Sunday, May 4, 2008

Let's Talk About Table Saw Safety

Welcome to Woodworking Safety Week at Tony’s Woodshop! As a member of the Wood Whisperer Network, I’ve decided to participate in this important event and include a post or two about working safely in your shop. It’s important to remember that the tools we work with, especially power tools, are equally capable of cutting through flesh and bone as they are of cutting through wood. If you’re at all attached to your fingers (pun intended), you need to use safe practices whenever you use any tool. Remember, the tool can’t hear you scream!

So first, I want to talk to you about an injury I had about 4 or 5 years ago while using my table saw. I’m going to describe what happened first, then I’m going to discuss how the whole thing could have been prevented.

At the time of this accident, I had a Craftsman bench top table saw. I had received the saw as a Father’s Day gift the previous year and I was still very excited about owning it. I had just joined the WoodNet forums within the past year, so I was very excited about making things using all of the techniques & tips I had read on the forum.

As with all table saws in this class, the saw had a universal motor that was connected to the blade by a “direct drive” mechanism. There was actually a belt & two pulleys in a little plastic box that connected the motor to the blade, but you could still bog that saw down without trying too hard. And I even managed to do it once or twice.

I used to keep this saw in my tool shed and carry it outside when I needed to use it. Yes, I used to literally pick it up & carry it. It only weighed about 70 or 80 pounds. I used to set it up in the backyard about 10 feet or so in front of the shed. I worked out there so much that year that I wore down a bald spot in the lawn in that area.

I had decided to make a crosscut sled for this saw. I used a plan that originally appeared in an issue of Woodsmith or ShopNotes. I found it in a book that was sent to me as a gift for subscribing to Woodsmith magazine called “The Ultimate Jigs & Fixtures Book”. It had replaceable inserts for making beveled or 90° cuts and a secondary fence for making mitered cuts. It looked like a good design to me, so I built it.

I had reached the point where I had to make & attach runners to the bottom of the completed sled. Even though the plan called for just one runner, I wanted to put two on the sled. My reasons were based on some posts I had read on WoodNet arguing that double runner sleds stayed more accurate year round despite temperature changes. This was good enough for me.

So I got started making the two runners. But there was a problem.

The saw’s stock miter gauge was both substandard and nonstandard. It was nonstandard in that the miter bar & the miter slots were oddly sized & shaped. As you can see in the drawing at the right, the bar was shaped like an upside down “T”. It was also less than ¾” wide and less than 3/8” tall. But these were the slots the saw had, and I needed to make runners for the sled that would fit into those slots.

So I took a 3/4” thick oak board I got from Home Depot & ripped off two pieces the width of the miter bar, plus a hair more. I wanted to make sure these runners fit into the slots snugly. Then I turned the pieces on edge & ripped them to the proper thickness. Lastly, I lowered the blade so it was 1/8” high & set the fence to cut the corners away. The rabbets I had to make were less than a blade width wide, so I only had to make one pass per rabbet.

As I cut the rabbets, I found that the stock rose up & I didn’t get a consistently deep cut along the length of the runner.So I placed my left hand right over the blade, with the stock between the blade & my fingers, and pushed down while pushing the stock through. I even used my left hand to pull the stock backwards over the blade once or twice to make sure the blade cut full depth.

Well, I got away with this once or twice, but then it happened. The blade teeth caught on the runner stock & shot it out of there like a bullet.I later found the runner about 25 feet away from the saw in the back of the shed. So even though it was an underpowered saw, it had quite a kick.

When the stock disappeared from under my hand, my left thumb contacted the blade. Lord, did that hurt! I remember feeling the blade’s teeth passing through the spot where flesh had been. And it hurt, a lot! I’ve felt worse in my life, but this is something I never want to experience again.

I grabbed my thumb, somehow shut off the saw, and went inside. Luckily, the blade was only 1/8” high, so I didn’t cut anything off except some skin & the corner of my thumb nail. And I didn’t have to go to the emergency room. I just cleaned it, put some gauze on it, and wrapped it in adhesive tape. And went back to work on the runners.

The good news is everything healed & grew back normally, though I do have a 1/2” or so long scar on that thumb to remind me of my mishap. But how did this accident happen in the first place? There were a number of things that went wrong, all of them my fault & preventable. So let’s analyze what I did wrong.

  1. First, I ripped the two runners from the stock and then milled them. These pieces were much too narrow to safely mill them like I did. What I should have done is:
    • Ripped a piece at least 2” or 3” wide off of the oak,
    • Ripped that larger piece to thickness, or even better, if I had owned a thickness planer at the time, I should have planned the piece to thickness.
    • Next I should have cut the rabbets, and finally,
    • Rip the two runners off of the bigger piece.

    The larger piece would have kept my hands farther from the blade and so could have been worked much more safely than the two narrower pieces. With the narrow pieces, my hands were just too close to the blade.

  2. When I found that the rabbets weren’t being cut full depth, I should have attached a feather board to my fence to hold the stock down instead of using my fingers. If the board kicked back with the feather board in place, my hand wouldn’t have been in danger of falling into an exposed blade.
  3. Third, never ever run stock backwards through the blade! Of all the things I did wrong, this was by far the stupidest. The other two things I did wrong I can put down to having been a newbie and not knowing any better, but even the saw’s manual tells you not to do this. And I always read the manual whenever I buy a new tool. I knew better, but I got away with it a few times & the warning just flew right out of my head.

Finally, I got lucky. It was pure dumb luck that the blade was only 1/8” above the table when my thumb dropped into it. It was pure dumb luck that the blade only cut through the fleshy part next to the nail. This injury could have been a lot worse. As it was, it took over a week for the throbbing to stop, and close to two months for it to heal to the point that just bumping it into something didn’t hurt any more.

This wasn’t the worst injury anyone has ever suffered while operating a table saw, but it was the worst one I’ve ever received. And now, when I’m thinking of using my table saw to make a tricky cut, I listen to that little voice in my head that tells me “don’t do it that way!” I use feather boards when they’re called for, and I always use a push shoe if my hand is going to be within the “red zone” (that area where the throat plate sits. It’s painted red, so it’s the red zone).

As Sgt. Estherhouse used to say on “Hill Street Blues”, let’s be careful out there!

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