# Additional Informaton



## Mip (Sep 16, 2012)

I have been following this technology ever since it came out about 15 years ago. I remember reading something about the capacitance (I had to scroll up to get the right spelling) of the body to set off the brake since the body lowers the voltage. It is top of the line technology they have built in there, no doubt about it. I just wished they used the plastic brake instead of the aluminum one, the plastic doesn't damage the blade. Could you answer me this: why did Sawstop go with the aluminum brake? I did post this question to Sawstop, but no response. That was a nice present you gave your son-in-law, by the way.


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## bbasiaga (Dec 8, 2012)

Without being on the inside at SawStop, I can only guess that with plastic the heat involved with dumping all the energy of the blade into the break could lead to melting, even just small areas, which could then lead to the potential failure to stop. Also, mass must play a role in the inertial breaking of the blade, and a plastic insert of the same size as an aluminum one would likely weigh less.

There are a number of high performance plastics that may solve some of these problems (if they are even the problem), but then the cost could very realisitically be higher than aluminum.

-Brian


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## gtbuzz (Sep 19, 2011)

RegP - do you by any chance have a picture of the difference in cartridges with and without the tape you talk about? Did they really implement this design change on your suggestions? If so that's pretty neat and kudos for your contributions to the community.

Mip said: "Could you answer me this: why did Sawstop go with the aluminum brake? "

The very reason that the plastic brake would be much less likely to damage the blade is pretty much the same reason it wouldn't make a very good brake.

The aluminum in the cartridge is designed to absorb the energy in the blade in such a way that the blade can be stopped in time but also in such a way that it doesn't destroy the saw. Essentially, you've got to have something that is stiff enough that it can absorb the energy, but not so stiff that it simply transfers all the energy. If you look at the design of the cartridge, it operates in a very similar manner to a crumple zone in a car. Much of the energy is absorbed via the deformation of the cartridge.

I think plastic would have virtually no chance at stopping the blade effectively. In all likelihood the blade would just tear straight through or best case scenario, it would be a lot less effective. For comparison purposes, your standard 2024 aluminum alloy is roughly 20-30 times stiffer than ABS plastic, and about 3 times stronger. There are some fancy plastics that can match aluminum in strength, however even those still only have a modulus of elasticity that's an order of magnitude less than aluminum (and as Brian pointed out very expensive). You could technically design a plastic structure that's as stiff as an aluminum one, but it essentially would have to be 10-20 times thicker. In this case, you'd lose all the inclusions that are used for the crumple zone and the cartridge would just fail before it stopped the blade. Not good.


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## AlbertaJim (Oct 1, 2011)

Thanks for all the information. It helps explain why my saw didn't trip when I hit a nail last year.


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## Marty5965 (Jan 27, 2013)

When all is said and done, $200 bucks or so for a new cartridge and blade is way less than the alternate cost….right? Thanks for the detailed explanation Reg.


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## mbs (May 8, 2010)

I discharged the brake by having the riving knife BARELY touch the blade when the saw was running. There is no reason to have the riving knife that close to the blade. lesson learned!


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## RegP (May 4, 2013)

Thanks mbs I did not think of the knife touching the blade. Will check that out.

Re the plastic brake I suggestion by gtbuzz. I you were my student I would give you an A for the idea but having a university major in plastics myself some of the UHMW materials might come close but the cost and deterioration over time might be obstacles to overcome. Aluminum is not a bad choice in my opinion.

Yes we made the suggestion to Sawstop and I was pleasantly surprised at their reception to it. They immediately tested it and got back to us indicating that they say no problem with the tape as far as an undesirable effect and later when I accidentally tripped my own saw, I absentmindedly walked up to it to cut off a piece of 1 1/2 aluminum angle. I forgot to use bypass mode. It only hurt my wallet. I was surprised that the replacement had the sticker on the surface doing the job of the tape right from the factory.

The saw wont start if you are in contact with the blade. It wont start if you put in a dado pack without the dado brake. Brake is still active during coast down. Personal experience.

It works like a touch lamp electronically.

Some one asked how long it takes to change a brake. Not much longer than changing a blade it might add 2 minutes. Not a factor however a youtube of the procedure would be handy as you don't do it everyday.

I guess I am surprised at the interest taken in my post. When the dust settles and suggestions/questions get posted I would like to rewrite incorporating more information into this and check all my findings again just to be sure. At the same time possibly address some of the misinformation that people have heard.

I have never spoken to S. Gass but I believe what he has done was right, difficult, and needed. If my information is correct this was offered to all the major manufacturers and they all were cut off at the pass by their legal departments based on the premise of what happens if it doesn't work and someone loses a finger.
They would not even dare to risk manufacturing it. It took years and a great deal of money to bring it to market. The difficulties and personal sacrifice say to me it could not have been just for the money.

To put that in context imagine that we can't add seat belts to our cars because of the legal question of what if someone dies or is hurt while wearing one? That goes on and on. Accidents do happen to the best of us. The technology is available and prevents injury. I wish I had been able to come up with it but I am not sure I have what he had to persevere and see it through. I only hope someone will improve on this technology.


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