Ripping woes

[ts]

I've been woodworking for quite a while (20+years) and must be getting dumber. This sounds crazy but it's real and I'd like some useful advice on causes and cures.

Lately when I rip I end up with the good piece having a concave edge on both solid and plywood. The curve is noticable when it's laid on edge on the table saw table. I've tried with and without a feather board and splitter. The fence is square to the miter slot (as best as i can tell with an adjustable square) and the blade seems to be also - using the same method. What I've noticed is that the board creeps away from the fence after it is cut. I've tried putting pressure on the board so it's up against the fence as it enters the blade. Nothing I've tried seems to help. The curve is noticable on ~2' pieces and larger. I don't remember having this problem earlier in my woodworking hobby. What do I need to start /stop doing -- hints? Thx.

[none]

I'd confirm that the square is really square. Even the slightest outage on the square will magnify on a blade and even more so on a fence.

[none]

I'd also add that situations like these are where you really want to have a decent fixed square on hand. Worth every penny when you want something to be accurate.

[godsword]

I do not know anything, but if it happened to me, I would change the blade. I believe that the blade is more dull on one side than it is on the other, causing a twist in the blade as you cut.

[Lew Hodgett]

---------------------------------------------------------------------- Sounds like a set up problem to me.

If you are working alone is work piece fully supported by runout table(s) during cut?

The following assumes that trunnion provides a parallel blade mounting surface to miter slot.

1- Make sure your blade is parallel to miter slot on T/S. 2- Make sure your fence is parallel to miter slot on T/S. 3- Make sure your blade is perpendicular to the table. 4- Make sure the splitter is working properly and INSTALLED.

All these tests can be performed using an inexpensive dial indicator and some home made jigs.

Good luck and have fun.

Lew

[Leon]

;~) Well hopefully your fence is not square to the slot, it should be parallel. But that is probably what you meant.

What condition is your saw in? Could worn bearings be a possibility.

Secondly you mention that the edge is concave, is that bowed along its length or is the middle of the cut deeper than the top and bottom sides of the material?

Are you using a think kerf blade? If it is a very likely culprit especially if it is not sharp.

Are you buying quality lumber? Case hardened wood will bow after being cut although this does not explain the problem with plywood.

My first guess is that you are using a think kerf blade and that is giving you problems.

What I've noticed is that the board creeps away from the fence

[Larry W]

Sounds like your blade is just slightly out of parallel with the fence when ripping. Think about cutting a cove on the tables saw and you can visualize how the edge becomes slightly concave.

[Keith Nuttle]

I thought I knew a little about saws but then saw your reference to a "think kerf blade" What is it.

[Bill]

Roughly speaking, "kerf" refers to the thickness of the saw blade. One may be able to cut faster with a "thin kerf" blade or make due with a less powerful saw by using thin kerf blades. They are, of course, more flexible. Based on my very limited experience, this is a big negative, and I'm not planning to purchase any more thin kerf blades unless the application calls for it (cutting veneer or similar).

Bill

[clare]

The stress is coming out of the wood when you cut it. Not sure what you can do to prevent it. I generally cut oversize and then run it through the jointer/planer to true it up when I run into the problem on a batch of lumber.

[Puckdropper]

Bill wrote in news: [e-mail]:

That's a "thin kerf blade", but what is a "think kerf blade"? ;-)

Puckdropper

[Morgans]

No square is accurate enough, imho. Use a very straight sharp edged straight edge at least the width of the saw hold it against a and a blade with absolutely no wobble. Thousandths count. Take a steel rule with

64thson it and adjust the table with the miter slot and straightedge to within half a 64th. Once done, this adjustment should hold for a very long time. Now, line up the rip fence to the miter slot. Make sure it is straight and NOT SLIPPING. Set the darn measuring pointer gauge while you are at it! ;-)

jim in nc

[Lew Hodgett]

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1/8" is standard for a 10" dia blade last time I checked.

Lew

[Bill]

Everyone's a comedian!

[phorbin]

I thought it was a pretty good typo.

[dadiOH]

The fence isn't square to the blade, back end of the fence is farther away.

Try cutting a board and clamping the offcut to the table without moving it. Lower the blade, move the fence to the offcut's edge and adjust it to be parallel with the offcut.

[dadiOH]

He said it happens with plywood too.

[Keith Nuttle]

Combined with the Parallel square problem, so did I.

There were so many serious answers to my questions, I think I understand how these discussion can go on forever. People are answering what they think was written not what was written.

[Leon]

Thin about it a little while.

[tom]

Make sure the blade is parallel to the fence rather than the slot by measuring the leading edge of the blade and the trailing edge in relation to the fence.