Armature Brake for Band Saw

Not really what you are looking for, but I thought this was interesting:

A table saw that won't cut your skin

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

Hello Guest,

Further down the page is a similar thing but on a bandsaw. Very clever kit!

http://www.youtube.com/watch?v=4TeCaxWA_iM&NR=1

Hello Guest,

Further down the page is a similar thing on a bandsaw. Clever bit of kit!

http://www.youtube.com/watch?v=4TeCaxWA_iM&NR=1

Maybe that is why it is a bad saw.

However, my new 17 inch bad saw has no brake whatsoever

Show it a piece of scrap wood!

If you are up for doing some design work, I can recommend a couple of companies that might be able to supply a brake that might be adapted to fit.

Kobelt

Eaton Airflex

That is correct. It is called dynamic braking. Shorting the stator (field) leads of an AC induction motor will reduce coasting time. Residual magnetism in the motor allows the rotating armature to induce an electric current in the stator winding, which in turn serves to increase the magnetic field, slowing the rotational speed.

http://www.claytonengineering.com/Training/myweb6/Module16/Output/BrakingMotor.html

Coasting time can be much more severely reduced by passing a small DC current through the stator winding. For fractional horsepower induction motors, a small DC power supply and a change-over switch will do the job. For larger induction motors, a variable frequency drive used for speed control may also have provision for magnetic braking.

I am uncomfortable applying a DC source to the motor, however he idea of shorting the neutral and supply lead with a switch appears fairly simple.

What I like even more is Bubbapedi's idea of using a Phase Inverter.

I have several PI's in my shop that convert 220 VAC Single Phase to 220 VAC Three Phase and I like them very much. They not only allow me to run 3 phase equipment but they have soft start, soft stop to prevent inertial issues but they offer torque compensation as well at slow speeds.

It did not occur to me to investigate these devices as a way of stopping the band saw safely. If it will do that, not only will I have addressed a potential hazard but I may also have come up with a method for infinitely varying the blade speed of the saw, which is now limited to two speeds.

The current set up requires stopping the machine and a time consuming change of pulleys.

With a 3 phase inverter, not only might I stop the blade quickly, but I can regulate and perhaps over-speed the motor like I sometimes do with my three phase driven devices (vertical mill, machine lathe, jointer).

I'll check out the inverter immediately. I'll even look into swapping out the current single phase motor for a three phase.

This has been a very beneficial string.

Thanks to all who offered solutions!

L.J.

What you said will only work on a PMDC motor (permanent magnet), but will take too much time for an AC induction motor, in this case you have to inject DC current thru the stator windings using a large contactor that conects an SCR rectifier for an adjustable time right after the supply lines to the motor are disconnected.

***NOTE** Won't work during power failures.

Simple answer:-

You are completely wrong, it works on practically all normal AC & DC motors.......even ones without permanent magnets...(Maybe not synchronous......)

By the way, very few AC motors have permanent magnets. In my personal experience, NONE!!

You may not even know or understand that it is also possible to take a running 3 phase AC motor and drive it with say a petrol engine and produce 3 phase electricity from it....complicated but it can be done!!!

This is why dynamic braking works also on 3 phase squirrel cage induction motors to bring them to an abrupt halt!!

We have already had about a year ago a blog on this subject......

I searched around and found this previous blog that mentions this phenomina quite clearly.

http://cr4.globalspec.com/comment/122389

The only negative side when using such a method is that although it will quickly bring a motor to an "almost" stop, the motor is not "held" in that position and sometimes the motor revolves for a further single revoltion, before fully stopping.....

So it is great for power tools of any sort in a workshop, but not good enough for a Crane motor for example, which needs a mechanical brake to remain still inspite of a heavy mechanical load.....

But it would severely reduce the maximum possiböe speed of the crane's load, even if the mechanical brake ceased to function.....

If anyone has a small to medium induction motor to hand, wrap a cord about the shaft and make like starting a mower motor. Count how many revolutions it manages once the cord is off.

Short all 3 phases together, try it again, it will not turn as fast and will stop immediately the cord runs out.....

This is a very convincing test.....

This is especially obvious with good stepper motors. On a free (not connected to anything) motor, make sure all leads are separated, and feel the torque required to rotate the shaft. You will feel the individual poles. Connect all leads together (short all windings), and rotate the shaft. The additional effort required is quite notable!

Good post...

Main AC generators have a small DC exciter on the same shaft that generates a DC voltage for the Rotor in the main AC generator.

There is always enough residual magnetism in the pole pieces to start the DC generator voltage and once a small voltage is made, the pole pieces are strengthened in their magnetism by field coils on them, supplied by the initial voltage generated via the residual magnetism....

There is never any need to replace the pole pieces, they just need "flashing" before the generator is run up for the first time.....no more, no less......

If there was a major "accident" there might be a need to re-flash the field coils again, or if it was not used for a long time and the residual magnetism got so low, it was not "self starting" anymore. Thought I personally have never seen either scenario......they always self started as the flashing had been first carried out by the manufacturer......

Just who the heck do you think you are? Just showing up under the guise of guest and an slamming one of our more experienced regulars.

Andy has definately been there and done that. He probably posessed more experience than yourself, before you were even hatched.

I have been listening to what he has to say for a while now and I have really come to respect his opinion.

"FYI: generators ALWAYS use permanent magnets that you should renew or replace every certain time"

WHAT? you really sound foolish with an eronious statement like that. Where are your references?

Take your own advice

"I don't need you to tell me "you were right" it's enough for me that you find the truth."

Do some research yourself before making an incorrect assertion such as that.

http://en.wikipedia.org/wiki/Electrical_generator

http://www.sdrm.org/roster/diesel/diesel_fund.html

http://www.ee.adfa.edu.au/staff/valu/TEACHING/Machines/lab2.pdf

Rant over

Hello IanR,

Take control of yourself and let the condescending, 'guest', find his own way.

If a member,and he cannot be bothered to entire his user name, or perhaps he thinks he can say anything including effectively calling names, (pathetic), well his rudeness and any others rudeness while entering as guest or a member, will be noticed by admin and he could be asked to leave (to put it in a nice way). Or give him enough rope and do not answer him again or anyone like him with that 'ATTITUDE', AND HE WILL HANG HIMSELF!

This is a professional forum and not a place where 'street talk rules'! He will find that out soon enough.

Maybe he started with a bad day or other troubles...................well, that should not be brought onto the site unless he explains what is wrong and perhaps apologizes and explains why he may be in a bad/rude mood.

With ref' to your post getting two off topic votes for being off topic. I did not vote it off topic. Strictly speaking most of what you said was off topic. But you also included helpful links which were not off topic! And though it could be said that you could have published it as off topic, the stuff you had to say and the links may not have been seen by most, so publishing in the normal open forum which is 'on topic' is the correct thing to do under the circumstances.

I hope this bully can mend his words and swallow his pride and join! It is a great site with some really clever people who are here mostly to help others. The sooner he gets that message the quicker he will or should at any rate, change his attitude and the way he talks to others. After all, any reply he makes is likely to be to a seriously well qualified and experience Engineer! If he is one, then would he like it if one of us spoke in such a manner, I do not think so?

I know this is off topic so am ready for the avalanche of off topic votes, but I think it right to publish this in the normal forum.

Thanks for your understanding.

I (and someone else) have each taken one off your own off topic score as it was actually on topic I feel.....

If what he said about what he has been involved in is really true, it really is no surprise to hear of "professionals" really screwing up. You read it in newspapers etc,,

.......which is one of the reasons why I try and do everything myself at home as I simply do not trust "Professionals" much.....

The really sad point is that he still believes he is right.......nothing will ever change his mind.....

I'll attest to Andy Germany's statement that it: " is also possible to take a running 3 phase AC motor and drive it with say a petrol engine and produce 3 phase electricity from it...."

I remember being in a number of machine shops that did not have 3 phase electricity so they generated it themselves just as Andy described. They spun an unloaded 3 phase motor with a belt drive off a 220volt single phase motor and picked off the 3 phase from the driven motor.

I don't know how they wired it but they told me it was simple. Judging from what I saw, I believe them and Andy. The last time I checked, such units were still commercially available.

Given the availability of high capacity, solid state inverters (I have a solid state Mitsubishi unit as well) such a method is probably not as efficient but they still work.

L.J.

Of course, you'll need also a timer.

I had in mind a Hydraulic Disk Brake, and though it is not ideal, as it would not be automatic, it would work if there was a power failure when, in the unlikelihood of an accident happening just as a power outage took place?

What you need for such an application is a spring applied, hydraulically (or pneumatically or electrically) withdrawn brake. In that way when power is lost, the brake slams closed by spring pressure.

Hello Rorschach,

Thanks for the reply post!

Like an electromagnet then, with the power perhaps supplied by a battery?

If it is a magnetically withdrawn brake, you'd expect it to be supplied from the power line just as the motor is. A battery would not last long since it has to generate a fairly high current to counteract the strong springs that are biased to close the brake. I've used the two cylinder pneumatic one on an offshore umbilical winch. whenever the air motor that turned the winch was powered up, the brake was released from the same air supply. when the motor was deenergized, the pressure was vented slamming the brake shoes home. That was probably the part of the winch that worked best. The air motor required (it was a Gardner Denver 11 hp radial air motor but we only generated 6.5 HP out of it.) to generate the torques and speeds needed took far more CFM of air than the customer could deliver. And a two speed gearbox would have cost an arm and a leg and taken far longer than we had to work within to get. so we ended up muddling. we decided that the torque was the prime importance and sized the sprockets accordingly and the speed was whatever we could get out of it.

Hello Rorschach,

Thanks for getting back to me.

I see what you mean with the battery not lasting long. And think your air motor is a good idea under some types of use.

Whatever is used it has to be small or it would get in the way of the usual use for the saw?

There is a way (I personally do not see a need for it in this example as all that is needed is to stop the saw parts turning, there is to my mind no need to hold them still at the end, or have I missed something important?) to use magnets and electricity for braking with power loss.

You use a strong permanent magnet to close your mechanical brake against a light spring. There is also a coil around the magnet, that is wound to oppose the magnetism, nulling it out in fact. Loss of power, means also loss of power to the coil, this means that the nulling effect is lost and the magnet brakes the moving parts and holds them still.

This would be of more use in a crane or winch system where a heavy load may be still attached in some way to the motor when power is inadvertently lost....

In Germany, in office buildings, fire doors are held open by a magnet. If the fire alarm is set off, a pulse of electricity through the coil allows the magnet to lose its power for a short time and the door spring closes the door.....not permanently of course, but it provides a way of containing fires in one part of a building, but still allowing people to escape....

Hello Andy,

Just to say a very interesting post by you on post 57!

For this application holding power requirement is nil, but it comes as part of the package and hurts nothing. For the winch application, yes we had to keep up to 7000+ ft of subsea umbilical from trying to spool off the winch if air power were lost or the drive chain broke. The way most of these brakes work you have a pneumatic or hydraulic cylinder that pulls against the springs. What you describe would probably work, but I am unaware of an off-the-shelf design that works in that manner.

As I mentioned, it was not intended in this application.....it was just describing a possible method of holding a winch still after losing power.....

Hello Andy,

I think what you suggest would work OK. As would some of what rorschach said. Both posts mention auto' mechanisms which are better than what I could think of, which needed the input of someone to operate the brake, not something you would think to do if half your body is being 'eaten' 'at a rate of knots!'

bb

Wouldn't it be easier to have a switch that when power is supplied to the motor it would release a friction brake on the main wheel and when power is removed it would engage the brake.

Hello Andy,

I tried this on a test rig with just a spindle and three phase power to a small motor.

I wanted to stop the machine 'end' and catch belts simultaneously. And it worked.

It was an idea I had in my mind but not being an expert in 3 phase power, I used an isolated set up on a betch to try it and it was very successful.

I did not want to screw the machine which is why I tested first.

It would not take much setting up to use a set of car disk-brakes and pads if you wanted to stop it more or less instantly?

Provided the saw is wide enough?

Just a thought.

Well done and many thanks for proving the theory for us all.

I haven't done it in years, but I hadn't forgotten it!!

If I understand Any Germany's suggestion of shunting the two wires, then it suggests that converting the existing double pole single phase switch to a double pole double phase switch will allow safe, fool proof automatic shunting when the power to the motor is cut.

Is my interpretation correct Andy?

L.J.

If I understood you correctly, yes......basically you only need to remove power and short the 3 fields of a 3 phase motor together. Nothing more, nothing less.

Although such an action almost stops the motor (in approximately the same time as the motor takes to run up (assuming no reduced current starter). It does leave the motor still making on average a single revolution un braked. It also does not "hold" the motor still afterwards as a mechanical brake does. So it cannot alone be used for say a crane hoist motor, though it will severely restrict the speed of the load descending, but not stop it.....

If the method is still too abrupt (with power tools that is what is normally required), then heavy duty but low value resistors need to be substituted for the short circuit....on a 3 phase motor, one could short say only two field coils together instead of all 3, or even, if the middle connection is available, short circuit just one field coil.

I have to admit that the last two ideas are theoretically good but not actually ever tested by me...... but they should stop the motor in a slower manner, not so abruptly.

Single phase induction motors can also be stopped safely in this manner as can AC or DC motors with brushes......

There are some strange motor types around (synchronous for example) that I have also never tried to stop in this manner.....for synchronous, its probably never required.

The answer is to try it out yourself if there is a need for rapid braking.

The band saw should be dead easy to stop quickly, that is the perfect example of such a need for a simple and effective method to stop a motor quickly..

I would go a step farther and consider a DP3T contactor set up so that a momentary switch latches it closed (and another in series with the coil unlatches it). that way even if power is lost, it shunts the winding.

That's worth considering Rorschach, if for no other reason than the simple fact that if the power goes out while I am sawing, I will suddenly find myself in the dark with a moving cutting blade I can't see.

Your suggestion would drag the blade to a halt, independently of the on-off switch, without my intervention.

Passive safety is worth while.

Thanks

L.J.

Very true, thats a valid point that I had personally not even considered before now.....

Hello LJ,

I agree with your "passive safety" idea, but you could alway get a lamp which stays on charge, and if the power goes it will come on. I have one and need another couple.

http://www.google.com/search?client=safari&rls=en-us&q=automatically+charges+lamp+which+comes+on+when+the+power+fails&ie=UTF-8&oe=UTF-8

yeah but you still have to pull the bloody stump away from the blade and turn the machine off...

Hello Rorschach,

You are a laugh!..............I think I would be to busy dying, or searching through the 'mush' for fingers and stuff they could stitck back on! Does not bear thinking about really.

Take care my friend.

Good idea....and very simple to install.....

I'm just thinking out loud here, but if this were a three phase motor, (which this obviously is not.) you could momentarily reverse two of the phases for a split second before disconnecting the power causing the motor to try to instantaneously reverse, eating the forward momentum before shorting the phases together. But that would probably be pretty hard on the motor.

Ouch. I'm guessing the that the current spike, as well as physical shock, would be phenomenal. Maybe somekind of current limiting aparatus would be in order. But, then again, considering that time may be of the essence, it that could reduce the effectiveness of that method.

Of course, the already suggeste method; shorting the windings, may not be much more of an elegant way (and possibly almost as violent).

Ian wrote: "Of course, the already suggeste method; shorting the windings, may not be much more of an elegant way (and possibly almost as violent)."

On the contrary Ian. As the force field generated slows down the armature, the field strength is simultaneously reduced. The result is a "soft landing" This is, as was pointed out, the underlying principle in the successful use of what is called Dynamic Braking.

L.J.

Ok, I stand corrected.

Thanks for setting me straight.

Ian

Yeah, it'd probably fry the windings, not to mention pop the circuit breaker AND shear the armature from the shaft. But hey, it'd stop on a dime! Once.

Its pretty quick and the motors I have used it on slow down really quick (1.5 seconds?) and just end up turning about one slow final rev before finally stopping.....

Something similar IS done for certain 3 phase motors, but they use DC to do it!!! So you were not so far from the mark!!

my question is, Is 7 seconds all that long to even be worrying about it?

I know I wouldn't, I had an Old Rockwell cast iron beast that would glide for an eternity like a minute or maybe even more after shutting off the power, never thought a second about it?

Just cvurious as to why you want it to stop fast anyway.

Anytime you make something that has a lot of inertia stop fast it is asking for some part to fail also.

Its actually a safety issue. if one is concentrating on the work, its üossible to accidently get the fingers moving before the brain.......

Also, if an accident does happen, 7 seconds is an age to wait with mangled fingers, or clothing caught and dragging you into the machine......!

Hello NSS,

7 seconds when the saw teeth are moving at perhaps 9' ~ (3 meters) a second means it will more than cut you down the middle by the time it stops!

7 x 3 Meters is 21 Meters, ~63' ! Not something to be taken lightly. I am with Andy on this. if it catches your sleeve or coat it will rip the whole garment off before you can blink! ;=). Try and stop yourself using a bandsaw with no protection built in and as one arm is very quickly made into 'mincemeat', the other hand could easily grab the saw to pull the first hand out? May sound silly but you just can't take the chance on that type of machine. Always use a guard.

And assume the most outrageous .......... IE: a child or someone who is 'a Unicycle short of a wheel !'. (See what I mean?);=)

"Is 7 seconds all that long to even be worrying about it?

I rarely go to the saw for just one cut. More often than not several cuts are needed.

Waiting for the blade to halt (it takes ten not seven seconds) not only generates impatience but risks damaging the wood. This condition tends to generate impatience.

Impatience around machine tools is not a good thing!

Without knowing the exact Federal regs, I can say with some certainty that the lack of a brake will fail any OSHA safety inspection in any manufacturing environment in a lot less than seven seconds. And for good reason.

A machine like that can amputate a finger in a few seconds, even when coasting to a stop.

L.J.

Very well put.

Is it even legal to sell such a machine in this "state"????

Andy asked "Is it even legal to sell such a machine in this "state"????"

Yes it is.

Fortuntely, "Big Brother" (Government by another name) has not yet intruded into our private lives to that extent. There are some standards by groups such as Underwriters Laboratories in the US and Canadian Standards Association who place their seal of approval on certain devices (electrical for the most part). This issue is outside their realm of influence.

OSHA (Office of Safety and Health Administration?) only deals with the work place. If an Federal OSAH inspector comes into a factory emloying these machine and does not see the requisite guards on hazzardous equipment, that can result in a fine and a suspension of operations until the ommissions are corrected.

Most manufacturers of machines (like band saws) offer upgrades that incorporate the items needed to satisfy commercial applications. More expensive models of this very same saw do have brakes. I've never had a saw that continued to spin and so I did not recognize the need for one until I took possession of this one.

You've been a very supportive contributor. Thank you.

L.J.

Which begs the question, if the manufacturer offers a brake for this model, would it not be simpler to buy the kit and install it?

"would it not be simpler to buy the kit and install it?"

Why didn't I think of that?!

Thanks

L.J.

I wasn't trying to be sarcastic or anything, but by buying the brake designed by the manufacturer and installing it, you put the liability squarely on the manufacturer (well the manufacturer could claim you installed it wrong I guess...) instead of taking the liability on yourself by trying to design the safety system. Now if this is just for your own use, hey, no blood no foul, but if anyone else ever uses it, including your neighbor or your kid or your wife etc. then you need to think about the liability involved. You might find that your homeowner's ins. won't cover any accidents that arise out of the use of "modified" equipment. If this is for your employer, then things really get complicated.

But there is nothing to say you could not build the contactor and switches into the outlet box and just plug the saw into it. That way you have not actually "modified" the saw itself and have not incurred any liability resulting from it.

I hate lawyers.

Some manufacturers of large (>18") bandsaws, have brakes on their saws. Maybe if you check them for repair parts for their saws, you can find the parts you can adapt to your saw.

BTW the saws that stop and won't cut flesh that another poster mentioned can be found here:

http://www.sawstop.com/howitworks/how_overview.php

Hello Rorschach,

makes you wonder why all saws do not have this built in safety?

I realize there will be saws from 20 years ago which still work fine, but any saw built since the stop quick thing was invented should have them. I suppose it can be thought of like doors on a car or seat belts and wind screen?

bb

Well put!

For example look how long it took to get seatbelts fitted in all cars.......70 years or more......

Hello Andy,

Yes it certainly makes you wonder why these things are not fitted to every saw?

My electric lawnmower shorts out its motor and stops in well under a second when the run lever is released, and so did the previous one, purchased around 15 years ago. Both were DC Permanent magnet motors.

I have several saws; none of them have this feature. As you say, it seems like it should be required, since the only addition is another set of contacts in the power switch.

Actually I believe they are talking about the system used by SawStop which puts a charge on the blade and then looks for a voltage change caused by something conductive touching the blade which then launches a chunk of aluminum at the blade to stop it in under 5ms.

Baby Bear wrote: ". . makes you wonder why all saws do not have this built in safety?"

One of my more inquisitive friends went to the manufacturer of that table saw and discovered that the safety device only works once! AT that point you must return the saw, at your expense, to have components replaced. The cost of doing so is over $100 and of course you must still bear the crating and shipping costs which are considerable.

At least this was the case when that saw first hit the US market and the video was being aired by most everyone.

One doesn't see it anymore and, given my heavy involvement with shop tools, that suggests that it never caught on.

I wouldn't have one

L.J.

Yeah, I remember reading about that system and it seemed like a rather extreme method of stopping the saw.

I wonder how well the so called smart safety system can differentiate between the conductivity of flesh verses, say a really wet piece of wood. Very expensive and troublesome if the system gets false tripped. Then again, if it was your flesh that tripped it, and thus saved by it, I suppose that the $100 repair bill would not bother you in the least.

Alternatively, the quick shutoff system DK refers to, on his mower, sounds very workable on a saw as well.

Hello IanR,

Just to say I completely agree with your post!

....Unbelievable......and they call that progress......

If you fit my version (would be cheaper and far easier in the long run) I would be most interested in your findings......You need something like this:-

Good job Andy!

I'd just add the connections to the coil, to guarantee it is powered by the same source as the saw. Of course if the coil has a different voltage than the motor, an appropriate transformer would have to be included.

"Of course if the coil has a different voltage than the motor, an appropriate transformer would have to be included."

-Or you could just use a dropping resistor. The small load of the relay coil wouldn't require one with too much power dissapation. Probably a little smaller and cheaper than a XFRMR.

Well done, but you neglected to include "THE BIG RED KNOB" to turn it off and the little green Knob to turn it on!!!....

(There nothing like a "BIG RED KNOB" to turn people things off!!!)

Seriously though, even a mechanical switch could be used provided the Off button is larger, more obvious and easily hit in an emergency with either hand.....some thought must be given to placement and type.......

Good point. If it were me, I would have a fourth NO (normally open) contact that one leg of the coil would have to flow through in series with a SPST NC (Normally Closed) momentary switch (the big red one). I would have another SPST NO switch in parallel with the fourth relay contact (the big green switch). That way when the green switch is pressed, the coil will be activated, pulling the fourth contact closed, thereby remaining activated when the green switch is released. then a momentary pressing of the red switch would de-power and unlatch the coil, disconnecting power to the motor and shorting the motor phases together to stop the motor dynamically.

Ideally the red and the green switches should either be far enough apart that they cannot be pressed together, or have a mechanical interlock such that only one can be pressed at a time. Another, better, idea is to have TWO green switches wired in series, an arms length apart such that it is not possible to start the machine without making sure both hands are away from the cutting blade. Both switches have to be pressed at the same time for the machine to start.

Some very good safety points, though using a table saw without having both hands available is probably not on.......not that I am an expert on such saws or their uses/method of use.....

Your system is certainly safe, but I believe overly complex. For a Band saw or Table saw, I think the two-handed ON switch is definitely overkill. It's not a stamping press or shear! I know if there were two hands required to start my saw (at home, where I don't have to worry about OSHA), one of the two switches would soon be disabled.

Safety protection is fine within reason, but frivolous lawsuits have made it be carried to extremes. What happened to individual responsibility? If you don't know how to operate a machine safely, then you shouldn't be operating it without close supervision. If I ever get so senile that I can't remember to keep my hands away from the blade while turning the machine on, then I hope I'll be wise enough to stop using it!

Here's a good compromise between safety and simplicity/economy:

(obviously still based on Andy' original drawing)

Dick

Hello LJ,

It is a real shame the safety device worked only once! Devices described by Andy and several other posts would work and be able to be reset?

I can understand why this safe saw did not catch on! Having to return it as you describe, is a complete nonsense!

I agree 110%.

Hi Andy,

I am not sure about the extra 10% over and above the necessary 100%, but I thought you may agree because you and others have put forward better resettable safety mechanisms! Perhaps you should get together to make a resettable device, and or, list the Invention ready for others to pay you to build it?

Its a welknown method of stopping most motors for many years, I would say that you could not patent it.....there many similar units available on the open market......

The rules and regs for selling such equipment are necessary, but not easy to follow.....I do not have the interest in fighting my way through them.......you could do it if you wished...

Hi Andy,

Fair enough! I realize the mix of that sort of gear. And, as you more or less say, it aint easy to find your way through!

Laughing Jaguar wrote:

"One of my more inquisitive friends went to the manufacturer of that table saw and discovered that the safety device only works once! At that point you must return the saw, at your expense, to have components replaced. The cost of doing so is over $100 and of course you must still bear the crating and shipping costs which are considerable. One doesn't see it anymore and, given my heavy involvement with shop tools, that suggests that it never caught on."

I have no connection with the company but they appear to still be in business. I was able to locate their site by entering "'Saw Stop" on Google. They also seem to have a number of dealers.