Ripping imperfect wood on a tablesaw.

[Tom Bender]

Some wood has stress that makes the kerf close and pinch the blade or open and push against the blade (it doesn't take a lot of pressure to flex a riving knife). What to do?

Get different wood, Sure, we're all going to do that....

Rip on a band saw, safer but the problem is similar

Install a half fence that goes just past the blade

Don't cut all the way thru and finish with a hand saw

Other?

[John K Jordan]

Some wood has stress that makes the kerf close and pinch the blade or open and push against the blade (it doesn't take a lot of pressure to flex a riving knife). What to do?

Get different wood, Sure, we're all going to do that....

Rip on a band saw, safer but the problem is similar

Install a half fence that goes just past the blade

Don't cut all the way thru and finish with a hand saw

Other?

I'd rip a bit on the bandsaw (no kickback potential!) then push a little wedge in the kerf to keep it open. This has worked for me.

[Lee Schierer]

If you have a helper you can have them insert wooden wedges in the out feed side of the cut. Cabinet leveling shims work well for this. Don't try to do this if you are alone. Keep in mind that the wood may continue to move as it is processed into your project.

[Jacob Reverb]

If the kerf is closing on the blade, I will sometimes stop halfway through the cut, turn off the saw, then cut from the other end of the board while holding the kerf open with my feed hand.

[Mark e Kessler]

I knock a wedge or a screwdriver in it and march on...

[Mike Cutler]

Tom

I am 6'3" and have chimp arms, so this might not work for you, but here goes;
I keep a couple of those plastic toilet leveling wedges on the fence. If the kerf gap, starts to close, I just kind of pause and stick a plastic wedge in the kerf. My height and arm length make it so I am no where near the blade when I do this. A shorter person might have trouble with my solution.
These plastic wedges are about 2" long and about 1-1/4" wide, kind of have a texture to them for friction. They sell them in the plumbing section of Home Depot, or lowes. I like that they're plastic.

[Steve Rozmiarek]

Don't rip full to finish width in one pass, if you are making a 8" wide board into a 6" for example, do one rip at 7 and a finish one at 6.

[Pete Staehling]

Depends on how bad it is. If bad enough, strike a line on it and cut by eye on band saw with no fence to approximate size. Edge joint one side and rip to finish size.

Oh and cut to approximate length first. That often is enough by itself.

[Paul F Franklin]

The half fence may help if the kerf tends to open, doesn't help if the kerf wants to close. And with a half fence you have very little support of the stock for the last foot or so. Don't see that as a good solution for ripping.

Another option that hasn't been mentioned is a track saw. Saw a bit and if the kerf is closing it's easy enough to stop and wedge it. Or, if you know the stock is wonky, you can start with a plunge cut a few inches from the end so the uncut portion remains to hold the kerf open. Then go back and finish the cut with the track saw or a hand saw.

[Erik Loza]

Subscribed: I've had this happen a bunch of times on the slider. You can feel the wood starting to move as the cut relieves the stress. Kinda' scary on a 10hp saw. The toilet wedges are a great idea.

Erik

[Bill Dufour]

Any wedges should be wood or plastic in case they go into the blade.
Bill D

[Patrick Kane]

Is it closing up so badly on your riving knife/splitter that you cant continue to feed it? Do you have a riving knife or splitter installed?

Option A for me always involves forcing it through the cut. As long as you are firmly in control, the board wont kickback. If you are timidly expecting the kickback, then that is when you are going to take a board to the gut.
Option B usually occurs after ive stalled the saw. Yes, ive done this a few times on a 5hp saw, many times on a 3hp saw, and a lot on a 1.5hp saw. Sometimes it will be clamped so tightly on the blade/riving knife after the stall that i need to pound open the kerf with a chisel before restarting the saw. Keeping wedges nearby is a good idea, but i would prefer to insert them with the saw off.

[Tom M King]

If I feel one closing up on the blade, I lift the tail end that I'm holding if there is enough of the board past the blade to help lever it up, or push down on the board tilting it on the front of the saw table, whichever is required to clear the board from the blade, and start the cut over-as many times as necessary. I'm sure this requires some feel from experience, but I've never had one lock up the saw, or kick back on me. This with 45 years pro experience, and I don't know how much before that. I've never used a table saw with any kind of safety device on it, because some don't allow you to use my method-not saying to try this at home. I wouldn't consider applying more force.

[David Eisenhauer]

Adding wedges to a pinching cut has always sounded better than it actually works for me sometimes. Kind of need three hands at times. For me, the best control of the operation is to rip at less than half the thickness of the material from each side and then saw the remaining quarter inch or less with a hand saw. I don't worry excessively about kickback (I am positioned out of the way), but do worry about pinching a blade, jamming the wood onto a blade, stalling the motor, etc. I ruined a decent BS blade once with problematic material. Again, for me, it is worth taking the time to do the rip in three steps if it at first looks like there is going to be problems.

[justin sherriff]

I have when it starts to pinch the riving knife I turn the saw off pull the wood off and then start the cut again. It widens up the saw kerf on a bad peace I have had to do it more than once.
Not sure it is the rite thing to but it can work.

[Mike Cutler]

Subscribed: I've had this happen a bunch of times on the slider. You can feel the wood starting to move as the cut relieves the stress. Kinda' scary on a 10hp saw. The toilet wedges are a great idea.

Erik

Erik
Yep, they do work well. Cheap too.
Like i said though, I'm tall and have long arms, so it works for me.
I also use feather boards pretty much all the time, so my left hand is always able to grab one once I see it happen. Sometimes I'll just put one in any way.

Don't anyone believe it can't happen on a band saw. It definitely can.

[johnny means]

I always back out the cut when I start feeling the pinch. I then just push the board back on through.

[Edward Dyas]

Some wood has stress that makes the kerf close and pinch the blade or open and push against the blade (it doesn't take a lot of pressure to flex a riving knife). What to do?

Get different wood, Sure, we're all going to do that....

Rip on a band saw, safer but the problem is similar

Install a half fence that goes just past the blade

Don't cut all the way thru and finish with a hand saw

Other?Some wood just does that. I've found it's best to discard wood like that or use it for very small parts.