8/4 walnut pinching and curving?

[Jason Carlin]

I would have guessed that stock that thick wouldn't move much mid-cut, but this 8/4 walnut seems to be pinching the blade and my cuts aren't coming out straight. I'm a novice woodworker and this is my first time with 8/4 stock, so I really don't know what I'm doing. I did my best to align the fence and blade to one another and the miter slot on my Sawstop Jobsite saw, so I hope that's not the problem.

Any advice?

[Matt Day]

There was just a thread about reactionary wood a couple days ago. Likely your TS is just fine, but the wood wasn’t dried properly or has some internal stresses that you’re relieving when cutting.

Rough cutting with the bandsaw is a workaround.

Your Sawstop has a roving knife right? That should help. Give it some wax might help.

[robert wiggins]

I ripped walnut from a rough sawed 2x12 that had been air dried for years and was the correct moisture content. The pieces were to be turned for twin bed headboards. Two of the four ripped warped so bad they couldn't be mounted on the lathe. Wood stove material. I'm betten your saw is fine.

[Jason Carlin]

Yeah I've got a riving knife thank goodness. Honestly the possible binding is much less of a concern than the wacky curvy lines I'm getting. At least I'm fairly confident the riving knife will prevent the worst as far as kickback is concerned.

[Jason Carlin]

Ugh. That sucks. I really thought stock this thick would be more stable. I think I'm gonna have to cut it super proud of the line and then use a router with templating and flush trim bits to straighten the cut. That's what I did with the last one. Took forever. I'm just not comfortable trying to build and use a 60-something-inch sled for the table saw to straighten those cuts.

[scott vroom]

With a riving knife how is it possible for the wood to pinch the blade? Or did you mean to say that the wood is pinching the riving knife?

If the wood is pinching the riving knife, turn off the blade, back out the stock, turn on the blade and begin feeding again. This will create a new kerf on the pinch side of the stock. If it get's tight again, repeat until you're relieved enough stress to complete the cut.

[Andrew Seemann]

As a rule, thicker stock will be less stable than thinner stock when milled down in size, especially if you live in an area with a large difference in seasonal humidity (like me). The thicker the stock, the more out of sync the center will be with the current humidity and the more internal tension the wood will have. In an ideal world, your wood would be dried to just a little larger than final dimension, with only some surface flattening immediately prior to use. We all know that is a fantasyland though:)

If you can cut to rough length prior to rough ripping that will help some. You'll also probably have to oversize the pieces more than you normally want to, to accommodate the warp you get.

[Jim Becker]

As a rule, thicker stock will be less stable than thinner stock when milled down in size, especially if you live in an area with a large difference in seasonal humidity (like me). The thicker the stock, the more out of sync the center will be with the current humidity and the more internal tension the wood will have. In an ideal world, your wood would be dried to just a little larger than final dimension, with only some surface flattening immediately prior to use. We all know that is a fantasyland though:)

If you can cut to rough length prior to rough ripping that will help some. You'll also probably have to oversize the pieces more than you normally want to, to accommodate the warp you get.

This.........................

While buying thicker stock and sawing it down into thinner/narrower pieces sometimes makes sense, it raises the risk for movement from both moisture and tension release. Thicker stock also has more challenges with moisture equilibrium between the surface and the center of the material.

[Kevin Jenness]

Some lumber is well behaved and some not. Most often squirrely behavior is related to poor drying and uneven moisture distribution within the work piece but inherent stress from leaning trees and juvenile wood can factor in too. The best approach is to be conservative, block out the rough lumber wider and longer than finish dimension and let it sit before further milling. As Matt said, a bandsaw will be safer than a tablesaw for the initial cuts.

Sometimes a piece will bind so badly on a tablesaw that driving a wedge into the kerf is the only way to free it up. If you are only removing a small amount from a roughed-out piece that won't happen.

[Jason Carlin]

What can I do to straighten it after the fact? I have a 2x2x60” that bows more than 3/16 over its length. I don’t have a jointer and my job site saw and a sled sounds dangerous.

[Alex Zeller]

About 10 years ago I bought a bunch of 8/4 rough cut cherry that wasn't kiln dried correctly (case hardened). It was warped and had a few checks. It was cheap and I had a project that only needed short pieces. I ended up putting them up in the rafters waiting for the project to get the go ahead (which never happened). I have used a few but the best I could do was just use the pointer and planner to flaten them. Lots of wood shavings later they were usable. I didn't feel comfortable using them for a project for a customer without knowing for sure they wouldn't twist or check but so it's been just stuff for me. I haven't had any problems with them. Without a jointer I'm not sure what I would do. Maybe mount a long straight board to the fence on your table saw and a hand jointer to take don the high spots? I think the safest option would be to have someone with the proper equipment straighten them.

[scott vroom]

What can I do to straighten it after the fact? I have a 2x2x60” that bows more than 3/16 over its length. I don’t have a jointer and my job site saw and a sled sounds dangerous.

It would be helpful if you could provide a description of your project and where the 2x2x60 piece fits in.

[Jacob Reverb]

What can I do to straighten it after the fact? I have a 2x2x60” that bows more than 3/16 over its length. I don’t have a jointer and my job site saw and a sled sounds dangerous.

In general, you're better off cutting to length before cutting to size, because straightening a shorter board requires you to remove less material than a longer board.

For example, you might need to remove 1/4" from each end of a 60" board to get the edge straight/jointed, but if you cut it in half first, to two 30" pieces, you might only need to remove 1/8" from each end to get them straight/jointed.

Also, you don't necessarily need a jointer to straighten a long board. Tack a straight piece of lauan to the concave edge to ride along the fence, then rip off the convex edge, then remove the lauan staightedge and rip off the concave edge...

[Kevin Jenness]

There are a number of ways to straighten out a crook with a tablesaw; Alex and Jacob have offered two. Before I got a sliding table saw I used a simple straight-line jig found in Tage Frid's first book. It consisted of a 9"x8' piece of 3/4" ply with a guide strip below to run in the miter gauge slot and a stop at the back end with a protruding screw tip to grab the workpiece which was held to the jig by hand. Narrow pieces would be best held with toggle clamps.

If you do much cabinet or furniture work you will find a jointer very useful. There are workarounds but there is a reason that one will be found in any commercial shop using solid wood.

Another approach is to use a router and a straightedge clamped to the workpiece.

[Tony Zaffuto]

If reactionary wood or case hardened, it may never quit moving.

Years ago I got a terrific price on clear cherry, albeit nothing much longer than 5' long and 6" wide. Young, dumb and foolish I was to not know what I was getting. Fast forward to about a decade ago, I bought some walnut-8' to 10' lengths and 8" to 10" in width, and same thing as the OP happened to me. Figured it was not dried correctly.

Best cure? Find a lumber dealer you can trust to deliver honest value. For me, it is Grof Lumber from Quarreyville, PA.

[Andrew Seemann]

What can I do to straighten it after the fact? I have a 2x2x60” that bows more than 3/16 over its length. I don’t have a jointer and my job site saw and a sled sounds dangerous.
Well, you could always take a jack plane to it. I have a crummy jointer, and for long pieces sometimes have to mark a straight line on the board and plane to the line. I use that against the fence, so I don't need to worry if I planed the edge exactly square. I use that edge as the jointed side and then rip to width. If you have enough length or width, using the "screw a straight board to it" and other methods mentioned above work well too.

Another option, depending on how ornery the wood is, is to find some other walnut that is better behaved. For every species of wood I have used, I have run across at least one board (sometimes much more; I'm talking about you Birch, Beech, and Sugar Maple, and don't look so innocent, Elm) that refuses to submit to cabinet making. Often it is the prettiest boards, because sometimes what makes a board pretty can also make it unstable. They look pretty in the fire also:)