Bad weekend - two kickback episodes

[Gary]

This weekend wasn't a good one for me and the Unisaw. The darn thing kicked back twice. The first was my fault, the second, I don't know.

Saturday, I was building some drawers. I had removed the guard and splitter in order to cut some thin dados for the drawer bottoms. Next I attempted to cut a 4X8 sheet of 1/4" Luann for the bottom. I thought its just light weight Luann. First cut, an approximately 2'X4' cut off the end. Whamm! The 2X4 sheet went sailing across the room, Bam!!, stuck in the window casing behind my saw. Nice M&T embedding in the wall. Luckily I was standing to the left of the blade and it missed me.

Sunday morning, gluing up the drawers, I needed a 4"X6" block of 3/4 ply. Guard in place, I attempted to cut the piece off a 12" piece of scrap. (Should have used the miter saw). Still shaken from yesterday, I stood well to the left of the line of fire. Using the fence on the right and push stick, I started the cut. The piece on the right between the blade and fence fed through fine. However, the scrap on the left some how turned before reaching the anti-kickback teeth, and Whamm!! again.. This time the

4"X6" block nailed me a couple of inches below the belly button. Damn that hurt.

Now I have a healthy respect (fear) of the table saw. I thought this was suppose to be fun?

Gary

[Upscale]

Well, you've already given yourself the answer to what you should have done with the second piece. It's always advisable to use the mitre for pieces of wood that are not any bigger than the diameter of the saw blade. That's asking for it to twist in place and go flying as you found out. Hopefully, you're not in anymore pain and you've got some knowledge that has a good chance of preventing you from experiencing more of the same.

[John, in MN]

[snip] You may want to check out Charlie B's site:

reading on kickback, why it happens and how to prevent it.

-- John, in Minnesota

[Phisherman]

Years ago I was cutting some 1/4" ply, perhaps a 4x4-foot square. The saw kicked back the ply and made a black-and-blue mark on my thigh. Lucky for me (and you) it missed the family jewels. Now, I stop and think to myself, "Is there a safer way to complete this cut?" before reaching for the ON button. A clear-thinking head is so important.

[Leon]

If your fence is not parallel to the blade or the edge of the panel against the fence is not straight this can happen. In addition I always hold the keeper piece down with my hands. I have prevented several kickbacks by holding the panel down and letting the blade chew into the panel.

I read that your waste piece flew back. For kick back to happen the wood has to be held in place as it is struck by the blade. It must "bind" if you will. It takes very little resistance to cause a bind. Quite possibly the waste piece became bound by the guard and the guard held it in place as the blade grabbed it.

[Gary]

Exactly. I was concentrating on the piece to the right, being squeezed between the blade and fence. I may have pushed from both sides; push stick on the right, hand on the left. I just recall seeing the piece's back corner next to the blade twist in, in between the blade and splitter, and the come flying at me faster than the "Big Unit's" fastball.

[Edwin Pawlowski]

What am I missing? In this case the 4 x 6 cutoff was on the left of the blade and loose. If you used the miter, wouldn't that just shift the scrap to the right of the blade? Or did you mean the miter saw? (assuming you have one) Ed

[charlie b]

snip

On the 1/4" luan ply cut, were you basically making a rip cut or a cross cut, that is to say, was the long edge on the fence or the short end? If you were basically doing a cross cut, the four foot lever arm could have been a contributing factor - it's hard to get two hands that aren't touching each other to work synchronously. Doesn't take much different in feed rate between hands to cause the edge that's supposed to be firm against the fence to have one end come off the fence.

Another factor may have been the luan. Thin luan sheets have a tendency to curl or cup, requiring something to keep the piece ON BOTH SIDES OF THE CUT down on the table top. If either sideof the cut comes up off the table it can make contact with the teeth at the back of the blade - the ones that "kick off" kickbacks. Most of us know better than to rip a cupped or twisted board but don't seem to worry about cupped ply.

charlie b

[George]

You HAVE to look at the fence, and keep the wood against the fence as it enters the blade. Problem at start is you look at the start of the fence, not where the cut is starting. Same problem comes near the end when you forget that it's the piece between blade and fence that is advanced, while the other side follows.

I can almost hear Norm now. He says it every time.

[Leon]

Do not push from both sides as the cut is nearing completion. Let the waste side go where it will. Your only concern is to keep the confined piece of wood between the fence and the blade going in a straight line and not binding.

[Rich]

I had a nice kickback i posted a month or so ago. I push the right side though and left hand gingerly helps push piece through. I usually move my left hand in more as I move through the cut to keep from binding on the blade. You might of pushed with the left hand causing the piece to close the gap.

Anyway FWIW I hate cutting sheet material on the TS and I dont "crosscut" without a sled.

Rich

[Swingman]

You see a pattern here?

It I had to guess, and I do, it sounds to me as if you've gotten gun-shy, and by standing well to the LEFT, are not taking control of the piece against the fence, thereby allowing a situation to develop that can result in a kick back.

You've got be firmly in control around a table saw of that size.

If you take care to firmly control the piece between the fence and blade (i.e., keep constant edge contact with the fence and a firm grip on the piece), with a well tuned saw you will drastically cut your chances of an uncontrollable kickback happening.

Just my FWIW tuppence ...

[Leon]

Keep your left hand away from the wood as the cut comes within 3 or 4 inches of completion. You do not need the distraction of looking at where both of you hands are at. If you don't have the room on the right side for your hand, make a push stick that will also push down on the top of the work. My push stick comes in contact with the wood for about 8" on the top side and

1/4" on the back side.

[Elwood Dowd]

Does anyone else use homemade featherboards and pull the last foot through? I find that not only do the boards eliminate any premature kickback, I simply feel a lot better pulling from the other side. Particularly with long thin stock.

I haven't noticed any real accuracy errors resulting from this, though it is possible there are some. But then my saw is a $99 contractor's special, so my criteria for excellence are bit less extreme than some.

I discovered this after an "episode" that I still have a thin scar from.

[Swingman]

Color me cautious, but I've always been more than a bit reluctant to let go of a board mid cut to walk to the other side of a Unisaw and start pulling. :)

[Liam]

You can avoid kickback altogether for cutting 4" x 6" pieces... That machine sitting in the corner with the sawdust all over it is called a bandsaw... LOL

[POP_Server=pop.clara.net]

"Gary" wrote> Exactly. I was concentrating on the piece to the right, being squeezed

I think this emphasises the difference between a splitter and a riving knife. The latter is shaped to follow the curvature of the blade and can be fitted so that it is very close to the uprunning teeth.

Of course there is always a risk of closing a kerf onto the plate of the saw until the forward end reaches the riving knife.

The push stick needs to be applied as near in line with the saw blade as possible, this greatly reduces the tendency for the workpiece to turn, although this is more difficult if people follow the (unnecessary?) advice to stand well to the left.

Apart from very heavy pieces, is there any need for pressure from the left hand?

More on Circular Sawbench Safety on my web site.

Jeff G

[Upscale]

My mistake. I misread his description and thought the 4x6 piece was in between the blade and the fence.

I've never heard of a loose piece like that to the left of the blade go flying, but I suppose it's possible. Not sure how to handle something like that.

[J T]

Mon, Aug 2, 2004, 12:39pm [e-mail] (Gary) says: This weekend wasn't a good one First cut, an approximately 2'X4' cut off the end. Whamm!

I've been pondering your tale, since I first read it. I've cut plywood like that plenty of times, even as little as 2" X 48", with no problems. So, I'm not sure what you did. Maybe angled it a bit. I always make very sure it is firm against the fence. The largest I've ever cut tho, was 4'X4', that's as large as I thinkg I can safely handle by myself. I'm thinking you should have used a circular saw, and a straight-edge. I do that a lot, rather than use my saw.

Sunday morning, gluing up the drawers, I needed a 4"X6" block of 3/4 ply. Guard in place, I attempted to cut the piece off a 12" piece of scrap.

Done that plenty of times too, with no prob. However, I also usually just stuff that size on the scrollsaw, unless I need an absolutely straight cut. Maybe the bandsaw, but prefer the scrollsaw. However, when I do use the tablesaw, on a piece near that size, I use two pushsticks, not one. I keep my fingers well away from the whirly part. I "have" had cut pieces floating on the table top, but never had any kick back, because I use a push stick to flick it off the top.

JOAT The highway of fear is the road to defeat.

- Bazooka Joe JERUSALEM RIDGE

[Charlie Self]

Swingman responds:

I'm with you. I saw one person pulling a board through one time. It kicked back, and cut the daylights out of about three fingers for him as it was jerked out of his hands.

No thanks.

Charlie Self "Give me golf clubs, fresh air and a beautiful partner, and you can keep the clubs and the fresh air." Jack Benny