On 10/14/10 1:09 PM, Bill wrote:
On 10/14/2010 1:47 PM, -MIKE- wrote:
The problem with me sharing something about this is that someone might
(conceivably, if they had been drinking, perhaps...) think I know what
I'm talking about. I was just thinking about all of the bicycles I've
seen that had a brake pad on just one side...


That is a completely irrelevant comparison.

Look at the forces involved.
A bicycle brake is dealing with what I might speculate to be 1000x the
force.
200lbs at 25+mph is a lot momentum and those little pads do quite a good
job at it.

A coasting 10" saw blade along with whatever mass is added to it by the
arbor assembly is stopped in a couple seconds by light pressure applied
to the side of the blade with a 1cc section of mdf.
I do it all the time. I could probably use my finger.

Try stopping a bike going down hill with that little piece of mdf
pressed lightly against the wheel. Won't happen. :-)


It couldn't be any good for the bearings (on the motor on the TS), huh?

Bill

The arbor on my Delta is a pretty massive item. In another post, I
stated that I would put the pad closer to the arbor, *just in case.*
However, the arbor bearings that couldn't handle the little amount of
pressure it would take to slow down a coasting saw blade wouldn't last
very long on a table saw in its normal operation.

Grinding wheel arbors and extensions don't seem to be affected by forces
much, much greater than what I've considering.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 10/14/2010 1:11 PM, Bill wrote:
On 10/14/2010 1:47 PM, -MIKE- wrote:
On 10/14/10 11:58 AM, Bill wrote:
On 10/14/2010 12:44 PM, -MIKE- wrote:
On 10/14/10 11:17 AM, Bill wrote:
On 10/14/2010 12:15 PM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into
the
wild blue yonder is the issue of getting the blade onto the arbor in
the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow
the
calipers to drop out of the way) would allow enough clearance to get
the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one
pad on the arbor side of the blade would be sufficient for a
convenience
slow/stop.

Maybe so, but that sounds like asking for trouble!

Bill

How? Really. :-)


I'll defer to your wisdom and experience which is surely more vast than
mine. My limited experience and intuition tells me "something is wrong
in that picture"... : )

Bill


And here I thought usenet for was for sharing ideas and learning from
one another.
How silly of me.


I read this on the Internet:
... avoid unnecessary stress on the motor or arbor bearings.

Bill

Now you're reading this on the internet, which also makes it true:

The force applied to the blade near the arbor by a small bicycle brake caliper
is going to be far less stressful on the arbor bearings than some gnarly nasty
piece of wood that's twisting into the blade at the outer perimeter while
you're trying to cut it. When you have a piece of wood that's binding on the
blade and you cut power to the motor, think of how little time it actually
takes for the blade to stop. What, a second or two maybe? That's all I would
be asking for in a convenience brake; to stop the blade within a second or two,
rather than the 10 or 15 seconds (or longer on some saws) it takes for the
blade to stop by itself, and it's not going to take that much pressure to get
it done. And as you've also read on the internet, it's pretty common practice
for people to stop the blade by shoving a piece of wood up against it from the
side; I'd imagine that would also put more stress on the arbor bearings than an
inboard brake caliper.

--
"Even if your wife is happy but you're unhappy, you're still happier
than you'd be if you were happy and your wife was unhappy." - Red Green
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On Thu, 14 Oct 2010 08:52:30 -0400, "Mike Marlow"
wrote:

Steve Turner wrote:


Another reality check for all the people taking this thread off into
the wild blue yonder is the issue of getting the blade onto the arbor
in the presence of calipers that grip either side of the blade. My
interest (and Mike's as well, I think) in using a bicycle brake was
simply a matter of "how can I retrofit my existing table saw with a
simple convenience brake?" I think the wide-opening jaws of a
bicycle brake (maybe along with some kind of front-side cable
disconnect to allow the calipers to drop out of the way) would allow
enough clearance to get the blade on the arbor without too much
trouble. This heavy-duty automotive caliber Saw-Stop alternative
that everybody else is talking about would also have to provide a
similar mechanism, which would of course add to the complexity.

It would be quite easy to mount the caliper on a pivoting mount that would
allow it to swing out of the way for changing blades.
Adding the necessity of an interlock switch so you could not forget
to reposition it and still run the saw ----
More complexity = less reliability.

On Thu, 14 Oct 2010 11:44:16 -0500, -MIKE-
wrote:

On 10/14/10 11:17 AM, Bill wrote:
On 10/14/2010 12:15 PM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into the
wild blue yonder is the issue of getting the blade onto the arbor in the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow the
calipers to drop out of the way) would allow enough clearance to get the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one
pad on the arbor side of the blade would be sufficient for a convenience
slow/stop.

Maybe so, but that sounds like asking for trouble!

Bill

How? Really. :-)
You NEVER put side loads on a saw blade , particularly when running
at speed.

On Thu, 14 Oct 2010 11:27:20 -0500, Steve Turner
wrote:

On 10/14/2010 11:15 AM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into the
wild blue yonder is the issue of getting the blade onto the arbor in the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow the
calipers to drop out of the way) would allow enough clearance to get the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one pad on
the arbor side of the blade would be sufficient for a convenience slow/stop.

That very well could be true, and you could also use such a brake with dado
blades of any thickness... Interesting observation there Mike; I'm gonna have
to go do some peeking inside my Unisaw to see what the possibilities are. :-)
If you want to put a friction brake on a saw blade you need to do it
on the "non-blade" side of the arbour. Put the brake on the pulley if
belt drive, or the "fan end" of the motor if direct drive.

The only problem there is, if you stop the arbour too quickly the
arbour nut will wind off as the blade trys to keep spinning.
Same thing happens if DC injection on ann AC motor or
resistive(regenerative) braking on a DC motor is too harsh..

That's why the "saw stop" HAS to stop the blade directly. Stopping the
blade that fast through the arbour would inevitably wind the blade off
the arbour before the blade came to a safe stop.

On Thu, 14 Oct 2010 11:57:58 -0500, Steve Turner
wrote:

On 10/14/2010 11:47 AM, -MIKE- wrote:
On 10/14/10 11:27 AM, Steve Turner wrote:
On 10/14/2010 11:15 AM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into the
wild blue yonder is the issue of getting the blade onto the arbor in the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow the
calipers to drop out of the way) would allow enough clearance to get the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one
pad on
the arbor side of the blade would be sufficient for a convenience
slow/stop.

That very well could be true, and you could also use such a brake with
dado blades of any thickness... Interesting observation there Mike; I'm
gonna have to go do some peeking inside my Unisaw to see what the
possibilities are. :-)


Good. It's about time that happens to someone *else.*
Let me know what you come up with so I can take credit for it. :-)

Well, peek I did, but it seems the opportunities for mounting such a device, on
the Unisaw at least, are virtually nil. There are just too many clearance
problems to overcome. However, it does seem possible that I could mount a thin
disc to the motor pulley (one that's a couple of inches larger in diameter) and
apply caliper pressure to that instead.

Like I said.

The calipers would have to be mounted
to a bracket that attaches to the motor housing, but that shouldn't be too hard
to accomplish.

On 10/14/2010 2:30 PM, wrote:
On Thu, 14 Oct 2010 11:57:58 -0500, Steve Turner
wrote:

On 10/14/2010 11:47 AM, -MIKE- wrote:
On 10/14/10 11:27 AM, Steve Turner wrote:
On 10/14/2010 11:15 AM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into the
wild blue yonder is the issue of getting the blade onto the arbor in the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow the
calipers to drop out of the way) would allow enough clearance to get the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one
pad on
the arbor side of the blade would be sufficient for a convenience
slow/stop.

That very well could be true, and you could also use such a brake with
dado blades of any thickness... Interesting observation there Mike; I'm
gonna have to go do some peeking inside my Unisaw to see what the
possibilities are. :-)


Good. It's about time that happens to someone *else.*
Let me know what you come up with so I can take credit for it. :-)

Well, peek I did, but it seems the opportunities for mounting such a device, on
the Unisaw at least, are virtually nil. There are just too many clearance
problems to overcome. However, it does seem possible that I could mount a thin
disc to the motor pulley (one that's a couple of inches larger in diameter) and
apply caliper pressure to that instead.

Like I said.

After I already said it.

--
See Nad. See Nad go. Go Nad!
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
wrote:

wrote:
On Wed, 13 Oct 2010 22:52:34 -0400, "Josepi"
wrote:

As I stated posters seem to lean towards the technology they are
comfortable with.

The mechanics would be a nightmare to me, also. To others the
electronics would be a nightmare.

Contactor and resistor?...way too complicated.


wrote in message
...
You want to put that monstrosity on a tilting arbour saw, mounted
under the saw table and in the path of the saw-dust and have it work
reliably???
Not going to happen - guaranteed.

It's BECAUSE I was a mechanic for several decades that I would NOT use
a brake caliper for the application.

As a guy who has done all of his own vehicle maintenance for 40 years now, I
have to ask what you observed in your experiences, that causes you to make
this statement? I don't know if the brake caliper idea is the most elegant
solution, but I sure can't see anything in what you are saying that would
suggest it is not a workable solution.


First of all, it's just too big and heavy to fit. Second it's using an
atom bomb to swat a fly. Third, it's too complex. Exactly haw are you
going to actuate it?????
Forth, how are you going to get it out of the way to change blades?
Fifth - How are you going to compensate for different blade
thicknesses - or heaven help you, a DADO blade?
Also, single piston or dual piston? and how are you going to ensure
the pressure on both sides of the blade is equal, and application is
even.. Push on one side of the blade more than the other and the blade
goes into an oscillation/wobble and you eventually break the web out
of the blade. Then you have a REAL safety issue!!!!!.

Trust me - it's a BAD idea - and almost totally unworkable on so MANY
levels if you understand anything about how both the saw and the break
caliper work.

In article ,



A car wheel spinning at 5000RPM's isn't stopped within a single rotation
by a caliper disc brake. Why would you expect a saw blade to be?

On an average wheel, that would be 330+ mph (Or therabouts ± 50 mph)

I don't think you'd want to stop that tire in one rotation. G

On Thu, 14 Oct 2010 06:08:55 -0700, Larry Jaques
wrote:

On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
wrote:

wrote:
On Wed, 13 Oct 2010 22:52:34 -0400, "Josepi"
wrote:

As I stated posters seem to lean towards the technology they are
comfortable with.

The mechanics would be a nightmare to me, also. To others the
electronics would be a nightmare.

Contactor and resistor?...way too complicated.


wrote in message
...
You want to put that monstrosity on a tilting arbour saw, mounted
under the saw table and in the path of the saw-dust and have it work
reliably???
Not going to happen - guaranteed.

It's BECAUSE I was a mechanic for several decades that I would NOT use
a brake caliper for the application.

As a guy who has done all of his own vehicle maintenance for 40 years now, I
have to ask what you observed in your experiences, that causes you to make
this statement? I don't know if the brake caliper idea is the most elegant
solution, but I sure can't see anything in what you are saying that would
suggest it is not a workable solution.

Suitable placement of an air nozzle tube to clear the caliper frame
every hour or so would go far into making this device work for more
than an hour. You'd have to keep the sawdust from piercing the seals
and/or building up on the frame
Which just adds more complexity, reducing the reliability beyond the
acceptable (at least for mr) level.

On 10/14/2010 2:29 PM, wrote:
On Thu, 14 Oct 2010 11:27:20 -0500, Steve Turner
wrote:

On 10/14/2010 11:15 AM, -MIKE- wrote:
On 10/14/10 6:39 AM, Steve Turner wrote:
Another reality check for all the people taking this thread off into the
wild blue yonder is the issue of getting the blade onto the arbor in the
presence of calipers that grip either side of the blade. My interest
(and Mike's as well, I think) in using a bicycle brake was simply a
matter of "how can I retrofit my existing table saw with a simple
convenience brake?" I think the wide-opening jaws of a bicycle brake
(maybe along with some kind of front-side cable disconnect to allow the
calipers to drop out of the way) would allow enough clearance to get the
blade on the arbor without too much trouble.

Heck, I think if it was mounted closer to the arbor than the edge, one pad on
the arbor side of the blade would be sufficient for a convenience slow/stop.

That very well could be true, and you could also use such a brake with dado
blades of any thickness... Interesting observation there Mike; I'm gonna have
to go do some peeking inside my Unisaw to see what the possibilities are. :-)
If you want to put a friction brake on a saw blade you need to do it
on the "non-blade" side of the arbour. Put the brake on the pulley if
belt drive, or the "fan end" of the motor if direct drive.

The only problem there is, if you stop the arbour too quickly the
arbour nut will wind off as the blade trys to keep spinning.
Same thing happens if DC injection on ann AC motor or
resistive(regenerative) braking on a DC motor is too harsh..

That's why the "saw stop" HAS to stop the blade directly. Stopping the
blade that fast through the arbour would inevitably wind the blade off
the arbour before the blade came to a safe stop.

Valid point, but again, we're not talking about a Saw-Stop equivalent here,
only a "convenience" brake that stops the blade in a second or two. Unless
you've dangerously under-tightened the arbor nut (or ridiculously
over-engineered the brake) that's not likely to cause enough centrifugal force
to loosen the arbor nut.

--
Any given amount of traffic flow, no matter how
sparse, will expand to fill all available lanes.
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On Thu, 14 Oct 2010 09:27:45 -0400, "Mike Marlow"
wrote:

Larry Jaques wrote:
On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
wrote:


As a guy who has done all of his own vehicle maintenance for 40
years now, I have to ask what you observed in your experiences, that
causes you to make this statement? I don't know if the brake
caliper idea is the most elegant solution, but I sure can't see
anything in what you are saying that would suggest it is not a
workable solution.

Suitable placement of an air nozzle tube to clear the caliper frame
every hour or so would go far into making this device work for more
than an hour. You'd have to keep the sawdust from piercing the seals
and/or building up on the frame

Not at all Larry, if you consider what a normal brake caliper in an
automobile is subject to. In comparison, the environment inside a table saw
would be a walk in the part of a caliper.


You get a splinter of oak thrown at a rubber caliper boot at 18000
feet per minute (almost 205MPH) a few times and expect the boot to
survive?. For the brake to see the same rotational RPM on a car with
24" diameter tires (pretty standard today) you would need to drive
over 250 MPH. Closer to 260MPH if the saw runs 3650 RPM.

A 10" saw runs closer to 5200 RPM - so 370 MPH.

Also, the caliper is actually pretty well protected mounted as it is
virtually inside the wheel - with the caliper boot protected between
the pad and tha caliper frame, and usually behind a splash shield as
well.

Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

On Thu, 14 Oct 2010 08:27:07 -0400, "J. Clarke"
wrote:

In article ,
says...

On Wed, 13 Oct 2010 23:15:27 -0400, "J. Clarke"
wrote:

In article ,
says...

On Wed, 13 Oct 2010 18:15:40 -0400, "J. Clarke"
wrote:

In article ,
says...

On Tue, 12 Oct 2010 22:25:50 -0400, "J. Clarke"
wrote:

In article ,
says...

On Mon, 11 Oct 2010 19:59:30 -0400, Bill wrote:

J. Clarke wrote:
In , says...

I would think that an emergency stop mechanism would be a whole different
magnitude than a scheduled, everyday, stop.

For a finger saver an emergency stop mechanism would have to stop the blade
in a few teeth passings. For everyday usage a couple dozen blade rotations
would be OK too. These two situations would require different tactics.

A dynamic electronic brake could vary the intensity for the two different
scenarios and we could add the caliper to the emerg stop. A caliper probably
wouldn't last long in everyday usage and would need to be adjusted and/or
replaced frequently.

So how much power do you have to put into that electronic brake to stop
the blade as fast as Sawstop's physical block?

And why would a caliper not last long? A set of brake pads on a car
with 10" rotors lasts 40,000 miles or so, and they're getting a Hell of
a lot more of a workout that they would stopping a little bitty saw
blade that masses less than 1/1000 as much.

The physics on that seem interesting. A little like stopping a speeding
bullet on a dime--it challenges my imagination. Probably not quite as
difficult as stopping a lightning bolt, but I wouldn't want to try that
either.

Bill
No way a caliper could stop the blade in even 4X the time the
saw-stop does. And keeping dust out of the gap between tha "pad" and
the blade would be quite problematic - with dust decreasing the
stopping efficiency by a very large margin.

I suspect that a small pyrotechnic pressurizing one of the calipers off
my '76 Lincoln might surprise you.

But would also be totally impractical on a 10" saw.

Why would it be "impractical on a 10" saw? The brake rotors on that car
are IIRC 11.5 inch diameter and the whole brake assembly fits inside a
15" wheel.

You want to put that monstrosity on a tilting arbour saw, mounted
under the saw table and in the path of the saw-dust and have it work
reliably???
Not going to happen - guaranteed.

It works reliably on a tilting Lincoln wheel in the path of rain, road
dust, and whatever else mother nature can throw at it, so why does a
nice, dry saw cabinet present such problems?

Do yourself a favor, pull a wheel off your car and _look_ at the
mechanism.

I've been doing it for over 45 years
I've also rebuilt a few tilting arbour saws - both belt drive, gear
drive, and direct drive..

And yet you see a problem.

Most definitely.

On 10/14/10 2:24 PM, wrote:

How? Really. :-)
You NEVER put side loads on a saw blade , particularly when running
at speed.

1. It wouldn't be running.
2. What I'm talking about could hardly be considered a load.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 10/14/10 2:29 PM, wrote:
On Thu, 14 Oct 2010 11:27:20 -0500, Steve Turner
The only problem there is, if you stop the arbour too quickly the
arbour nut will wind off as the blade trys to keep spinning.
Same thing happens if DC injection on ann AC motor or
resistive(regenerative) braking on a DC motor is too harsh..


Neither of us is trying to stop the blade that fast.


That's why the "saw stop" HAS to stop the blade directly. Stopping the
blade that fast through the arbour would inevitably wind the blade off
the arbour before the blade came to a safe stop.

I seriously doubt that was even the slightest consideration for the
inventor of the SawStop.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On Thu, 14 Oct 2010 10:58:43 -0700 (PDT), Robatoy
wrote:

I propose an air bag. Electronically triggered, it throws you
backwards across the shop and away from the table saw. Punches you
right in the chest with the option for a double bag for some people
here in which case the second bag knocks some sense in them. We can
glue on a boxing glove for that operation...just a 4 oz. one; you want
it to hurt a little.
One can mount the boxing glove on an expanding multi-pivot articulated
parallelogram.
What a stellar idea.
I'm talking to investors now.
They want to call the company ACME.

Would make a great cartoon to pass about the Internet, if twas done in
animation might even go viral. But you might want to have a huge
catchers mitt behind the punchee.

Mark

"Markem" wrote in message
news
On Thu, 14 Oct 2010 10:58:43 -0700 (PDT), Robatoy
wrote:

I propose an air bag. Electronically triggered, it throws you
backwards across the shop and away from the table saw. Punches you
right in the chest with the option for a double bag for some people
here in which case the second bag knocks some sense in them. We can
glue on a boxing glove for that operation...just a 4 oz. one; you want
it to hurt a little.
One can mount the boxing glove on an expanding multi-pivot articulated
parallelogram.
What a stellar idea.
I'm talking to investors now.
They want to call the company ACME.

Would make a great cartoon to pass about the Internet, if twas done in
animation might even go viral. But you might want to have a huge
catchers mitt behind the punchee.

Is Wiley Coyote available as a spokesperson?

On 10/14/2010 2:52 PM, wrote:
On Thu, 14 Oct 2010 09:27:45 -0400, "Mike Marlow"
wrote:

Larry Jaques wrote:
On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
wrote:


As a guy who has done all of his own vehicle maintenance for 40
years now, I have to ask what you observed in your experiences, that
causes you to make this statement? I don't know if the brake
caliper idea is the most elegant solution, but I sure can't see
anything in what you are saying that would suggest it is not a
workable solution.

Suitable placement of an air nozzle tube to clear the caliper frame
every hour or so would go far into making this device work for more
than an hour. You'd have to keep the sawdust from piercing the seals
and/or building up on the frame

Not at all Larry, if you consider what a normal brake caliper in an
automobile is subject to. In comparison, the environment inside a table saw
would be a walk in the part of a caliper.


You get a splinter of oak thrown at a rubber caliper boot at 18000
feet per minute (almost 205MPH) a few times and expect the boot to
survive?. For the brake to see the same rotational RPM on a car with
24" diameter tires (pretty standard today) you would need to drive
over 250 MPH. Closer to 260MPH if the saw runs 3650 RPM.

A 10" saw runs closer to 5200 RPM - so 370 MPH.

Ever heard of "mass"? By your logic, my Dremel tool running at 30,000 RPM
would be even more impossible to stop.

Also, the caliper is actually pretty well protected mounted as it is
virtually inside the wheel - with the caliper boot protected between
the pad and tha caliper frame, and usually behind a splash shield as
well.

Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

Geez Chicken Little, how many mountains are you going to make out of molehills
on this topic? Just about every point you've tried to make has had the air of
doom, disaster, and failure. This ain't that friggin' difficult, Penelope.

--
See Nad. See Nad go. Go Nad!
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On 10/14/10 4:22 PM, Steve Turner wrote:
Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

Geez Chicken Little, how many mountains are you going to make out of
molehills on this topic? Just about every point you've tried to make has
had the air of doom, disaster, and failure. This ain't that friggin'
difficult, Penelope.


And since when is Oak sawdust corrosive... no, I'm sorry..."VERY
CORROSIVE?"

I saw my fair amount of oak and I'm not exactly a neat guy in the shop.
I clean up my saw dust when it ****es me off enough, which is usually
when it's in the way of the next project, which means, it can sit around
under the saw, on my tools, all kinds of other metal, plastic, and
rubber stuff, including the end of this run-on sentence, for months at a
time.

I haven't seen it corrode a single thing.
(This should cue some pseudo scientific diatribe about some oil in oak,
contained in a minuscule amout, which is technically an acid or oxidizer
of some sort which *can* corrode *something* on planet earth.)


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

In article ,
wrote:


Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

More corrosive than road salt?

On 10/14/10 5:06 PM, Robatoy wrote:
In ,
wrote:


Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

More corrosive than road salt?

More corrosive than brake fluid? Because calipers neeeeeever leak.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

Spoken like a true woodworker...LOL


"J. Clarke" wrote in message
in.local...
C-clamp.




In article ,
says...

On 10/13/2010 02:32 PM, J. Clarke wrote:
In ,
says...

On 10/13/10 9:43 AM, J. Clarke wrote:
In , says...

J. Clarke wrote:
In , says...

J. Clarke wrote:
In ,
says...

On Mon, 11 Oct 2010 19:59:30 -0400,
wrote:

J. Clarke wrote:
In ,
says...

I would think that an emergency stop mechanism would be a
whole different
magnitude than a scheduled, everyday, stop.

For a finger saver an emergency stop mechanism would have to
stop the blade
in a few teeth passings. For everyday usage a couple dozen
blade rotations
would be OK too. These two situations would require different
tactics.

A dynamic electronic brake could vary the intensity for the
two different
scenarios and we could add the caliper to the emerg stop. A
caliper probably
wouldn't last long in everyday usage and would need to be
adjusted and/or
replaced frequently.

So how much power do you have to put into that electronic brake
to stop
the blade as fast as Sawstop's physical block?

And why would a caliper not last long? A set of brake pads on
a car
with 10" rotors lasts 40,000 miles or so, and they're getting a
Hell of
a lot more of a workout that they would stopping a little bitty
saw
blade that masses less than 1/1000 as much.

The physics on that seem interesting. A little like stopping a
speeding
bullet on a dime--it challenges my imagination. Probably not
quite as
difficult as stopping a lightning bolt, but I wouldn't want to
try that
either.

Bill
No way a caliper could stop the blade in even 4X the time
the
saw-stop does. And keeping dust out of the gap between tha "pad"
and
the blade would be quite problematic - with dust decreasing the
stopping efficiency by a very large margin.

I suspect that a small pyrotechnic pressurizing one of the calipers
off
my '76 Lincoln might surprise you.


When it snapped (seriously)? I'm not an engineer, so I don't know
for
sure. I just wouldn't be surprised. Maybe someone else can opine.

Why would something that can stop a 4000 pound car "snap" when
called on
to stop a 3 pound saw blade?

"Pyrotechnics" rather than a master cylinder with brake fluid?

To stop the saw in a fraction of a revolution, you need rapid
application. A pyro will build pressure rapidly.

I didn't think we were talking about an emergency stop.
AFAIK, we're discussing a convenience stop which, in my opinion, would
be satisfactorily done in a couple seconds, not milliseconds.

Well, geez, for that a bicycle brake will work fine.

Another reality check for all the people taking this thread off into the
wild blue yonder is
the issue of getting the blade onto the arbor in the presence of calipers
that grip either
side of the blade. My interest (and Mike's as well, I think) in using a
bicycle brake was
simply a matter of "how can I retrofit my existing table saw with a simple
convenience
brake?" I think the wide-opening jaws of a bicycle brake (maybe along
with some kind of
front-side cable disconnect to allow the calipers to drop out of the way)
would allow enough
clearance to get the blade on the arbor without too much trouble. This
heavy-duty
automotive caliber Saw-Stop alternative that everybody else is talking
about would also have
to provide a similar mechanism, which would of course add to the
complexity.

That happens freuently to my Milwalkee 12V drill. The brake stops the
insides but the chuck wants to keep on going and undoes itself and the bit
falls out. The chuck even appears to have a dual gear ratio tightening
mechanism.


"Steve Turner" wrote in message
...
Valid point, but again, we're not talking about a Saw-Stop equivalent here,
only a "convenience" brake that stops the blade in a second or two. Unless
you've dangerously under-tightened the arbor nut (or ridiculously
over-engineered the brake) that's not likely to cause enough centrifugal
force
to loosen the arbor nut.

--
Any given amount of traffic flow, no matter how
sparse, will expand to fill all available lanes.
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On Thu, 14 Oct 2010 15:09:44 -0500, -MIKE-
wrote:

On 10/14/10 2:29 PM, wrote:
On Thu, 14 Oct 2010 11:27:20 -0500, Steve Turner
The only problem there is, if you stop the arbour too quickly the
arbour nut will wind off as the blade trys to keep spinning.
Same thing happens if DC injection on ann AC motor or
resistive(regenerative) braking on a DC motor is too harsh..


Neither of us is trying to stop the blade that fast.


That's why the "saw stop" HAS to stop the blade directly. Stopping the
blade that fast through the arbour would inevitably wind the blade off
the arbour before the blade came to a safe stop.

I seriously doubt that was even the slightest consideration for the
inventor of the SawStop.
From what I was told it WAS.

OMG! Now we need to put an ABS system on our saw brake so it doesn't cause
any arbor damge from stopping to quickly?

LOL


"Scott Lurndal" wrote in message
...
On the other hand, disc brakes are designed so they don't lock up,
this includes the materials used as well plus the modern ABS electronics.

scott



"HeyBub" writes:
wrote:
This is all assuming a clean blade for the proper high co-efficient
of friction.
Dust od sap build-up on the blade can change that very quickly.

Consider what a disk brake caliper has to overcome: dirt, water, oil,
pigeons. It still does a pretty good job.

I have no idea what EU regulations state or why they would care about a
gradual stop of a saw blade.

Are these regulations involved in convenience stopping of a table saw blade
and what do they state?


"J. Clarke" wrote in message
in.local...
If it "works like a charm" then why can't it slow a dado fast enough to
meet EU regulations?



In article , says...

The electornic way would be so much gentler and easier to implement. They
work like a charm.

Maybe only because of the background of the guys proposing it.

Maybe not. Somebody has to take one for the team. Induction motors typically
have enough back emf generation to cause some, if not enough braking to stop
most motors.

Somebody try it. With the saw blade running full speed, pull the plug (do
**NOT** turn off the switch) and stick the two plug contacts (line and
neutral) across the metal table top and short it out.

Tell us what happens and what kind of motor you have.

The DC injection will involve a little more circuitry.

I have experienced both with different motors. They ranged from 1hp AC to
5hp DC units. The DC injection could make them stop in a turn or so but with
such large motors the torque was brutal.


"J. Clarke" wrote in message
.local...
So now you have to add a power supply and controls.


In article ,
says...
On an induction motor the process is a bit different. Instead of aresistor
across the motor to stop it you use "DC Injection" - in other
words throw about 40 volts DC across the winding for about 2 seconds.

On Thu, 14 Oct 2010 16:22:22 -0500, Steve Turner
wrote:

On 10/14/2010 2:52 PM, wrote:
On Thu, 14 Oct 2010 09:27:45 -0400, "Mike Marlow"
wrote:

Larry Jaques wrote:
On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
wrote:


As a guy who has done all of his own vehicle maintenance for 40
years now, I have to ask what you observed in your experiences, that
causes you to make this statement? I don't know if the brake
caliper idea is the most elegant solution, but I sure can't see
anything in what you are saying that would suggest it is not a
workable solution.

Suitable placement of an air nozzle tube to clear the caliper frame
every hour or so would go far into making this device work for more
than an hour. You'd have to keep the sawdust from piercing the seals
and/or building up on the frame

Not at all Larry, if you consider what a normal brake caliper in an
automobile is subject to. In comparison, the environment inside a table saw
would be a walk in the part of a caliper.


You get a splinter of oak thrown at a rubber caliper boot at 18000
feet per minute (almost 205MPH) a few times and expect the boot to
survive?. For the brake to see the same rotational RPM on a car with
24" diameter tires (pretty standard today) you would need to drive
over 250 MPH. Closer to 260MPH if the saw runs 3650 RPM.

A 10" saw runs closer to 5200 RPM - so 370 MPH.

Ever heard of "mass"? By your logic, my Dremel tool running at 30,000 RPM
would be even more impossible to stop.


No, I said nothing of the sort. I didn't even say anything about it
being hard to stop. I was comaring the speed at which particals might
possibly hit the boot on the lincoln caliper some dufus was talking
about mounting to the table saw to stop the blade, The speed at which
a sliver could be flung at that boot from a typical table saw blade
would require the above mentioned speeds with the caliper on a car -
assuming the bit was picked up from the road or thrown from the
circumference of the tire.
Also, the caliper is actually pretty well protected mounted as it is
virtually inside the wheel - with the caliper boot protected between
the pad and tha caliper frame, and usually behind a splash shield as
well.

Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

Geez Chicken Little, how many mountains are you going to make out of molehills
on this topic? Just about every point you've tried to make has had the air of
doom, disaster, and failure. This ain't that friggin' difficult, Penelope.

Nobody said it was difficult. Just saying the brake from the old
lincoln is NOT going to be anywhere close to an effective solution.
So many guys on the Wreck just make things WAY too complicated.

You want a convenience brake on an AC table saw? DC injection braking
is as simple as it gets and can be done by a reasonably adept
scrounger for less than $25 in less than an hour, with NO
modifications to the physical part of the saw. Just grabbing a few
parts out of my scrap bin I could have it working on a saw in less
than half an hour with no cash outlay at all. Not fully automated -
but hit the stop button or turn off the power and press a pushbutton
untill the blade stops (about 2 seconds) using nothing more than an
old PC power supply and a pushbutton switch. To make it a littlemore
foolproof the power switch would need to be replaces with a SPDT or
DPDT switch or augmented by a relay to prevent injecting the DC while
the AC was still connected.

Corrodes the hell out of my sinuses! Usually a bloody nose the next morning
everytime, after Oak...LOL


"-MIKE-" wrote in message
...
And since when is Oak sawdust corrosive... no, I'm sorry..."VERY
CORROSIVE?"

I saw my fair amount of oak and I'm not exactly a neat guy in the shop.
I clean up my saw dust when it ****es me off enough, which is usually
when it's in the way of the next project, which means, it can sit around
under the saw, on my tools, all kinds of other metal, plastic, and
rubber stuff, including the end of this run-on sentence, for months at a
time.

I haven't seen it corrode a single thing.
(This should cue some pseudo scientific diatribe about some oil in oak,
contained in a minuscule amout, which is technically an acid or oxidizer
of some sort which *can* corrode *something* on planet earth.)


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On Thu, 14 Oct 2010 16:38:53 -0500, -MIKE-
wrote:

On 10/14/10 4:22 PM, Steve Turner wrote:
Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

Geez Chicken Little, how many mountains are you going to make out of
molehills on this topic? Just about every point you've tried to make has
had the air of doom, disaster, and failure. This ain't that friggin'
difficult, Penelope.


And since when is Oak sawdust corrosive... no, I'm sorry..."VERY
CORROSIVE?"

Never see the black staining in oak from non-galvanized nails? That is
due to corrosion. Doesn't take much corrosion to make a caliper just
fussy enough that it might not do the required job (for which it was
not designed).

See also:
http://www.scribd.com/doc/36276187/C...Metals-by-Wood

I saw my fair amount of oak and I'm not exactly a neat guy in the shop.
I clean up my saw dust when it ****es me off enough, which is usually
when it's in the way of the next project, which means, it can sit around
under the saw, on my tools, all kinds of other metal, plastic, and
rubber stuff, including the end of this run-on sentence, for months at a
time.

I haven't seen it corrode a single thing.
(This should cue some pseudo scientific diatribe about some oil in oak,
contained in a minuscule amout, which is technically an acid or oxidizer
of some sort which *can* corrode *something* on planet earth.)

How about a compressed air nozzle aimed at the carbide of the blade to slow
it to a stop?

It would clean it off and compressed air is usually available.


wrote in message
...
On Thu, 14 Oct 2010 08:50:21 -0400, "Mike Marlow"
First of all, it's just too big and heavy to fit. Second it's using an
atom bomb to swat a fly. Third, it's too complex. Exactly haw are you
going to actuate it?????
Forth, how are you going to get it out of the way to change blades?
Fifth - How are you going to compensate for different blade
thicknesses - or heaven help you, a DADO blade?
Also, single piston or dual piston? and how are you going to ensure
the pressure on both sides of the blade is equal, and application is
even.. Push on one side of the blade more than the other and the blade
goes into an oscillation/wobble and you eventually break the web out
of the blade. Then you have a REAL safety issue!!!!!.

Trust me - it's a BAD idea - and almost totally unworkable on so MANY
levels if you understand anything about how both the saw and the break
caliper work.

On Thu, 14 Oct 2010 17:26:59 -0500, -MIKE-
wrote:

On 10/14/10 5:06 PM, Robatoy wrote:
In ,
wrote:


Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

More corrosive than road salt?

More corrosive than brake fluid? Because calipers neeeeeever leak.
Brake fluid itself is not corrosive. When it absorbs moisture it is -
and brake fluid is highly hygroscopic.

Nobody wants to stop a saw blade in one rev. Convenience stop only.

This was barked at when the SawStop came into comparison.


"Scott Lurndal" wrote in message
...
A car wheel spinning at 5000RPM's isn't stopped within a single rotation
by a caliper disc brake. Why would you expect a saw blade to be?

A car brake is designed to avoid locking up, yet that's exactly the
behavior you would want with a sawblade, and you'd want it to lock in
much less than a single revolution.

On 10/14/10 6:39 PM, wrote:
Geez Chicken Little, how many mountains are you going to make out of
molehills on this topic? Just about every point you've tried to make has
had the air of doom, disaster, and failure. This ain't that friggin'
difficult, Penelope.


And since when is Oak sawdust corrosive... no, I'm sorry..."VERY
CORROSIVE?"

Never see the black staining in oak from non-galvanized nails? That is
due to corrosion. Doesn't take much corrosion to make a caliper just
fussy enough that it might not do the required job (for which it was
not designed).


Yep, as predicted. :-p


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On 10/14/10 6:40 PM, wrote:
On Thu, 14 Oct 2010 17:26:59 -0500,
wrote:

On 10/14/10 5:06 PM, Robatoy wrote:
In ,
wrote:


Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

More corrosive than road salt?

More corrosive than brake fluid? Because calipers neeeeeever leak.
Brake fluid itself is not corrosive. When it absorbs moisture it is -
and brake fluid is highly hygroscopic.

I guess I was wrong then.
sheesh


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On Oct 14, 7:52*pm, -MIKE- wrote:
On 10/14/10 6:40 PM, wrote:





On Thu, 14 Oct 2010 17:26:59 -0500,
wrote:

On 10/14/10 5:06 PM, Robatoy wrote:
In ,
* wrote:

Then start sawing oak, and leaving the VERY CORROSIVE sawdust caked
onto every surface of the caliper.

More corrosive than road salt?

More corrosive than brake fluid? * *Because calipers neeeeeever leak.
* Brake fluid itself is not corrosive. When it absorbs moisture it is -
and brake fluid is highly hygroscopic.

I guess I was wrong then.
sheesh

what does it feel like, Mike?

Scott Lurndal wrote:


On the other hand, disc brakes are designed so they don't lock up,
this includes the materials used as well plus the modern ABS
electronics.


No they aren't. ABS systems are designed to prevent the wheel from locking
up, but disk brakes aren't. In fact, quite the opposite, they are designed
to lock up but rely upon the ABS to govern them so they don't.

--

-Mike-

Josepi wrote:


A car brake is designed to avoid locking up, yet that's exactly the
behavior you would want with a sawblade, and you'd want it to lock in
much less than a single revolution.

ABS is designed to prevent lock up - car brakes are not.

--

-Mike-

wrote:


First of all, it's just too big and heavy to fit.

Why so? A caliper does not have to be large.

Second it's using an
atom bomb to swat a fly. Third, it's too complex. Exactly haw are you
going to actuate it?????

Too complex? On the contrary, it's very simple.

Forth, how are you going to get it out of the way to change blades?

Well, one idea would be to mount it on the inside of the arbor so that it
does not even have to be removed to replace a blade.

Fifth - How are you going to compensate for different blade
thicknesses - or heaven help you, a DADO blade?

See above answer.

Also, single piston or dual piston?

You are going out of your way to make this appear to be complicated now.

and how are you going to ensure
the pressure on both sides of the blade is equal, and application is
even..

Both sides? Why both sides? For the discussion at hand, one side would be
ample.

Push on one side of the blade more than the other and the blade
goes into an oscillation/wobble and you eventually break the web out
of the blade. Then you have a REAL safety issue!!!!!.

Sure - it you push it hard enough. No need for that level of pressure
though. Think about what forces your blade sees as you cut through a
knarley hunk of hardwood. It sees more lateral force than would be required
for a simple blade brake - which is the discussion at hand.


Trust me - it's a BAD idea - and almost totally unworkable on so MANY
levels if you understand anything about how both the saw and the break
caliper work.

Sorry Clare - cannot trust you on this point. I see it as perfectly
workable and not subject to any of the concerns you've outlined. I do
understand both how the saw works and how calipers work but you have not
argued anything to make the idea impractical.

--

-Mike-

wrote:


Never see the black staining in oak from non-galvanized nails? That is
due to corrosion. Doesn't take much corrosion to make a caliper just
fussy enough that it might not do the required job (for which it was
not designed).


I thought you worked on cars Clare. Have you ever seen a caliper that was
*not corroded*? You're exagerating things in attempt to bolster your point
but again, it's just not true.

--

-Mike-