4/4 Maple: Jointed/Planed all straight. Resawed now warped????

[Jason Saiki]

Hi all,

This weekend was my first attempt at resawing on my tablesaw (I don't own a BS). I first jointed and planed 2 boards, 1 hard maple and 1 red oak (5"x13" maple, 5"x24" oak). I was very happy with how straight each one was. Both woods were sitting in my shop for over 6 months (the oak was actually cut years ago).

Now, I tried to resaw each to 3/8 using my TS (Ridgid TS3650 with Incra TS/LS), using stacked featherboards to keep them aligned. I didn't cut all the way through: I left about 1/4" in the middle and used a hand saw to finish.

When I got both boards split, I placed the jointed face to ensure it was still straight and now it's warped. I didn't measure but it must be off by 1/32". I tried the oak first and I thought that perhaps I released some tension but the maple (which I thought was really stable) had the same thing.

Any of you guys have any thoughts what I did wrong?

Mahalo from Hawaii

[David Hostetler]

The first thing that leaps to mind is moisture content. Is your lumber thoroughly kiln dried and acclimated to your shop?

[Jason Saiki]

Thanks for your reply David. I don't know if it was kiln dried but both boards were sitting in my shop > 6 months. In the case of the oak, it was sitting in my brother in laws school (w/o air conditioning) for years. Our humidity is always around pretty high.

[Kent A Bathurst]

Hi all,

When I got both boards split, I placed the jointed face to ensure it was still straight and now it's warped. I didn't measure but it must be off by 1/32". I tried the oak first and I thought that perhaps I released some tension but the maple (which I thought was really stable) had the same thing.

Any of you guys have any thoughts what I did wrong?

Yes - I can tell you exactly what just happened. You just moved one step up the learning curve - that's what just happened. Everyone here has taken that exact same step - welcome to the club. :D :D

Here's what you just learned: When you cut lumber - whether it is ripping a board, or resawing a board, you are releasing stresses that are built up in those long fibers, and they are delighted to be set free. You, of course, are somewhat less happy.

Similar thing I did just last week: 6/4 maple rough board, cut to 30" lengths. Jointed one face, then surface planed the other. Nice, flat hunks of wood. Ended up just shy of 1-3/8". Then - resaw [I used a BS, but it doesn't matter]. Then, rip about 1/2" too wide. Then, I let the 6 resawn, ripped boards just....sit....there...on...edge...[for even air circulation].....for 2 days. They bowed about 3/64" - more-or-less the same as yours, and the crook from the rip was less - not quite 1/32". Joint the resawn face, and joint one ripped edge, then surface plane and rip to final width. Ended up just over 5/8" thick - my target was 1/2" or better. Perfect. Then, glue-up some nice maple drawer bottoms.

You have to cut wood oversize, and let the stresses move the wood. This will happen to bone-dry wood. You will remember this lesson forever.

Have fun.

[Neil Brooks]

Yep.

If you search the web, you'll find terms like "case hardening" that describe, to a "T," what you just experienced.

There are methods to prevent this, in the drying stage, but ... if you get a board with this sort of pent-up aggression (;)) ... you'll have to curse a lot, and then run it through your jointer/planer to get it back to the dimension you need.

Which is a major reason why it's good to start with fairly over-thickness boards, when you start resawing -- gives you some slack to plane them back to final dimension, later....

[Jason Saiki]

Thanks Guys...Lesson learned. I just didn't think it'll move that much.

[Neil Brooks]

By the way .... while case hardening will usually cause the resawn board to move _immediately_, higher MC on the inside than on the outside will cause the resawn board to move ... say ... overnight.

Either way, you're at the planer, but they ARE two different causes.

[Don Morris]

And let it sit for a while before you try to plane the sides parallel again. I was told/read, can't remember source that it takes a while for all the stresses to get released. A few days perhaps, just not immediately.

[Neil Brooks]

Totally agree with what Don said.

By recall ... it's sort of "2-3 days, if you must, but a week is better" (between re-saw and final dimensioning), and -- in a perfect world -- you'd sticker and stack it FOR that time.

[John TenEyck]

1/32" isn't much, really. I've had a lot more; big banana bends in some boards. The reason could be internal stresses or a difference in moisture content, as others have pointed out. You may find it hard to believe that it could be moisture content after the board sat in your shop for 6 months, but if it came in a lot higher or lower than the equilibrium moisture content of your shop then it could be. Anyway, I would set the boards on edge on some stickers for a day and see if they straighten out. I've had a lot of boards straighten back out after sitting over night. Whether it was moisture or stresses I couldn't say, but they were flat again which was good enough for me.

[Lee Schierer]

Stack and sticker those boards on a flat surface and let them set a week. Which way did they change? Was the bowing along the 3/8" edge or on the 5" face? Your resawing with your TS might have heated the inside surface of the cut and reduced the moisture slightly causing the new exposed face wood to shrink.