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.