FWIW Kickback

[Rich]

Cross cutting a 13 x 30 piece of 3/4 ply. I had thought that it was a little narrow to cross cut BUT pushing aside that one shred of common sense I cut it anyway. This ply is very light weight for 3/4 (luan) so I am thinking this was part of the problem. Anyway I turned the right side piece just a hair as I was just finishing the cut. Probably now that it was free it needed less force to guide accross the saw.

The blade grabbed it, spun it around on the top of the saw like a top and shot it out and hit me in the gut with more than a little force.

Having a nice red line across my mid section about 3/4 thick is very interesting. Not to mention the pain inside when eating and drinking. I would attribute the same feeling as if someone took a broom handle and did a Sammy Sosa to your stomach. This was Friday at noon and the pain is more localized to the 3/4" stripe now.

There are no exterior bruises or serious internal damage so far and no flesh touched the blade, thank God, this incident could of been so much worse.

Stats: TS with no guard or splitter Rushing project

I will finally make my crosscut sled now as I have been warned.

Rich

[bridger]

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having your saw punch you in the gut is a real eye opener, eh?

cheap lesson.

make that sled today..... and the zero clearance insert with the splitter in it....

[Leon]

You know that "Gut Feeling" you have some times... Let it be your guide so that the "GUT" feeling that you have now will not be common place. ;~)

I am glad to hear that you are still with us..

This cut can be safely made, but you absolutely have to keep the panel flat against the fence through the WHOLE CUT and the edge against the fence has to be absolutely straight. Your hands firmly pressed down on top of the panel as it is being cut will help hold it down in the event that the blade grabs the panel. If the edge against the fence is not straight, what happened to you is likely to happen over and over. As you indicated, a sled is a safer option.

[J T]

Sun, Jul 11, 2004, 2:08pm (EDT+4) [e-mail] (Rich) claims: Cross cutting a 13 x 30 piece of 3/4 ply. I had thought that it was a little narrow to cross cut

I do a lot of cross-cutting, usually about 12", or sliglyly less, wide. No prob. Of course, I do use a saw sled.

Making a success of the job at hand is the best step toward the kind you want.

- Bernard M. Baruch More likely, your boss gets a raise and/or promotion, from getting credit for your work.

- JOAT

[Wes]

horror story snipped | |Stats: |TS with no guard or splitter

There is your major problem. A splitter would have likely prevented this.

|Rushing project

A secondary, but contributory factor.

| |I will finally make my crosscut sled now as I have been warned.

Aha, a man who learns by his mistakes.

Boy have I done a lot of learning. [g].

Wes

[B a r r y]

For a crosscut? He was crosscutting a 13x30 piece ply.

I'm guessing he was either using the fence, thinking that 13" was enough to simulate a rip, or trying to freehand it.

In either case, the work can fly even with a splitter.

A splitter is not necessary with a properly done crosscut, as the sled or miter gauge prevents attempting to cut a curved kerf, and wood dosen't close up when cut across the grain like it does when ripped.

Barry

[Swingman]

It would be interesting to know if he had one installed. IME, there is distinct possibility that a splitter may well have prevented the incident. The OP stated he was at the end of the 13" cut and a splitter may have physically prevented the board from rotating onto the back of the blade, which was the mechanism that propelled it toward him.

A riving knife, of the European kind that hugs backside of the blade, may do a better job of it, however.

On that note, I did a tune-up on my Unisaw today ... first one in over a year. The fence was toed out at least a 1/32nd at the back, and was about 2 degrees off being perpendicular to the table wings. Although I haven't noticed a deterioration in cut precision, apparently I need to start checking these things more often to be on the safe side.

[Mark]

aYup, playing roulette.

But you see, it could never be a matter of extremely poor judgment.

[patriarch]

"Swingman" wrote in news: [e-mail]:

I did the same last month, 18 months after installation of the new Unisaw. Seems that bouncing the saw & mobile base over the expansion joint in the concrete ustabeagarage floor caused the horizontal alignment of the extension table to go out. That led to adjusting the wings & top, requiring the adjustment to parallel of the blade & miter slots, as well as the fence. Cleaned out the accumulation of various chunks, sawdust & debris from inside the saw as well.

I don't think I just imagined the improvement in the quality of the cuts.

Yesterday's maintenance chore was cleaning & emptying the dust collector bags and tubing. Next up: cleaning the crud off of the sawblades in the holder, and determining which are due for a touchup.

Patriarch

[Wes]

|On Sun, 11 Jul 2004 17:08:56 -0700, Wes wrote: | | |>|Stats: |>|TS with no guard or splitter |>

|>There is your major problem. A splitter would have likely prevented |>this. | | |For a crosscut? He was crosscutting a 13x30 piece ply.

Well, he said, "Anyway I turned the right side piece just a hair as I was just finishing the cut. Probably now that it was free it needed less force to guide accross the saw."

I imagined that he was using the 13" side against the fence, otherwise, I can't imagine "turning the right side piece...."

| |I'm guessing he was either using the fence, thinking that 13" was |enough to simulate a rip, or trying to freehand it.

That's funny, do we agree or not? Since as I just stated, that's exactly what I was thinking, which makes it a "rip cut" not a crosscut.

| |In either case, the work can fly even with a splitter.

Much less likely in the envisioned scenario, especially if the splitter incorporates (as mine does) anti-kickback pawls.

| |A splitter is not necessary with a properly done crosscut, as the sled |or miter gauge prevents attempting to cut a curved kerf, and wood |dosen't close up when cut across the grain like it does when ripped.

Yeah, but it's the "properly done" part that is the gotcha.

Wes

[George]

For the right side piece to turn, it would seem to me there was no fence involved, or he failed to use a cutoff stop to provide clearance and was guiding from the other side of the blade. If there was a standard miter gage in use, he must have been doing the unforgivable and holding on to the offcut, a recipe for disaster even on a 2" crosscut.

In any case, tilting the trailing edge of the piece into the blade could easily spin that puppy around and back. Whether or not a splitter would have helped depends on the height of the splitter and the lift imparted to the piece. A blade guard or good sense would have prevented the entire incident.

[B a r r y]

Not really. I wrote "simulate" a rip. He's not actually ripping, only fooling himself that he is. This is a very common newbie move with plywood.

One of these cuts WILL kickback with a splitter. When I was a green newbie, I did the same, with a splitter. The result was so painful that I actually thought I had just killed myself.

|

Not really. The short edge of a long strip of ply dosen't really hold well in the pawls once the part gets leverage against the fence. My incident also involved pawls. My pawls had a bit of side to side play, which easily allowed the ply to slip out from underneath as it rotated. The pawls work better on a real rip due to grain orientation and the overall length of the work.

Barry

[-linux_lad]

Better get started on that crosscut sled. I was ripping some warped

5/4 fir with no splitter when I heard a noise and turned my head to look over my left shoulder. At that moment, the saw grabbed the stock and flung it into my stomach sideways with enough force to knock the wind out of me. It left a nice rectangular bruise, and a served as a reminder of the awesome horsepower of a 3hp saw.

--

-linux_lad To verify that this post isn't forged, click here:

[George E. Cawthon]

in the face by a horse. Now that's only about 1/4 horsepower. Makes your whack in the stomach a stroll in the park.

[Rich]

The original piece was like 42-48 inches long by 13. I needed to cut it down

30". I set my fence at 30" and guided it through. Whenever I cut ply I always look at the gap to keep from binding on the blade. I usually adjust this by my left hand position, bringing it closer in to keep from binding. Well all my attention was on the left side and the gap and not noticing I turned the right piece slightly. I remember the blade cutting a curve in the ply right before all heck broke loose. I'm guessing I turned the piece slightly clockwise but I cant remember as it happened so fast.

Normally I have a guard and splitter on the saw but when I have to remove it for something it takes a long while before I get it back on. I'm thinking the guard and splitter would at least restricted the ply from dancing around like a top then shooting it out! But who knows, this saw has 5hp so maybe the guard would of bounced off me too. ouch.

Next time I have a judgement call I hope to make the not so stupid decision this time. Guard will go back on and cross cutt sled will be built.

Sincerely, Rich

[B a r r y]

Just as I thought.

BTDT, glad to hear you're not permanently damaged!

Barry

[Wes]

|On Sun, 11 Jul 2004 22:54:44 -0700, Wes wrote: | |>|I'm guessing he was either using the fence, thinking that 13" was |>|enough to simulate a rip, or trying to freehand it. |>

|>That's funny, do we agree or not? Since as I just stated, that's |>exactly what I was thinking, which makes it a "rip cut" not a |>crosscut. | |Not really. I wrote "simulate" a rip. He's not actually ripping, |only fooling himself that he is. This is a very common newbie move |with plywood.

Hmmm. My brother's name is Barry, so I feel like I'm arguing with him, which was never very productive either. [g]

If we are cutting ply that has no defined grain pattern, can we agree that neither rip nor crosscut have their regular meanings. In which case I propose that if the fence is in use to guide the work it is a "rip" cut and if a miter gauge or sled is in use it is a "crosscut."

I'm guessing (always a bad move) that you consider it a "rip" when the long edge of the workpiece is against the fence and a "crosscut" when the long edge of the work is against a miter gauge or sled.

If, on the off chance that I guessed correctly, how should I cut a two-foot square of plywood in half? Do I "rip" it or "crosscut" it? What if the piece is one-foot square? (My secret answer here)

Regards,

Wes

[Edwin Pawlowski]

OK, we all know a sled it best. I've done this sort of thing though, but have take a different approach. I set the fence (allowing for kerf or course) for the short dimension. In your case, it would have been about 18" to leave the 30" needed.

I don't look at the gap at all. I look at the wood against the fence while pushing VERY hard with two hands to keep it there. I push it completely past the blade and turn the saw off. After the blade stops I'll pick up the waste on the outfeed table and the good piece on the left extension.

I'm not advocating this method. A panel sled is the way to go. Ed

[B a r r y]

I'm not arguing, I'm discussing. Sorry you feel differently

RIGHT!

It dosen't matter, it's square. Read on...

What the OP did was try to cut a 40 something x 13 inch ply part down to 30 inches using the fence, rather than a proper miter gauge or sled. Maybe he was using both a gauge and the fence. Either way, a part that is much wider than it is long is very easy to launch this way. The part gets ever so turned, and since it's trapped between the fence and the blade, the blade gets all kinds of leverage to grab the board. On a normal crosscut without the fence, the board would simply turn, simply damaging the end of it. Since the fence IS there, a very memorable event follows,usually even with a splitter.

The true moral of this story is NEVER trap a board that is much wider than it is long between the fence and the blade. If using the fence to measure repeat cuts, use a short stop block clamped to the fence, so that there is nothing to trap the wood.

What the OP did could have just as easily have happened with a glued-up wide solid board, the fact that it's ply is actually irrelevant.

Barry

[Swingman]

That could be a dangerous piece of advice without a miter gauge, eh?