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  • Injuries from Flying Carbide teeth

    I don't know if starting a new thread is a good idea or not but anyway...

    Looking at that untoothed Blue Thunder blade that Ryan has showed made we wonder about injuries when this type of catastrophe occurs.

    On the other hand, has there been any kind of reported injuries with flying carbide embeding in people? I wonder if these flying pieces have the kind of momentum to actually cause piercing of the skin. (My guess is that they would not)
    What is the knowledge out there about this?
    -------
    Cheers,
    --Rick
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  • #2

    Re: Injuries from Flying Carbide teeth

    Re: Injuries from Flying Carbide teeth

    Originally posted by Rickbird View Post
    I don't know if starting a new thread is a good idea or not but anyway...

    Looking at that untoothed Blue Thunder blade that Ryan has showed made we wonder about injuries when this type of catastrophe occurs.

    On the other hand, has there been any kind of reported injuries with flying carbide embedding in people? I wonder if these flying pieces have the kind of momentum to actually cause piercing of the skin. (My guess is that they would not)
    What is the knowledge out there about this?

    I'll ask the boss -- she sees a lot of the nail gun and table saw users professionally -- mostly nail gun users -- so don't pull the plug on your table saw yet.
    ---
    Will

    “There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.” —- Mark Twain

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    • #3

      Re: Injuries from Flying Carbide teeth

      Re: Injuries from Flying Carbide teeth

      My guess is that teeth that are ejected from the blade are ejected the same place the sawdust is going... which is generally not at the operator. Unless the tooth comes loose at a point when it is not striking the object being cut (seems unlikely).

      Nevertheless, there is a general safety rule to never stand directly in front of a vertical cutter. Good one to follow in my opinion.

      Cheers,

      Mike

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      • #4

        Re: Injuries from Flying Carbide teeth

        Re: Injuries from Flying Carbide teeth

        I,ve fortunately never had any experience with teeth coming out of sawblades, but about a month ago I was routing some maple stair stringers & I snapped off a 1/2" routerbit. My Makita 3612? I think has 22,000 rpm. Within a second of the bit snapping off, the cutter portion of the bit was laying lifeless in the treadspace. It barely moved from where it snapped!

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        • #5

          Re: Injuries from Flying Carbide teeth

          Re: Injuries from Flying Carbide teeth

          I once asked a supplier of brush trimmer blades why I could not use a normal saw blade instead of their 1" arbour blades.

          The reply was that people would use carbide blades and injure themselves. Probably.

          I have had carbide teeth disappear from table saw/radial arm blades, and a circular saw blade, and never knew where they went.

          If they came free at full speed, they would almost certainly penetrate the skin. I believe the rim speed is nearly 9000 feet per minute, or 300 feet per second.

          According to:

          http://www.velocitypress.com/air_rifle_ballistics.shtml

          the velocity of a .22 rifle drops to 400 fps at 70 yards.

          And the carbide tooth is sharper than a 22 bullet. Ouch!
          In an age when scientists are creating artificial intelligence, too many of our educational institutions seem to be creating artificial stupidity. - Thomas Sowell

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          • #6

            Re: Injuries from Flying Carbide teeth

            Re: Injuries from Flying Carbide teeth

            I have been Machining for 30 Yrs. Carbide Breaks quite easily,and can come at you fast enough to kill you, dont underestimate what any kind of broken tool HSS or Carbide can do.
            • “The greatest lesson in life is to know that even fools are right sometimes.”Winston Churchill

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            • #7

              Re: Injuries from Flying Carbide teeth

              Re: Injuries from Flying Carbide teeth

              Originally posted by Gene45 View Post
              If they came free at full speed, they would almost certainly penetrate the skin. I believe the rim speed is nearly 9000 feet per minute, or 300 feet per second.

              Of course I was using my new Apple clock that runs on Quicktime, only 30 seconds per minute.

              The right answer is 150 fps. So Sorry!
              In an age when scientists are creating artificial intelligence, too many of our educational institutions seem to be creating artificial stupidity. - Thomas Sowell

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              • #8

                Re: Injuries from Flying Carbide teeth

                Re: Injuries from Flying Carbide teeth

                A table saw motor usually rotates at 3450 RPM. With a 10" blade, the outer speed of the blade is roughly 102 miles per hour. Given the light weight of the carbide, it is unlikely that it would cause more than an abrasion or bruise - very unlikely to penetrate your skin or clothing. It will, however, damage your eye.

                According to the interweb, a Colt 45 fires a bullet at approximately 550 miles per hour, while a .22 caliber handgun fires at over 2000 mph.

                As a further reference, raindrops fall at around 20 miles per hour and a large hailstone can fall at approximately 100 miles per hour.

                All that said, several years ago, I dropped a very small piece of wood (I believe it was poplar and maybe 1/2" x 1/2" x 1/2") on my spinning table saw blade. It hit the blade, bounced up and hit my left index finger, right on the middle knuckle. It hurt like he77, and to this day, my finger does not bend properly and still has minor pain.
                "Time is a great teacher, but unfortunately it kills all its pupils."

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                • #9

                  Re: Injuries from Flying Carbide teeth

                  Re: Injuries from Flying Carbide teeth

                  I have seen (as many of you have) pictures of kick back resulting in a hold in a block wall. I doubt the carbide would fly off with any less force then a piece of wood gets kicked back. A tooth could (in theory) get damaged while in the wood and not break free right away. If it breaks free when it's traveling toward you, it will travel in a straight line...toward you.

                  A number of years ago there was a similar thread on this forum. One of the members related a story of a friend who was hit in the leg by a piece of carbide that broke off a router bit. The fragment entered his leg and severed the main artery (or is that a vein?). The poor guy bled to death before anything could be done. IIRC this happened on the job and there was immediate aid but there was nothing anyone could do. Sad story.
                  J.P. Rap Mount Hope Ont.
                  Carpe Ductum (Seize The Tape)


                  "In this world, you must be oh so smart, or oh so pleasant." Well, for years I was smart. I recommend pleasant. Elwood P. Dowd

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                  • #10

                    Re: Injuries from Flying Carbide teeth

                    Re: Injuries from Flying Carbide teeth

                    Originally posted by J.P. Rap View Post
                    A number of years ago there was a similar thread on this forum. One of the members related a story of a friend who was hit in the leg by a piece of carbide that broke off a router bit. The fragment entered his leg and severed the main artery (or is that a vein?). The poor guy bled to death before anything could be done. IIRC this happened on the job and there was immediate aid but there was nothing anyone could do. Sad story.
                    IIRC it was a piece of wood from kickback that pierced the artery in the person's stomach. There may have been another one where a splintered board from kickback pierced an artery in the individual's leg. They were posted on other forum as well.

                    The mitigating factor that would likely (and I say likely) prevent carbide from penetrating is the weight.

                    Again, I'm saying likely - so make sure to be safe.
                    "Time is a great teacher, but unfortunately it kills all its pupils."

                    Comment


                    • #11

                      Re: Injuries from Flying Carbide teeth

                      Re: Injuries from Flying Carbide teeth

                      Rickbird, I think this is a great topic to start. As woodworkers we should all be aware of the dangers of the hobby, and sharing experiences about such incidents as carbide teeth flying off saw blades is valuable to all.

                      I looked at the manual and found that the no load speed of my 12" Bosch miter saw is 3800 RPM. Using this site:
                      http://www.sharptool.com/reference_tables.html#RimSpeed
                      I figured that a 12" blade at 3800 rpm, the rim speed is 11938.11 feet/minute.

                      Using this site:
                      http://www.convert-me.com/en/convert/speed

                      I converted that to more common measurements of velocity. The teeth of my saw will spin at 199 feet/second = 135.7 miles per hour = 218.3 kilometers per hour.

                      Not quite the speed of a bullet, but pretty darn fast. Of coarse that is no load speed, so add a load, and it slows down. Then consider the fact that the teeth likely hit wood before or during flying off (in my case), then they probably would have slowed down more.

                      I don't know exactly what injury I may have sustained if the teeth or even the wood splinters had hit me, but I'm sure glad I didn't find out.

                      But I sure think it is worth it to spend the money on a higher quality blade where the processes for making the blade and attaching the carbide are likely better and more strictly controlled. Hopefully that seriously limits the chance of carbide coming off or entire teeth breaking at the gullets. I've always said, you get what you pay for, and I guess it was wishful thinking to think a $55 12" blade would hold up much better that it did.
                      Today I spent $160 on a new blade from a reputable industrial blade supplier. I'm excited to see the difference quality makes.

                      Ryan

                      Oh, if down the road someone has no idea what I'm talking about, here is my other thread. http://forum.canadianwoodworking.com...ad.php?t=27978

                      GALLERY OF PROJECTS: http://lumberjocks.com/galleries/Boomr99#

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                      • #12

                        Re: Injuries from Flying Carbide teeth

                        Re: Injuries from Flying Carbide teeth

                        Originally posted by Max In Sudbury View Post
                        IIRC it was a piece of wood from kickback that pierced the artery in the person's stomach. There may have been another one where a splintered board from kickback pierced an artery in the individual's leg. They were posted on other forum as well.

                        The mitigating factor that would likely (and I say likely) prevent carbide from penetrating is the weight.

                        Again, I'm saying likely - so make sure to be safe.
                        Those might be different guys. I clearly remember it was a piece of carbide from a router bit.
                        J.P. Rap Mount Hope Ont.
                        Carpe Ductum (Seize The Tape)


                        "In this world, you must be oh so smart, or oh so pleasant." Well, for years I was smart. I recommend pleasant. Elwood P. Dowd

                        Comment


                        • #13

                          Re: Injuries from Flying Carbide teeth

                          Re: Injuries from Flying Carbide teeth

                          Every once in a while I get photos and descriptions of injuries in woodworking. Last summer one of those injuries was of a man who dropped a wrench he was using to adjust his miter gauge attachement. The wrench glanced off of the miter gauge fence and directly into the spinning table saw blade. Several teeth were sheared off and two lodged in his forehead, penetrating the skin far enough that they had to be removed in the hospital. One required opening the wound a bit by the doctor (cutting) to get at the broken tooth to remove it.
                          I never put photos like that on my site because I have agreements with many schools and lots of family-type viewers. But I think it is important that we never assume something probably won't hurt us that bad. Given the right situation - which always happens at exactly the wrong time - just about anything we use in woodworking or anything else really can hurt us.
                          Best not to tempt the evil woodworking spirits!
                          Tom Hintz
                          NewWoodworker.com

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                          • #14

                            Re: Injuries from Flying Carbide teeth

                            Re: Injuries from Flying Carbide teeth

                            Originally posted by Tom Hintz View Post
                            Every once in a while I get photos and descriptions of injuries in woodworking. Last summer one of those injuries was of a man who dropped a wrench he was using to adjust his miter gauge attachement. The wrench glanced off of the miter gauge fence and directly into the spinning table saw blade. Several teeth were sheared off and two lodged in his forehead, penetrating the skin far enough that they had to be removed in the hospital. One required opening the wound a bit by the doctor (cutting) to get at the broken tooth to remove it.
                            I never put photos like that on my site because I have agreements with many schools and lots of family-type viewers. But I think it is important that we never assume something probably won't hurt us that bad. Given the right situation - which always happens at exactly the wrong time - just about anything we use in woodworking or anything else really can hurt us.
                            Best not to tempt the evil woodworking spirits!
                            So the guy was making an adjustment with a wrench while the saw was running??? Thats just plain foolish.

                            I'm not surprised though that the teeth easily penetrated his skin. There was some suggestion that they wouldn't. I suppose it would depend on where on the body they hit. My cushy stomach might give a little more than my forehead, so the teeth may not penetrate with less resistance behind the skin (i.e. flab vs. skull). The days of my rock hard 6 pack are gone....

                            Ryan

                            GALLERY OF PROJECTS: http://lumberjocks.com/galleries/Boomr99#

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                            • #15

                              Re: Injuries from Flying Carbide teeth

                              Re: Injuries from Flying Carbide teeth

                              My cousin used to own a circular sawmill - something in the 52" diameter size, run by a Cockshutt tractor. Between the operator and the blade hung a sheet of cloth mesh - something like a burlap window screen. Every once in a while, one the insert carbide teeth would work loose and come flying out. If it happened to come in the direction of the operator it would hit the cloth and fall to the ground. I saw a couple hit the cloth and they never came through. I'm not saying it isn't dangerous, I'm just saying that wearing the correct work-wear, safety gear etc. is a good idea.

                              cheers

                              john

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