be buying a Sawstop saw as soon as I get a 240V
circuit added to my garage. The electrical guy comes next Tuesday.


There are those the believe that they are too careful and or smart to
benefit from a SawStop and will refuse to get one in spite of Gass.

There are those that are careful and smart that have had a serious
injury and will one day buy a SawStop as they now are even more smarter
and more careful because they now have first hand knowledge of how the
unforeseen can get you.

I cut half my thumb off 23 years ago, unfortunately long before the
SawStop became a reality.


Then there are those who are careful and smart, yet have still managed
to have some kind of (albeit minor, in my case) injury, and would love
to have a gadget like this....but refuse to knuckle under to Gass'
thug-like tactics & are waiting patiently for a competitor's product.


-Kevin in Indy
To reply, remove (+spamproof+) from address........


Those people are the ones that will cut off their nose to spite their
faces, can't see the forest for the trees, know better but will continue
to take risks.

No, itsa a li'l thing called "principle".... or "principal" if you're
TiredAss, still looking for de liberry.
Learn how to use push/pull sticks, you won't need (G)ass's hand in yer
ass/wallet.
Altho that all may be moot if (G)ass gets his legislative way.
Or mute, if yer TiredAss....

And another li'l thing called Learning How to Think.

Now, iffin itsa school or some production facility, OK, sawstop away.
But actually, even in the production facility, fixtures can be *easily* made
so that it is pert-near impossible to get hurt during production. And these
fixtures would almost invariably speed production, so it's not like they are
"wasted" on safety issues only. Think HD RAS.

So really, the sawstop has only ONE market with any real merit, the school
market.
Oh, yeah, and the diy-er who insists on watching Atlanta Housewives whilst
using power tools.

There are other table saw solutions as well, which are almost obvious, given
laser/pyooter capabilities.
One is to define the volume/coordinates of the protruding blade, AND the
work at hand. Any other geometric form approaching the blade -- like
fingers, limbs -- would set off a proximity alarm whose loudness is
proportional to the proximity -- which could be user-defined, along with the
limits. And which could non-destructively just power down the saw past
defined limits.

Also, better designed tables, with guides that constrain the work in Z, with
push-stick cutouts -- think of a sheet of plate covering the work, with a
blade shroud -- would actually make for better cuts, radically reduced
kickback, as well as radically improved safety overall.

So (G)ass's solution, like most "solutions" today, are actually the
dumbing-down of the user, an insult to the user, a direct consequence of our
new Point'n'Click Culture.

What, we should ackshooly have to THINK today???

There is another un-intended consequence of this Non-Thinking Solution.
The Table Saw is, in fact, a perty fiersome power tool.
So what happens when you "learn" to use it with some impunity, because you
now "depend" on some hot-dog safety of an instantaneously stopping blade?
Well not much iffin yer using *only* a table saw.

So what happens when you now handle the circular saw, RAS, chain saws, band
saws, lathes, mills, etc. Or even an ax?
NOW, there is *absolutely* some "cognitive disconnect" amongst the various
strategies and perceptions/interpretations of danger/safety, instead of one
uniform response of, well, a controlled fear, focused awareness, intelligent
technique.

It's like these fukn red light cameras:
You now a few trade broad-side impacts with lotsa rear-end impacts.
And you can bet dollars to donuts that the stats of broad-side impacts were
grossly inflated to justify the penalty-pricing revenue-raising
****-the-public-in-the-ass policy of red light cameras.....
When there were/are so many BETTER non-penalty solutions.

Related Digression on the Sodomy of Le Public

Heh, I went to one of our many community/precinct meetings, where the
pohleece dept and council assholes fellate the community for a cupla hours,
and then go back to do-nothingness and corruption as usual.

Well, in this recent meeting, in the name of safety safety safety -- and of
course for the li'l children as well -- the precinct captain was crowing
about how his peeple will leave notes'n'**** on "unsafe cars", with gps
items, phones, etc left in view....
Indeed, how nice and thoughtful, eh?? Saves a lotta bustid windows, theft,
etc.

So Moi raised his tiny li'l hand and meekly observerd,
Heh, yeah, well, dat's real nice'n'thoughtful....... Too bad you
mutha****as don't do that for expired inspections and registrations, eh?

Some appreciative grumblings in the audience, but not much else.... Heh, I
hope I don't need 911 anytime soon....

Talk about ****-the-public-in-the-ass penalty-pricing..... in NYS, this
expired inspection/registration **** amounts to BILLIONS of dollars out of
the pockets of people who can least afford it.

Yeah, I know, TiredAss and few others with sawdust for brains can't see the
connection, but IF they could see past their browned-noses, they'd realize
this is ALL a part of the same
dumb-down-the-Pubic-so's-you-can-more-completely-****-them-in-the-ass public
policies.

While the REAL dangers -- such as assholes spending 4 hours with 150 decibel
leaf blowers, blowing ONE fukn leaf all over their **** properties -- remain
unaddressed.

I'll bet TiredAss is amongst dat bevy of assholes that now believes dead
leaves are toxic, filled with mercury.....
--
EA