Safer Saws
 

Hey,
In the interest of safety, my team (1452) has been looking into the different safety technologies that can come with saws, metal cutting band saws in particular. I was just curious if any one knew about good options.

Thanks

Re: Safer Saws
 

I recommend a blade with about 10-15 teeth / inch, this helps prevent large shavings and stalling of the motor.

Re: Safer Saws
 

I think the best way to be safe is to teach the proper safety practices and enforce them strictly. Make sure blade guides aren't too loose, make sure the blade guard is close to the top of the material you are cutting, use a fence for parts, use a good blade, tension the blade properly, etc. You can sometimes use a plastic or wooden piece to push parts through the blade to avoid getting fingers close to the blade. And obviously make sure the blade you are using is appropriate for the material you are going to cut.

Everything here - http://www.cs.rpi.edu/twiki/pub/Robo...dsawSafety.pdf

Re: Safer Saws
 

For cutting what, exactly? Different materials--even down to aluminum and steel--generally need different tooth counts. (Use of a single blade for multiple types of material will work--but the blade won't last nearly as long.)



Answering the OP question: #1 safety measure is a push stick of some form. It's best if you can get one that will work with the saw... Hard to describe, but most bandsaw tables I've seen have a groove for a push piece; this helps get a straight cut. Otherwise, a longish stick of wood will probably work. (For some jobs, you may be able to hold the material way out to either side in lieu of a push stick, but that's not a guarantee of a safe cut.)

#2, make sure the guide wheels on the blade are adjustable, and work. They'll usually pull a guard down to the material cutting, or just above, which definitely helps safety.

#3, regular inspections of the saw blade, and if you have a blade welder, only trained folks get to use it. Keep that blade in top condition--you don't want it to suddenly break on you.

Re: Safer Saws
 

Its pretty simple:
Right blade (designed for metal with the tooth count previously mentioned)
Right tension (depends on the blade and the saw)
Right speed (100 ft/min is a good starting setting for metals)
Guard as low as practical (expose the minimum amount of blade)
Hands behind the work (leave the shop with all 10 fingers in good shape)
Lubrication (particularly on steel)
Patience (metal cuts take time)

...that and a knowledgeable adult and you have all you need for a safe and productive saw.

If your band saw is of the horizontal variety add:
Set the feed rate damper properly
Check the clamp so the work is held securely
Test the shutoff switch daily

Re: Safer Saws
 

Most of the accidents and safety issues won't come from not being super-experienced with different types of saw blades (our team isn't), but instead because somebody tries to do something the fast way and does something silly.

It's really important to emphasize safety, especially when cutting metal on a chop saw. We had an adult hurt themselves (not badly) while cutting a piece of box tubing on a chop saw. To save time, he didn't bother replacing the blade missing a tooth. He amazingly made it through about 10 cuts before something went wrong.

Re: Safer Saws
 

Or you can have a self destructing table saw

Re: Safer Saws
 

Like others have posted, get a purpose-built machine for metalwork with the proper blade. Keep the machine properly maintained ::rtm:: and make sure everyone is vigilant about safety and using the proper technique.

Re: Safer Saws
 

I see no one has suggested the ultra safe SawStop. While it can't cut metal or anything wet, I have told everyone, while giving tours of our shop, that it is "the safest table saw in the world".

Re: Safer Saws
 

I believe the link I posted was a saw using that technology.

Re: Safer Saws
 

Sorry, I'm at school, and they block youtube here.

Re: Safer Saws
 

Some of our students tripped the sensor on our school's sawstop table saw one year. They were getting ready to rip a 4'x8' sheet of plywood into strips for bumpers. First couple cuts were fine then there was a loud bang and the saw shut off. It took us a moment to figure out what happened, it apparently the piece of plywood from <large chain home improvement store> was still a little too damp and that tripped the sensor.

A new blade and a few days of curing in the shop later we were finally able to cut the rest of our bumper strips..

Re: Safer Saws
 

Just say Home Depot*!

*other brands are available

Re: Safer Saws
 

Eric, Akash, and Jeff all brought up great points. I'd just like to add to their comments. What I think is just as important as the hardware you have- like a miter gauge or sharp blade- is the skill and knowledge of the student using the machine. Make sure they understand how to use whatever push stick/miter gauge that you have. They should also know how to adjust the tension of the blade properly and the height of the guard. My point is that it doesn't help to have just one student who knows how to do these things, and the shop will be a far safer place if everyone using the bandsaw understands how to use it correctly. It doesn't matter if you have the best technology, if you have a clueless fabricator, you'll have a dangerous shop.

Re: Safer Saws
 

Another important safety tip for saw, drills, lathes and milling machines: never wear gloves while operating these tools!

If an injury occurs, wearing gloves will make it significantly worse. While a drill bit or saw blade will chop through your flesh easily, it can and will snag on the fibers of gloves and pull your hand further into the blade, thus causing a much worse injury.

Re: Safer Saws
 

Another similar point is to keep Everything out of the saw or drill area. These include neckties (some teams are classy), scarves, long-sleeved or loose clothing, long hair (tie it back!), and for a guy on our team last year, long beards.
If these get caught in the drill, saw, etc., then they will pull your face/arms into the drill, saw, etc., and really hurt you.
Just remember, keep everything away from the actual tool except the item to be cut, and wear those safety goggles!

Re: Safer Saws
 

This kind of cool concept just came to me:
Ground the blade of the saw. Have the student grounded. If there is continuity with the student and the blade, shut down the motor immediately. That can be a lifesaver for someone who falls asleep while cutting something.

Sorry for the caps, below:
THE MOST IMPORTANT:
AS MENTIONED BEFORE, MAKE SURE EVERY STUDENT IS TAUGHT SAFETY COMPLETELY.

In our school, we are required to take safety tests, which makes me think, maybe that is what I should do, if I become team captain, before I will allow someone to use the tools!

Re: Safer Saws
 

A lot of you might think this is a weird thing to bring up, but, what about rules, in the sense:
If you have any hair of a certain length or greater (e.g. 6 inches head, 1 inch mustache/beard, it must be secured and held back or cut off to use certain tools. Nothing's worse than getting a strand of hair stuck within a drill's air intake!

Re: Safer Saws
 

Has this been an issue for you?

Re: Safer Saws
 

That was a bit sarcastic, but some extreme cases commonly happen, especially is someone is distracted!


Also, this also just came to me, a vision tracking program watching the user's eyes, making sure they are continuously looking at what they are machining. Seems like a lot of work, but if someone builds one and gets it into production, it can change the lives of workers around the world!

Re: Safer Saws
 

Everyone on our team is required to have a 10-hour OSHA certification (school funded, unless you fail) to do basically anything in the lab.

Re: Safer Saws
 

You kinda just described a SawStop, of course it stops the blade a lot faster then 'shutting of the motor'. Which reminds me of this neat video about it.

Re: Safer Saws
 

I didn't know that! However, the SawStop works in a different way!

Re: Safer Saws
 

You do realize if you ground the blade & the student you are going to have continuity between the 2? Saw will not start using that scheme. Which will keep it safe, but useless. :]

Re: Safer Saws
 

^this. Good idea, though!

Re: Safer Saws
 

Actually, what I meant was to have a current, probably 12v, 2.5ma being conducted through you. Since this is an open circuit, nothing will flow through you. When you touch the blade, the circuit will be completed and fed into a multi-stage amplifier. This will be fed into a flip-flop that will shut down the motor and arm the brakes, immediately. The machine will shut down and will be "hard" to turn back on (Require that the fault is cleared, etc.)

However, the problem is: if you are machining aluminum, it would automatically trigger, meaning that you would need to measure resistance. I do not see how the SawStop works with metals!

Re: Safer Saws
 

They said in the video I posted (see above) it detected the moisture in your hand. I don't know if that was just layman's terms though.

I had a lamp once that turned on by detecting when you touched it (anywhere in it's metal frame). I think it worked because your body acts as a radio antenna, and it could detect the signals to turn on.

Re: Safer Saws
 

Just thought of something.

Why would you be cutting METAL with a WOOD blade? However the SawStop works, I guarantee it requires an all metal blade, and will not work with an abrasive ceramic blade, especially since a ceramic blade would probably explode instead of fall through the table (turning a lost finger injury into a horrific shrapnel injury)

I've never seen a metal, metal cutting blade for a table saw.

Re: Safer Saws
 

This is exactly what happens with a SawStop cutting aluminum. Apparently there's a disable switch for the safety sensing. Ask me how I know...

Re: Safer Saws
 

I agree. It is a bad idea to cut metal with a wood blade. However, how does the capacitance cause such a change? I think that there is something being hidden from us. Also, with that little voltage difference, wouldn't there be quite a few false alarms?

Re: Safer Saws
 

I should mention that I find it completely acceptable to cut aluminum with a carbide tipped wood blade. Sometimes a little WD40 helps a lot too. I do this all the time in miter and circular saws without any issue, so long as you go slow and wear proper safety gear. I've even cut aluminum box (and solid) with a 24 tooth blade, although something like an 80 tooth would be preferred.

Re: Safer Saws
 

Getting a little off topic, does it help to use a blade with more teeth to cut metal? Doesn't bigger teeth just end up tearing metal?

Re: Safer Saws
 

The SawStop does not work with metals, nor Carbon Fiber. As mentioned there is a way to temporarily disable it. I've had to change a couple of cartridges from people attempting to use it for those materials.

The number of teeth that is optimum depends on the metal and the thickness of the metal. The harder the metal (steel) the more teeth, the thicker the material the lower the number of teeth.

Re: Safer Saws
 

That makes sense. Thanks for elaborating!