TS tearout on blade exit?

[Dukester]

I call it tearout for lack of a better term. Whenever I make a rip cut on my TS with the blade 90 degrees to the TS top, as the board exits the rear of the blade there is a large (maybe 1/16") tearout on the rearmost portion of the board (that portion of the board that exits the blade last) as if the blade were tilted slightly left. Looking at the board from the rear end grain would look thusly:

------

------ \-----

The first 99% of the stock is dead on 90 degrees to the adjacent face. It's just the last 1/4" or so.

As a test, I found that if I stop the saw before the stock exits the blade but after the cut is completed, there is no tearout (I only tried this a couple of times). It's consistent enough that I have trained myself to rip larger than necessary and make jointer passes until the damaged end is removed. I have used featherboards to keep the stock up against the fence, and aligned and realigned the blade. It only occurs in the very rearmost portion of the board, about the last 1/4". It does not occur when making a dado type cut with the same blade through the center of a board, i.e. a kerf down the center.

What's the deal with this?

--Cheers! Dukester

[Leon]

Do you also get a Zing sound as the board clears the blade?

I could be technique, a board that is not straight, a bad blade, or your TS needs a serious tune up to align the blade to the miter slot and the fence to the miter slot.

[Doug Miller]

On this basis, and because this apparently happens *all* the time, and because you mention below that you have a jointer and you appear to know what it's for, we can presumably rule out twisted stock as a cause. :-)

That suggests that the table isn't flat, at some point past the leading edge of the blade. The very first thing I'd check in that regard is the throat plate. It's not a bit unusual for the plate to not be perfectly even with the table top, and that can allow the stock to shift, causing problems such as you describe.

Have you checked the alignment of the fence and splitter, to make sure that they are *also* square to the table? Sideways pressure from the featherboard might be enough to twist the stock against a cockeyed fence.

Yep. Board's supported on *both* sides of the blade, instead of only one.

Probably an uneven throat plate. Lay a straightedge across the plate at the front, middle, and rear, and along the plate front to back as well, and I'll bet you see some places where it's uneven. Specifically, I bet it's low on the side toward the fence, and more so in front than in back.

Tweak the height-adjusting screws as needed, if it has them; otherwise, shim or file as needed until the plate is dead even with the table all the way around.

While you have the straightedge out, check the table, too, to make sure it's flat. If you're using an auxiliary outfeed table, make sure it's dead even with the saw table, too. Irregularities in both of those areas could also cause this problem.

You should also check to make sure your splitter and fence are dead square to the table.

But I think it's most likely to be the throat plate.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[bluemax1811-newsgroups]

Do you get the same problem if you cut without featherboards?

Bob

[Dukester]

Yes. Identical.

[Dukester]

Seems like it "zings" as it exits. I'll check tonight. What does the "zing" signify?

[Leon]

That you have accurately described the problem, When the blade becomes loaded from the side vs. straight on, it will typically make that sound as it exits the wood.

[bridger]

try a better blade.

[Dukester]

Doug, the throat plate adjustment hit it right on the nail. Sure enough it was out of keel at the back of the plate. Adjusting it made a square cut on the first try (and the 2nd, 3rd, 4th,...).

Cheers! Dukester

[Doug Miller]

Thanks for the followup. Glad to help.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[Highland Pairos]

Thanks for posting the follow up. I was lurking curiously and hoped to hear what the cause was.

Steve P.