Safety Warning

[Hendrik]

Hi, everyone:

Sorry I haven't been on here lately. I've been working mega hours, six days a week (sometimes 7!) since Christmas. Only now do I see the light at the end of the tunnel, and I feel like I'm kind of climbing out of a cave to find out what I've been missing.

I just emailed everyone on my private emailing list with a safety warning and I thought some of you might appreciate me posting it here. Here it is:

Hi, everyone:

I wanted to get this safety warning out to everyone right away, in the hopes I might prevent an accident.

Some years ago, someone who frequents my seminars accidentally knocked one of my table saw blades off its holder on my lumber rack. Just got his coat caught on it, or something like that. Anyhow, the blade landed tooth down on the concrete floor and I immediately discovered that one of the carbide teeth had broken off. I found the tooth on the floor. Now, any good sharpening service would have reattached the tooth back to the blade, and some of the other participants at the seminar mentioned that. My worry, though, was that other teeth may have also hit the floor, weakening the bond between carbide tooth and blade. Without a way to know for sure, I wasn't willing to compromise my safety (or the safety of my students) for the sake of a $50 blade. I decided to throw it away and buy a new blade.

Just a couple of seminars ago, one of my regulars asked me a similar question. It seems he dropped a blade on the floor and one of the teeth got chipped. It didn't break off completely, but just chipped part of it off. He asked me if he could just go ahead and continue to use the blade as-is, on the theory that one of 80 teeth wouldn't make much of a difference to the cut. I agreed that it would still work, but I cautioned him about the possibility that the chipped tooth, or some of the other teeth near it, might have been impacted enough to weaken its bond. I told him to throw the blade out and buy a new one. It's just not worth the risk.

I don't know if he followed my advice or not, but I just got off the phone with someone from New York City inquiring about taking a course here in the summer. I explained how I do things and that safety is a big part of my courses. He then proceeded to tell me how a woodworking instructor with which he was taking a course was cutting on the table saw, demonstrating in front of the whole class, when a carbide tooth suddenly broke off the blade and hit him square in the forehead. He was wearing goggles, but the tooth went higher than that, becoming imbedded in his forehead. Surprisingly, it didn't go in very deep (not to his brain, at least!), but it was a shocking site for everyone in attendance. He said he'll never forget it. The blood that was gushing out of his forehead was enough to make your knees weak.

So what happened? Manufacturer's error? Maybe. But there are other possibilities. Maybe one of the students in the class dropped the blade on the concrete floor or banged one of the teeth hard on the table saw top. Without even thinking, he or she just put the blade away and was just glad nobody noticed.

Nobody will ever know what happened or who was at fault. But I'd suggest that you really think about these things before you put abused tooling in a machine. A carbide tooth flying off a spinning blade is like a tiny bullet, probably moving at well over 100 mph.

Anyhow, this horrific story was timely given the person's question at my recent seminar. And I just wanted to share it with all of you. It might save you from an accident one day.

Stay safe!

Best wishes,



Hendrik Varju

[George Matthews]

when a carbide tooth suddenly broke off the blade and hit him square in the forehead. He was wearing goggles, but the tooth went higher than that, becoming imbedded in his forehead.Hendrik Varju

I suspect that if the blade guard was in place there wouldn't be much of a story.

[Brent in Montreal]

Hi Hendrik,

Thanks for posting that. I always toss any suspect blade just on principle. The idea of a tooth flying at me is plenty to overcome the frugal Scot in me. There are enough things that can go wrong in the shop without adding to it by trying to save a buck.

[Hendrik]

Yes, George, I suspect there wasn't a blade guard on. He didn't say. I'll ask him again if he comes to my workshop this summer. If there had been a blade guard, I would guess that the carbide tooth would deflect downward at the front of the guard where it curves down. Then either just clear the table or bounce up off the table. It would probably hit the operator in the stomach area.

Maybe this guy was lucky to have lots of bone in his forehead to stop the bullet. If the deflection off the blade guard didn't slow it down a lot, I suppose the carbide tooth might penetrate pretty deep into your body. I remember reading about an accident once where a carbide tooth went directly through someone's heart and killed him. Extremely rare, of course, but you just can't predict something like that.

Cheers,


Hendrik

[billh]

When I bought my Exaktor over-arm blade "cover", one of the points the salesman kept making was about it stopping flying carbide teeth.

Another reason, even if a rare one, to use a guard.

Thanks for posting this. I think there are a lot of people who would risk using a dropped blade, particularly if they didn't see any obvious damage. This should make them think a lot more about the risk.

[Jim Shaver, Oakville Ont.]

Thanks for posting this Hendrik!

[MikeB]

To be honest I don't know if it would have occured to me to toss a blade if it didn't sustain obvious damage in a drop. Luckily I've never dropped one, but now I know...thx for the post.

[Grant in NW Quebec]

Concerns me too - my Rockwell Beaver doesn't have a guard nor a splitter. Every time I start it up I stand offside, but I'm thinking of doing something soon, as every now and then I find a tooth missing. Grinding wheels are dangerous too. When I was in the mining business I learned of one bit sharpener in Chibougamau took a piece of vitrified wheel in the gut and died of it. Vitrified (glass) bonded wheels which we mostly use for sharpening have a maximum rim speed of 6500 FPM which works out to a little over 70 MPH. Haven't done the math on saws yet but they're much higher than that. Better to be safe than sorry, huh?

[Randy in Calgary]

There are many hazards in our hobby. But freak accidents can happen in many activities. At the risk of ridicule, I'll share what happened to me last summer while playing golf.

I was on the 13th fairway at Priddis Greens, a nice course south of Calgary. I was playing pretty well, 11 over after 12 holes from the back tees. My ball was in the low cut of rough, just off the fairway about 155 yards from the green. There was a tree about 30 yards away with limbs overhanging the fairway. To keep my ball below the limbs, I selected a 5 iron and choked up on the grip a bit. I hit my shot, but the long grass pulled the clubhead to the left. The ball came out low and left, and hit the 150 yard marker (a small football sized rock) which was about 5 yards away. I actually did not even notice it there, as it was not in my intended line of fire. It rebounded and struck me directly between the eyes. It happened so fast, I didn't see it coming or have time to react. I went down like a sack of potatoes. Rising up to my knees, I saw the blood just pouring out of my face onto the ground. Luckily, the cart girl was driving by and my teammates got some ice from her to put over my face right away. 6 stitches (and who knows how many hairline fractures later) I was home eating tylenol like candy. I dread to think what would have happened if it had hit me in the eye, or in the forehead. The picture was taken well after the swelling and black eyes had subsided.

http://i43.photobucket.com/albums/e397/hrgillard/DSC01702.jpg

Should I now wear safety glasses while golfing? No, but I will never use a blade that I drop on the floor!

[Hendrik]

Thanks for sharing that, Randy. When I was in my late teens, I smashed a drive into a tree about 10 yards ahead of me and to the left. It bounced back, hitting one of my friends about an inch from his groin area, in the upper leg. No serious injury, but really lucky.

Not long after, someone else did the exact same thing. But this time, the ball bounced directly back at him and hit him square in the forehead. He collapsed to the ground, holding his head. Surprisingly, he decided to continue on with the game. No broken skin or bleeding. Just a massive bruise and a sore head.

Cheers,


Hendrik