Motor brake question.

[Bernie Kopfer]

I have often wondered why manufacturers do not put motor brakes on equipment such as table saws and bandsaws. From a safety standpoint it seems like a no-brainer. Perhaps some of you electrical wizards can provide us with a good explanation.

[Malcolm McLeod]

I have often wondered why manufacturers do not put motor brakes on equipment such as table saws and bandsaws. From a safety standpoint it seems like a no-brainer. Perhaps some of you electrical wizards can provide us with a good explanation.

After very thorough analysis of the physics and engineering - a brake is too expensive. And it might reduce the manufacturer's market share.

[Warren Lake]

have a Short Stop on a radial, opened it up to see whats inside and there is lots. Cant see these things being cheap. STill have to price it out. Few adjustments in there as well. This was from a school so guess its mandatory there. have to wonder if in the length of the life of a motor how this affects it any extra strains.

[David Kumm]

The two types I'm familiar with are DC injections brakes and mechanical brakes. The injection brake needs to be adjusted to the mass of what is being stopped, has a certain number of stops per hour depending on size and heat sink attached, and in the case of a table saw, needs the arbor design to allow for quick stops without loosening the nut. My mechanical brakes depend on an arm that surrounds a heavy cast iron motor fan and is retracted when power is fed to the motor. Those are almost always broke or not adjusted correctly on a used machine. They are also often hard to get to which is why they aren't adjusted. Both add a fair amount of cost. Dave

[John Lanciani]

My J/P, table saw, and shaper all have electrically activated mechanical brakes. They all meet the EU standard of stopping all motion within 2(?) seconds of pressing the off button.

[Bill Space]

I have often wondered why manufacturers do not put motor brakes on equipment such as table saws and bandsaws. From a safety standpoint it seems like a no-brainer. Perhaps some of you electrical wizards can provide us with a good explanation.

Well, actually manufacturers do put brakes on table saws and band saws.

But it depends what you mean by brake. SawStop probably qualifies as a really fast acting brake if tripped.

My Grizzly table saw has a blade slow down function that stops the blade in about 5 to 7 seconds. Brake I guess not, but not too bad.

Some bandsaws have foot brakes or electronic braking.

So what do you mean by "brake?"

[Andrew Hughes]

My jointer has a break it just a little short handle that rubs to slow the motor. I hardly ever use it because it only takes a couple minutes for the head to stop spinning.
My bandsaw has a foot break.
Tablesaw doesn’t need one.

[Mike Henderson]

This is totally different size but I recently purchased a DeWalt cordless trim router. When I turn it off, it STOPS. Immediately. I don't know what technology they use - I'm sure it's electronic - but it's impressive.

Mike

[Bernie Kopfer]

Well, actually manufacturers do put brakes on table saws and band saws.

But it depends what you mean by brake. SawStop probably qualifies as a really fast acting brake if tripped.

My Grizzly table saw has a blade slow down function that stops the blade in about 5 to 7 seconds. Brake I guess not, but not too bad.

Some bandsaws have foot brakes or electronic braking.

So what do you mean by "brake?"

Should have been more clear. I was referring to some form of electronic braking. Not a person actuated mechanical brake. Since I know very little about how a electronic brake works, I was hoping for some enlightenment. Also did not know that EU machines had stopping requirements.

[Joe Calhoon]

The two types I'm familiar with are DC injections brakes and mechanical brakes. The injection brake needs to be adjusted to the mass of what is being stopped, has a certain number of stops per hour depending on size and heat sink attached, and in the case of a table saw, needs the arbor design to allow for quick stops without loosening the nut. My mechanical brakes depend on an arm that surrounds a heavy cast iron motor fan and is retracted when power is fed to the motor. Those are almost always broke or not adjusted correctly on a used machine. They are also often hard to get to which is why they aren't adjusted. Both add a fair amount of cost. Dave

Dave, this is timely as I want to put a brake on my Martin T17 saw. Right now it takes about 30 seconds to stop. I find this annoying and dangerous after using my T72 saw for 20 years that stops in less than 2 seconds. It has a Lenze electromagnetic brake. Not sure what the shaper, jointer and planer have. They take about 8 seconds and make that electromagnetic sound when stoping. Nothing in the manual about the brakes on those but the T72 has extensive details on the brake in the manual.

I know the pins on the newer saws are there to keep the blade from spinning loose. I’m thinking if I could stop the T17 in about 5 seconds this would not be an issue. Do you think a DC injection brake would be the way to go on retrofitting this? Adapting a electromagnetic brake to this saw seems like it could be difficult.

[Warren Lake]

Adding a brake at least one company is called Short Stop. Its been added onto the radial I have after the fact. Motion Industries I think is their distributor, they didnt give me a price when asked but referred me to Motion. There is lots going on inside the box. Meant to take photos last night will get them tonight so the sparkies can see what is in there.

[Joe Calhoon]

I looked up the Short Stop after you posted above Warren. Looks like a good way to retrofit. Is it adjustable for stopping time?

[David Kumm]

Joe, the short stop is a large stand alone box that you just incorporate in your start stop wiring. The smaller injection brakes that come on most new Euro machines are wired into the system. A stand alone add on either needs a contactor, or you can replace the existing starter with one that incorporates the brake unit. I didn't find a lot of choices in the US. Europe seems to have them for much less cost. I dealt with Sam Butler and Powerdrives in the UK. I can supply you with his email. Versibrake in Germany is also a source. You would want one that is either a little larger than the smallest model or one that has an exterior heat sink which increases the number of stops permitted each hour. I'm guessing 500-750 range for cost. Dave

[Warren Lake]

here is inside from an old photo not too clear, will take some tonight. Its a box on the saw ill guess at 4 x 9 x 9 but that is irresponsible guess as ive never looked at it thinking about its size, I have about moving it.

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[Joe Calhoon]

Thanks for the info Dave and Warren, very helpfull.
Dave if you could PM those contacts I would appreciate it.
joe

[Paul Stoops]

It would also be interesting to show a photo of the wiring diagram (inside the cover?).

Paul

[Warren Lake]

Short Stop box dimensions are 4 5/8" x 10 1/4" x 10 1/4".

On this radial its mounted on one front leg on the side.

Wiring Diagram shows hook up and set up with how to adjust it time wise. I dont have it running yet so now sure how the brake is adjusted. Likely this radial would free wheel for a while, even by hand spin it goes a while. Grew up without brakes on machines so used to that, realize some spin longer than others. Nice with brakes on shapers even if not electric, at least you can change your cutters right away and not wait for it to stop.

I think I asked if these gizmos has any wear over the long term on motors or bearings?


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[Rod Wolfy]

My old Felder had a12” blade, which had two pin holes that needed to be machines into the average Freud or whatever brand that I wanted to put on it. There was a motor brake on the saw and it stopped the spinning blade within 3 seconds. I came to really appreciate it. Same with the jointer/planer. I like it on the newer battery powered trim routers that I have too.

The scariest tools are the circular saws on a job site. A buddy was cutting window trim last summer. He sliced off 2” of his left index finger after he turned off his portable $150 table saw and turned to look at what the dog was barking at. It still pains him every day.