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Steve Turner[_3_]

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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