On 10/15/10 3:14 PM, Steve Turner wrote:
On 10/15/2010 12:36 PM, Josepi wrote:

No big deal. Text mediums get messy after a while.

Yeah, because of idiots like you.


He probably laments leaving webtv. :-)


--

-MIKE-

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

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On 10/15/2010 1:16 PM, wrote:
OK - the whole premise of using a caliper, regardless of the source
of the caliper, for a retrofit to an existing saw has all the
drawbacks I have stated. OK, the corrosion might be a bit overstated -
but it IS an issue that would have to be dealt with -nas it has to be
dealt with in automotive, bicycle, and motorcycle applications. Using
a caliper of any sort on the blade, even on a purpose built clean
sheet saw design has engineering problems that would be best avoided
due to complexity (like blade changing, adjustment for dado use, etc.)
Putting the caliper (or drum) on the opposite end of the arbour
handles most of those issues, but again, on a clean sheet design. As a
retrofit it is still problematic.

That's a blanket statement. I would say that depends on the saw.

Putting the brake on the motor is
the simplest solution - wheather mechanical or electrical, and
wheather direct drive or belt drive.

That's what I concluded after inspecting my saw (the Unisaw). Other saws may
be different.

Either way, electrical application is the simplest, cheapest
alternative (compared to hydraulic, mechanical, pneumatic, or
percussive application) - and if you are going to use electical or
electronic controls anyway, why not use electrical braking all the
way?

In my case, it's because I can understand and implement mechanical devices;
electrical, not so much. If somebody were to implement and test and guarantee
an electrical braking system that could be retrofitted to my Unisaw I would
certainly be interested.

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

I don't recall rejecting yours, I only recall you rejecting mine... In any
case, for the Unisaw I think it would be relatively simple to actuate the brake
with a mechanical lever that's mounted in front of the power-off switch.
Initial pressure on the lever would actuate the power-off switch and cut power
to the motor, additional pressure would actuate the brake. This is exactly the
way the mechanical (automotive style drum) brake on my MiniMax bandsaw works.
And work it does; like a dream, and I can tell you that those upper and lower
drive wheels are about 20lbs apiece and have WAY (*WAY*!) more mass and
centrifugal force than a free-spinning table saw blade assembly.

It is the only virtually universally implementable retrofit or add-on
solution that does not require custom engineering for every saw it
might possibly be applicable to.

A lot of dreamers on the wreck - but how many implementers?

I have every confidence that I can implement a mechanical solution on my
Unisaw, and believe me, the naysayer attitude of a certain few (ahem) has just
about ticked me off enough to follow through with it. My only problem is
carving out the time to get it done; I have precious little of that these days.

So what's stopping YOU from being an implementer?

Also, if electrical convenience braking is such a bad idea, why is it
virtually the ONLY method used on commercially available table saws,
particularly in the "consumer grade", "contractor", or "semi-pro"
lines?

You never heard from *me* that it was a bad idea.

Virtually every hand held circular saw on the market today has a
"dynamic blade brake" as a standard feature as well.
So does virtually every quality cut-off or miter saw.

My 3HP Makita plunge router has one and I love it. So does my Delta chop saw,
but that thing's a piece of crap in most every other respect, so I avoid using
it unless I have to.

Best of all, it COULD be made as a simple plug-in module that you plug
the saw into - replacing the existing power switch, on all but the
higher end saws that use contactors instead of a simple switch.

It could be made offshore, in reasonable quantities, to sell for less
than $50 retail.
It could be implemented, from scratch, by a reasonably competent
tinkerer for under $100 buying all the parts new from local or online
sources, and could be installed on ANY saw. Either as a plug in as
above, or wired directly into the saw. Contacter controlled mabee add
another $50.

I would have zero confidence in doing that unless I was working from plans
offered by another "tinkerer" who had already succeeded and was able to
demonstrate that it worked and was safe and that it wouldn't electrocute me or
destroy my saw. :-)

Again - we are talking convenience brake - not emergency stop

Yep.

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On Fri, 15 Oct 2010 09:49:34 -0400, "J. Clarke"
wrote:

ABS is intended to save your ass when there's poor traction by
preventing lock--it will also prevent lock on good surfaces but
generally isn't needed for that purpose.

Especially important in the first commercial application of ABS.

Mark

In article , says...

I believe there would be a definite danger factor difference parameter in
that one.

Usually convenient though.

If you consider shoving a pushstick into the side of a saw blade to be
dangerous you should never, ever have sex.




"J. Clarke" wrote in message
in.local...

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

In article ,
says...

On Fri, 15 Oct 2010 09:32:43 -0400, "J. Clarke"
wrote:

In article ,
says...

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.

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

Which is why using the DPDT switch makes it foolproof. and simple
circuitry can handle the injection current timing.

So where can I buy a DPDT switch with a big red "off" button that I can
hit with my knee?

In article , says...

The name "anti-lock" is a misnomer as the brakes successively lock and
release each pulse. On each release steering control is regained. Braking
distance is not improved as admitted in later research.

We all know how it works, and what "later research" is this that shows
that braking distance is not improved on slippery surfaces?

Every test I've seen has shown that an _expert_ driver having made a few
practice stops on the specific surface on the specific day in the
specific vehicle can beat it by a very small margin on _dry_ surfaces,
but not without practice and not on wet, icy, or other kinds of reduced-
traction surfaces.

ABS does not engage until the driver has already screwed up.

"J. Clarke" wrote in message
in.local...
They're not "designed to lock up", they're designed as a compromise
between maximum braking force, fade, pad wear, weight, and cost. Most
disk brakes can be locked.

ABS is intended to save your ass when there's poor traction by
preventing lock--it will also prevent lock on good surfaces but
generally isn't needed for that purpose.

In article ,
says...

On Fri, 15 Oct 2010 09:49:34 -0400, "J. Clarke"
wrote:

In article , says...

Disc brake were around for a lot longer than the ABS systems were ever
implemented.
Disc brakes were not sdesigned to "lock up" but rather be more linear than
shoe brake systems, and fade less.

"Mike Marlow" wrote in message
...
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.

They're not "designed to lock up", they're designed as a compromise
between maximum braking force, fade, pad wear, weight, and cost. Most
disk brakes can be locked.

ABS is intended to save your ass when there's poor traction by
preventing lock--it will also prevent lock on good surfaces but
generally isn't needed for that purpose.

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.


I've had more "success" locking drum brakes on dry pavement than
disks. For CAFE reasons they put the lightest disk brake assembly they
can get away with on most vehicles.

I don't see locking brakes as "success" but I can if I want to lock up
my Grand Cherokee on a dry road.

And we were talking about a caliper from a '76 Lincoln, which has
absolutely _nothing_ "light" on it.

In article , says...

Me think we will wait until somebody shows a design drawing of where the
caliper goes when the saw blade tips at a 45 degree cut.

The same place the Sawstop mechanism goes.

I don't see this working well for a retrofit on a tablesaw with a
tilt...maybe a production lumber yeard saw. For a new design a custom moter
with a caliper brake would be feasible but eliminates a stock motor design
and the price would reach the SawStop price.

IMHO The dynamic brake would be more effective and less maintenance. I am
with clare on that one but then I am a "circuitry" guy.

If you're just looking for a convenience brake either buy a European saw
or use the damned pushstick.

"Mike Marlow" wrote in message
...
Too complex? On the contrary, it's very simple.

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.

You are going out of your way to make this appear to be complicated now.
Both sides? Why both sides? For the discussion at hand, one side would be
ample.


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.


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.

In article ,
says...

On Fri, 15 Oct 2010 13:23:47 -0400, "Mike Marlow"
wrote:

wrote:
On Thu, 14 Oct 2010 22:18:51 -0400, "Mike Marlow"
wrote:

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.
The outer frame of the caliper can be corroded all to heck - no
problem. If the slider mechanism is corroded (which it often is)
braking is less linear, and less predictable. They can (and do) drag.
They can also apply late.

If the piston gets corroded, all the same, but a lot worse.

You are thinking of car brakes and not of calipers in general. That said -
every piece of metal on a car caliper assembly corrodes, yet they continue
to work until the corrosion on the slide becomes excessive. Not something a
table saw would likely see. I agree that with a corroded slider, braking is
less linear, but again, a table saw would not even require a slider, so the
direct comparison to a car caliper need not be made. Calipers exist outside
of the world of automobiles and calipers could make a perfectly acceptable
solution (one of many options) for a table saw. No one has suggested a car
caliper for a table saw, but instead has compared a comparatively hostile
environment where one type of caliper has proven itself.
By definition a "caliper" squeeses - so by definition it requires
some sort of equalization between the forces from side to side of the
"rotor" which means either a slider or a dual piston type caliper.

And the "lincoln" caloper was the first suggestion of a caliper for
saw stopping in this thread.

Asperger's much?

In article , says...

Sorry you asre twisting words and playing with semantics.

Brake lock-up is not when the wheel stops turning. It is when the brakes
will not let go and cease to act linearly.

ABS was not created for brake lock-up. ABS would not help this problem.

Brake lockup _is_ when the wheel stops turning. What you are describing
is brakes broken.



"Mike Marlow" wrote in message
...
You are correct that disk brakes have been around a lot longer than ABS has,
but if you believe that disk brakes will not lock up then you simply need to
drive a car that pre-dates ABS. Disk brakes will most certainly lock up.
Why do you think ABS exists?


Josepi wrote:

Disc brake were around for a lot longer than the ABS systems were ever
implemented.
Disc brakes were not sdesigned to "lock up" but rather be more linear
than shoe brake systems, and fade less.

In article ,
says...

On Fri, 15 Oct 2010 12:54:44 -0400, "Mike Marlow"
wrote:

Josepi wrote:

Disc brake were around for a lot longer than the ABS systems were ever
implemented.
Disc brakes were not sdesigned to "lock up" but rather be more linear
than shoe brake systems, and fade less.


You are correct that disk brakes have been around a lot longer than ABS has,
but if you believe that disk brakes will not lock up then you simply need to
drive a car that pre-dates ABS. Disk brakes will most certainly lock up.
Why do you think ABS exists?
Because most drivers don't (according to our governments and highway
safety people) have the brains to release their brakes when the wheels
start to slide.

The best driver in the world can't sense lock and modulate the pedal as
quickly or consistently as a computer with a sensor on each wheel.

On Oct 15, 6:50*pm, Stuart wrote:
In article ,
* wrote:

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

OK, here goes:

Pair of AC solenoids, one each side of the blade holding a brake pad away
from the blade, paralleled with feed to motor. When motor is powered
brakes are off, when motor switched off solenoids de-energise and springs
press pads against sides of blade. This is a "convenience" brake, no need
for great forces to be applied. Solenoids mounted on a sliding
arrangement, operated by a lever, which allows them to be moved out of the
way for blade changing.

See? I knew there was a rational suggestion around. Now put some
pincer articulated bicycle brake pads at the bottom of the blade and
presto! same results.
Now the aggressiveness of the relief cuts in the blade bodies could
make the pads wear out rather quickly.

On 10/15/10 6:07 PM, Stuart wrote:
In ,
wrote:

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.)

Oak (and a few other woods) contains tannic acid which /over time/ will
corrode ordinary steel screws. I was taught to assemble stuff made with
oak with steel screws and then replace with brass. Choice of materials or
protective coatings will nullify any problems in this instance.


I knew *he* would, but I didn't think anyone else would jump in.
Have you read the thread up until this point, or even a couple posts
preceding?

Context is a wonderful thing.


--

-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 10/15/10 6:29 PM, Robatoy wrote:
Now the aggressiveness of the relief cuts in the blade bodies could
make the pads wear out rather quickly.

Not as fast as that fu@&!ng oak dust!


--

-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 Fri, 15 Oct 2010 17:55:13 -0400, "J. Clarke"
wrote:

In article , says...

The name "anti-lock" is a misnomer as the brakes successively lock and
release each pulse. On each release steering control is regained. Braking
distance is not improved as admitted in later research.

We all know how it works, and what "later research" is this that shows
that braking distance is not improved on slippery surfaces?

Every test I've seen has shown that an _expert_ driver having made a few
practice stops on the specific surface on the specific day in the
specific vehicle can beat it by a very small margin on _dry_ surfaces,
but not without practice and not on wet, icy, or other kinds of reduced-
traction surfaces.

ABS does not engage until the driver has already screwed up.

"J. Clarke" wrote in message
in.local...
They're not "designed to lock up", they're designed as a compromise
between maximum braking force, fade, pad wear, weight, and cost. Most
disk brakes can be locked.

ABS is intended to save your ass when there's poor traction by
preventing lock--it will also prevent lock on good surfaces but
generally isn't needed for that purpose.

Depends what conditions you drive in.
With wide tires in wet sloppy slush, a car with ABS will just continue
going straight. Without ABS I can stop it every time - mabee sideways
part of the way, but at least partially in control. Say within 60
feet, while with ABS I'm still merrily sliding /rolling along with all
4 circuits of the ABS clacking away 150 feet down the road.

Being able to actually lock the wheels to scrub down through the crap
to pavement is almost a necessity under those conditions.

No ABS on my PT cruiser and it's broken on the Mystique - and will
stay that way.

On Fri, 15 Oct 2010 17:56:53 -0400, "J. Clarke"
wrote:

In article ,
says...

On Fri, 15 Oct 2010 09:49:34 -0400, "J. Clarke"
wrote:

In article , says...

Disc brake were around for a lot longer than the ABS systems were ever
implemented.
Disc brakes were not sdesigned to "lock up" but rather be more linear than
shoe brake systems, and fade less.

"Mike Marlow" wrote in message
...
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.

They're not "designed to lock up", they're designed as a compromise
between maximum braking force, fade, pad wear, weight, and cost. Most
disk brakes can be locked.

ABS is intended to save your ass when there's poor traction by
preventing lock--it will also prevent lock on good surfaces but
generally isn't needed for that purpose.

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.


I've had more "success" locking drum brakes on dry pavement than
disks. For CAFE reasons they put the lightest disk brake assembly they
can get away with on most vehicles.

I don't see locking brakes as "success" but I can if I want to lock up
my Grand Cherokee on a dry road.

And we were talking about a caliper from a '76 Lincoln, which has
absolutely _nothing_ "light" on it.


Well, the Ford Aerostar with factory pads could never slide the front
wheels on dry pavement - and it only had rear ABS. When I put carbon
metallic "taxi duty" pads on it I could finally get enough braking
action to lock the wheels whenever I wanted to.

I kinda missed the 1976 part - yes, it was still pretty heavy - but
not as heavy as pre-1970

On Fri, 15 Oct 2010 18:04:15 -0400, "J. Clarke"
wrote:

In article ,
says...

On Fri, 15 Oct 2010 12:54:44 -0400, "Mike Marlow"
wrote:

Josepi wrote:

Disc brake were around for a lot longer than the ABS systems were ever
implemented.
Disc brakes were not sdesigned to "lock up" but rather be more linear
than shoe brake systems, and fade less.


You are correct that disk brakes have been around a lot longer than ABS has,
but if you believe that disk brakes will not lock up then you simply need to
drive a car that pre-dates ABS. Disk brakes will most certainly lock up.
Why do you think ABS exists?
Because most drivers don't (according to our governments and highway
safety people) have the brains to release their brakes when the wheels
start to slide.

The best driver in the world can't sense lock and modulate the pedal as
quickly or consistently as a computer with a sensor on each wheel.
Which does not NECESSARILY translate into shorter stopping distances
under all (low traction) conditions

On Fri, 15 Oct 2010 17:52:33 -0400, "J. Clarke"
wrote:

In article ,
says...

On Fri, 15 Oct 2010 09:32:43 -0400, "J. Clarke"
wrote:

In article ,
says...

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.

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

Which is why using the DPDT switch makes it foolproof. and simple
circuitry can handle the injection current timing.

So where can I buy a DPDT switch with a big red "off" button that I can
hit with my knee?

If you have an OFF button it is contactor controlled - you simply
change the contactor.

On Fri, 15 Oct 2010 16:34:51 -0500, Steve Turner
wrote:

On 10/15/2010 1:16 PM, wrote:
OK - the whole premise of using a caliper, regardless of the source
of the caliper, for a retrofit to an existing saw has all the
drawbacks I have stated. OK, the corrosion might be a bit overstated -
but it IS an issue that would have to be dealt with -nas it has to be
dealt with in automotive, bicycle, and motorcycle applications. Using
a caliper of any sort on the blade, even on a purpose built clean
sheet saw design has engineering problems that would be best avoided
due to complexity (like blade changing, adjustment for dado use, etc.)
Putting the caliper (or drum) on the opposite end of the arbour
handles most of those issues, but again, on a clean sheet design. As a
retrofit it is still problematic.

That's a blanket statement. I would say that depends on the saw.

Putting the brake on the motor is
the simplest solution - wheather mechanical or electrical, and
wheather direct drive or belt drive.

That's what I concluded after inspecting my saw (the Unisaw). Other saws may
be different.

Either way, electrical application is the simplest, cheapest
alternative (compared to hydraulic, mechanical, pneumatic, or
percussive application) - and if you are going to use electical or
electronic controls anyway, why not use electrical braking all the
way?

In my case, it's because I can understand and implement mechanical devices;
electrical, not so much. If somebody were to implement and test and guarantee
an electrical braking system that could be retrofitted to my Unisaw I would
certainly be interested.

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

I don't recall rejecting yours, I only recall you rejecting mine... In any
case, for the Unisaw I think it would be relatively simple to actuate the brake
with a mechanical lever that's mounted in front of the power-off switch.
Initial pressure on the lever would actuate the power-off switch and cut power
to the motor, additional pressure would actuate the brake. This is exactly the
way the mechanical (automotive style drum) brake on my MiniMax bandsaw works.
And work it does; like a dream, and I can tell you that those upper and lower
drive wheels are about 20lbs apiece and have WAY (*WAY*!) more mass and
centrifugal force than a free-spinning table saw blade assembly.

It is the only virtually universally implementable retrofit or add-on
solution that does not require custom engineering for every saw it
might possibly be applicable to.

A lot of dreamers on the wreck - but how many implementers?

I have every confidence that I can implement a mechanical solution on my
Unisaw, and believe me, the naysayer attitude of a certain few (ahem) has just
about ticked me off enough to follow through with it. My only problem is
carving out the time to get it done; I have precious little of that these days.

So what's stopping YOU from being an implementer?

Absulutely nothing.
If I feel I need or want something, or some feature on something I
already have, I figure out how to do it and do it.
I decided I wanted an electric car - I built it.
When I was a kid I wanted a stereo record player - I built it.
I decided 10 years ago I wanted to fly - so I'm building an airplane -
and not from a kit - from plans.
I saw a "rhodes car" and figured I could build it better and lighter
for a lot less, so I built it.
Same with a tandem bike.

Also, if electrical convenience braking is such a bad idea, why is it
virtually the ONLY method used on commercially available table saws,
particularly in the "consumer grade", "contractor", or "semi-pro"
lines?

You never heard from *me* that it was a bad idea.

Virtually every hand held circular saw on the market today has a
"dynamic blade brake" as a standard feature as well.
So does virtually every quality cut-off or miter saw.

My 3HP Makita plunge router has one and I love it. So does my Delta chop saw,
but that thing's a piece of crap in most every other respect, so I avoid using
it unless I have to.

Best of all, it COULD be made as a simple plug-in module that you plug
the saw into - replacing the existing power switch, on all but the
higher end saws that use contactors instead of a simple switch.

It could be made offshore, in reasonable quantities, to sell for less
than $50 retail.
It could be implemented, from scratch, by a reasonably competent
tinkerer for under $100 buying all the parts new from local or online
sources, and could be installed on ANY saw. Either as a plug in as
above, or wired directly into the saw. Contacter controlled mabee add
another $50.

I would have zero confidence in doing that unless I was working from plans
offered by another "tinkerer" who had already succeeded and was able to
demonstrate that it worked and was safe and that it wouldn't electrocute me or
destroy my saw. :-)

Again - we are talking convenience brake - not emergency stop

Yep.

On Fri, 15 Oct 2010 23:50:50 +0100, Stuart
wrote:

In article ,
wrote:

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

OK, here goes:

Pair of AC solenoids, one each side of the blade holding a brake pad away
from the blade, paralleled with feed to motor. When motor is powered
brakes are off, when motor switched off solenoids de-energise and springs
press pads against sides of blade. This is a "convenience" brake, no need
for great forces to be applied. Solenoids mounted on a sliding
arrangement, operated by a lever, which allows them to be moved out of the
way for blade changing.
That would work - assuming there is space to mount it and the
associated bracketry. Mechanically still more complex and therefore
prone to failure.

Generally speaking, an electronic implementation/solution is at least
twice as reliable as a mechanical solution, and the difference
increases as the mechanical complexity increases. More moving parts
means more to fail.

Geeeeee. Ask a mechanic about brakes. What a concept...LOL


wrote in message
...
And there is NO contadiction to my statement. On first application, a
drum brake will ALWAYS outperform a disk on first application. Many
times also on second application. Disk brakes only outstop drum brakes
when both are hot.
Disk brakes are not "designed to lock up" They are designed that you
CAN (in many, but not all cases) lock the wheels on clean dry pavement
with hard brake application. You CAN lock the brakes in poor traction
conditions, but the locking capability is only due to their stopping
power being excessive foe some conditions. They are, by design, LESS
likely to lock than a Bendix type self energizing drum brake.

If you consider pushing an oak stick into the side of a carbide toothed
blade turning at 4500 PM as safe as pressing a pushbutton on the side of the
table saw you should never have children.


"J. Clarke" wrote in message
in.local...
If you consider shoving a pushstick into the side of a saw blade to be
dangerous you should never, ever have sex.


In article , says...

I believe there would be a definite danger factor difference parameter in
that one.

Usually convenient though.





"J. Clarke" wrote in message
in.local...

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

I haven't seen the SawStop demonstrated with a 45 degree tilt cut. Can it
actually tilt? Has anybody actually seen the mechanism under the table?

What happens when the sensitive moisture sensor is full of titanic acid oak
sawdust?



"J. Clarke" wrote in message
in.local...
The same place the Sawstop mechanism goes.


In article , says...

Me think we will wait until somebody shows a design drawing of where the
caliper goes when the saw blade tips at a 45 degree cut.

OK, so we go with a caliper brake of some kind...Looks simple enough on the
surface.

What would operate it? Would it be electrically controlled? Automatic,
Handjob (manual)?

It would have to mounted to the mechanism that tilts the blade so it goes
with it.



"Steve Turner" wrote in message
...
In my case, it's because I can understand and implement mechanical devices;
electrical, not so much. If somebody were to implement and test and
guarantee
an electrical braking system that could be retrofitted to my Unisaw I would
certainly be interested.

I have every confidence that I can implement a mechanical solution on my
Unisaw, and believe me, the naysayer attitude of a certain few (ahem) has
just
about ticked me off enough to follow through with it. My only problem is
carving out the time to get it done; I have precious little of that these
days.

ADHD acting up again, hopper?
Reading comprehension skills a little off?


"Steve Turner" wrote in message
...
Only a top-posting moron like you would claim that Outlook Express is a
superior news reader. YOU and your stupid news reader are always taking a
perfectly good forward-reading conversation and turning it completely
backwards, and when YOUR actions cause somebody else to misinterpret the
flow
and content of the conversation (what a surprise) YOU blame it on THEIR
newsreader.

No big deal. Text mediums get messy after a while.

Yeah, because of idiots like you.

--
Free bad advice available here.
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/

On 10/15/10 8:54 PM, Josepi wrote:
If you consider pushing an oak stick into the side of a carbide toothed
blade turning at 4500 PM as safe as pressing a pushbutton on the side of the
table saw you should never have children.


Here it is on video. I should have my testicles revoked.

http://www.youtube.com/watch?v=XqFBPAXcX5U


--

-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 10/15/10 8:57 PM, Josepi wrote:
I haven't seen the SawStop demonstrated with a 45 degree tilt cut. Can it
actually tilt? Has anybody actually seen the mechanism under the table?

What happens when the sensitive moisture sensor is full of titanic acid oak
sawdust?


Are you joking, now? Please tell me you are. (hint: I'm giving you an
out, here.)


--

-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 ,
says...

On Fri, 15 Oct 2010 17:52:33 -0400, "J. Clarke"
wrote:

In article ,
says...

On Fri, 15 Oct 2010 09:32:43 -0400, "J. Clarke"
wrote:

In article ,
says...

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.

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

Which is why using the DPDT switch makes it foolproof. and simple
circuitry can handle the injection current timing.

So where can I buy a DPDT switch with a big red "off" button that I can
hit with my knee?

If you have an OFF button it is contactor controlled - you simply
change the contactor.

So where is the "contactor" on my Ridgid table saw and my Craftman band
saw, and why is there no "OFF" button on my contactor-controlled dust
collector?

In article ,
says...

On Fri, 15 Oct 2010 23:50:50 +0100, Stuart
wrote:

In article ,
wrote:

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

OK, here goes:

Pair of AC solenoids, one each side of the blade holding a brake pad away
from the blade, paralleled with feed to motor. When motor is powered
brakes are off, when motor switched off solenoids de-energise and springs
press pads against sides of blade. This is a "convenience" brake, no need
for great forces to be applied. Solenoids mounted on a sliding
arrangement, operated by a lever, which allows them to be moved out of the
way for blade changing.
That would work - assuming there is space to mount it and the
associated bracketry. Mechanically still more complex and therefore
prone to failure.

Generally speaking, an electronic implementation/solution is at least
twice as reliable as a mechanical solution, and the difference
increases as the mechanical complexity increases. More moving parts
means more to fail.

And that is why all cars have electronic brakes . . .

In article , says...

If you consider pushing an oak stick into the side of a carbide toothed
blade turning at 4500 PM as safe as pressing a pushbutton on the side of the
table saw you should never have children.

Sex is more dangerous, especially if you're a woman.

"J. Clarke" wrote in message
in.local...
If you consider shoving a pushstick into the side of a saw blade to be
dangerous you should never, ever have sex.


In article , says...

I believe there would be a definite danger factor difference parameter in
that one.

Usually convenient though.





"J. Clarke" wrote in message
in.local...

But if I have to push a button to stop the blade I may as well just
shove a pushstick into the side of it.

In article , says...

I haven't seen the SawStop demonstrated with a 45 degree tilt cut. Can it
actually tilt? Has anybody actually seen the mechanism under the table?

So you're saying that people are paying 3400 bucks for a saw on which
the big wheel on the side that is supposed to adjust blade tilt doesn't
do anything? And none of the reviewers have noticed?

What happens when the sensitive moisture sensor is full of titanic acid oak
sawdust?

Whatever gave you the idea that there's a "sensitive moisture sensor"?





"J. Clarke" wrote in message
in.local...
The same place the Sawstop mechanism goes.


In article , says...

Me think we will wait until somebody shows a design drawing of where the
caliper goes when the saw blade tips at a 45 degree cut.

On Oct 15, 10:27*pm, -MIKE- wrote:
On 10/15/10 8:54 PM, Josepi wrote:

If you consider pushing an oak stick into the side of a carbide toothed
blade turning at 4500 PM as safe as pressing a pushbutton on the side of the
table saw you should never have children.

Here it is on video. *I should have my testicles revoked.

http://www.youtube.com/watch?v=XqFBPAXcX5U

--

* -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

You can SEE the rust forming....

A pushbutton would still be safer than the possibility of oak rust flying
into your eyes.


"Robatoy" wrote in message
...

You can SEE the rust forming....

So you are saying the SawStop is useless and everybody knows it?
Perhaps you can explain where the "titanic acid" would come from.


"J. Clarke" wrote in message
in.local...

So you're saying that people are paying 3400 bucks for a saw on which
the big wheel on the side that is supposed to adjust blade tilt doesn't
do anything? And none of the reviewers have noticed?
Whatever gave you the idea that there's a "sensitive moisture sensor"?


In article , says...

I haven't seen the SawStop demonstrated with a 45 degree tilt cut. Can it
actually tilt? Has anybody actually seen the mechanism under the table?
What happens when the sensitive moisture sensor is full of titanic acid
oak
sawdust?

They do. How many cars have you seen that have cables running to the rear
brake lights?


"J. Clarke" wrote in message
in.local...
And that is why all cars have electronic brakes . . .

In article ,
wrote:
...snipped...
Generally speaking, an electronic implementation/solution is at least
twice as reliable as a mechanical solution, and the difference
increases as the mechanical complexity increases. More moving parts
means more to fail.

Then why don't we have automotive brakes that work that way?


--
When the game is over, the pawn and the king are returned to the same box.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar.org

On 10/15/10 10:23 PM, Josepi wrote:
A pushbutton would still be safer than the possibility of oak rust flying
into your eyes.


I know that an electronic or mechanical technically be "safer," not to
mention more convenient. No one ever argued that it's a better
alternative. I only brought it up to show how easily a blade can be
stopped with very little pressure to one side of the blade.

I just thought it was laughable that you think it's somehow dangerous.


--

-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 10/15/10 10:33 PM, Josepi wrote:
So you are saying the SawStop is useless and everybody knows it?


Holy cow, I hope you're just messing with us.
Please, for your sake, I hope you're just trying get us riled up.


--

-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 10/15/10 10:34 PM, Josepi wrote:
They do. How many cars have you seen that have cables running to the rear
brake lights?


What grade are you in?


--

-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 Fri, 15 Oct 2010 22:29:01 -0400, "J. Clarke"
wrote:



If you have an OFF button it is contactor controlled - you simply
change the contactor.

So where is the "contactor" on my Ridgid table saw and my Craftman band
saw, and why is there no "OFF" button on my contactor-controlled dust
collector?



If you have a "start" and a "stop" button, generally there is a
contactor OR a solid state relay somewhere on the unit.
There are exceptions - mechanical switch controlled by 2 mechanical
linkages instead of a toggle switch
A contactor can be latching, or not latching. Latching contactors use
a start and stop putton. Non latching contactors are just relays that
take the load off the switch. Your dust collector is likely the
latter.
You can tell if you have a latching contactor by unplugging the saw
with it turned on. If it restarts when you plug it back in it's not a
latching contactor.