Ts cutting situation

[richard b miller]

i've got the grizzly 0715P table saw. it has enough power for all i need (so far).
i ran into a situation this morning ripping some pine 2x10x48"s. i was cutting it in 3" strips for a table top.

i started cutting it and approx. 4" in, it jammed the blade. i flipped it over long ways and tried from the other
end and it jammed again. i flipped it cross grain and tried again. it jammed up the blade again.

i had already cut two other 4 footers and one of them was the other half of this board (original 10' board.)

i checked moisture content and it was 15%. the other pieces were 12%-15%.

any ideas what would cause it to jam? and why only that half?

thanks all
rich

[Nick Shattuck]

Does it jam immediately (like it's hitting something incredibly hard)? Or does it slowly spin down (like it's getting pinched)?

[Phillip Mitchell]

Jammed as in pinching the table saw blade?

15% MC isn't quite what I would call dry, but close in summer in the South.

The wood is likely releasing stresses as you rip it and pinching the blade in some way from the movement. It could either be the kerf closing up and pinching the blade or the "keeper" piece of your rip cut is moving during the cut and pinching between the fence and blade.

Is this pine from a big box store or lumberyard? This stuff is rarely dry, and the lumber isn't from decent logs to begin with. I've found this causes a lot of little issues like this during cutting and dimensioning.

[Bill Dufour]

Is you splitter as wide as the blade you are using? Sometimes I even stop the cut half way and jam a nail or screw into the kerf to keep it open. i really should plane some scrap wood a little thicker then the saw kerf to use.
Bill

[Lee Schierer]

i really should plane some scrap wood a little thicker then the saw kerf to use. Bill

This is what I have done. I don't like having steel in the kerf behind a moving blade.

[Wayne Lomman]

It is most likely stress relief in the timber. Drive a wooden wedge in the saw cut as it clears the back of the riving knife keeps the required clearances. 15% is quite high for furniture. 8% in a dry climate and 10% in the subtropics is our standard. If you have time, rip the timber and sticker it for a couple of weeks before continuing. Cheers

[glenn bradley]

Still not clear whether we are getting sideways pressure or pinching at the blade. Tablesaws cut straight. Are the edges against the fence and the surface against the table milled true? The other half may have been close enough to straight to make it through the cut. since you changed reference edges I am not sure without a little more info.

[richard b miller]

to try answer the questions.
1. it slows down as i start into the wood. ie pinching the blade2
2. width between my riving knife and the blade is .020, knife being thinner
3.the fence and blade are square and true. i'm certain of that.
4. as for the wood itself, yes its from a box store. HD, not lowes (lowes has crappy wood). but i'm not sure
getting wood from my local sawyer would have made any difference.

i'm going to wedge the kerf to see if that works. will let you all know.
thanks

[Mark Wooden]

How high is your blade in the cut?- more than 1/4"-1/2" above can cause heat which can make the pine move and pinch if damp.

If you can remove the riving knife easily-
Drop your blade to a little more than half the thickness of the stock, rip, flip it over and then cut through. This will get the piece cut safely as you will relieve a lot of stress with the first clearance cut.

The small wedge after the riving knife works well also, be careful while doing it as the wood can move while the blade is running. Be ready for the piece to "pop" open also, there can be kickback when it happens.
When ever I have to deal with ripping questionable stock, I cut large and use a full kerf rip blade that cuts several thousandths clearance from the saw plate. Then joint and size the stock

[andy bessette]

Use a quality carbide rip blade.

[Peter Christensen]

First off my I suggest clamping a board to your fence that stops just past the teeth of your blade. Effectively making a half fence like the Europeans use. It stops binding between the blade and the fence if the wood bows the other way.

Secondly raise the blade to maximum height if you have a splitter and guard with anti kickback pawls. The reason is fewer teeth are cutting at any moment in time thus using less power.

I'm not clear from your original post if the blade binds 4" from the front of the blade or 4" past the back of the blade. From the front you have wood with serious internal stress that may not yield any useful pieces. From the back you can push wood wedges as you go but it's better to get a second person to do it so you can maintain control over the wood you're cutting.

If you think the pine is bad you should see what maple does when it has natural and drying stress in it. Spiraling and corkscrewing to say the least. ;)

[Rick Potter]

Try the cut again. When it gets tight, stop the saw. Lower the blade with the wood still on the saw. If it is pinching the riving knife, it's tension. Pretty common problem.

I ran into a lot of it with red oak recently. Worst stack of lumber I have had in years. I use a plastic construction shim from the borg. If you have to do a few cuts, it is nice to have a helper insert the shim as you go. I have had wood actually split the last few inches before it got to the blade. Putting on the short aux. fence is good advice also.

Cut the wood wider than you need, it will need jointing after sitting a day or two.

[richard b miller]

i placed this board indoors for a few days and this is what happened! i did finally cut the board in 3" strips
and every piece had a warp and twist! i cut it by running it thru my ts cutting 1/4" each time. the first
piece actually split before i got to the end, like Rick said. i would up throwing the pieces on my burn pile!

thanks all
rich365284

[Steve Peterson]

There is a lot of tension in that piece of wood to force the cut closed in such a short distance.

The outside edges probably dried too fast, but kept from shrinking because the inside still had lots of moisture. Then the inside dried and wanted to shrink. This causes a lot of stress in the wood that gets released when cut. You end up with banana shaped wood.

Not sure anyone mentioned it, but you might have been able to rip the wood on a bandsaw. It is hard for a 1/4" or 1/2" blade to get pinched. You still end up with bananas. Some wood just can't be saved.

Steve

[lowell holmes]

I would try to make the same cut on a different board and see if it happens. It might be the wood you were cutting.

[Charles Lent]

I have had this problem. One 4' long piece exploded and flew off the saw when I was almost half way through the cut. I took it back to the lumber yard and they gave me another piece, along with an apology. Wood that is properly and evenly dried does not do this. Incorrect drying conditions frequently cause high stress in the wood. It will be most common in construction grade lumber, but can happen in any lumber that is dried too quickly and unevenly. Long rip cuts is when you will most frequently experience this. Having a splitter or riving knife on your saw should help prevent injury when this happens, and it's usually best to quit and use another piece of wood, because it will continue to react, warp, and twist, making it totally unusable anyway. Whenever cutting solid wood stock for projects I always cut each piece slightly oversize, then come back in a day or to and trim them to their final sizes. This gives them a chance to equalize and the slight trimming to final size gives me a chance to straighten and correct any warping that has occurred. They don't move much after this final trimming to size because so little additional wood is removed. Again, construction grade material is where you will have most of these problems, and it's mostly caused by rapid and incorrect (uneven) drying.

Charley