Question re: resaw into 1/4" boards

[Grant Stevens]

Question for the masses:

I did my first attempt at resawing - cut some quartersawn white oak into 1/4" boards for making some boxes. When I came back the next day, the boards were quite cupped and a little bowed/warped. The rough sawn board that I started with was kiln dried, and in my shop for a couple of weeks (although I did not stick the moisture meter in it before I milled it).

So, what did I do wrong? Do you think that this is due to the lumber having moisture inside, or stresses in the wood? I have never milled lumber so thin, but I am assuming that this is not normal. Any advice would be appreciated!

Thanks,
Grant

[Jared Cuneo]

Are you positive that they did not cup right after sawing? This is fairly common, especially in exotic or figured woods though not generally seen in quartersawn stuff (at least in my limited experience). It seems to happen a lot in very flatsawn boards which come from closer to the center of the log (I think). I generally expect a little movement and cut slightly thicker so that I can run it through the planer or jointer should the need arise.

The worst offender I had was some Sapele. This stuff warped as it went past the blade and I swear it had twisted almost 90 degrees by the end of the cut....I wound up using it for short splines....

JC

[Rick Gifford]

A guess is it had some moisture and when you cut it thinner it dried out a bit faster and cupped on you.

My suggestion for next time is to resaw a bit thicker and joint, plane it down to size after it sits in the shop a day or so.

1/4" is pretty thin!

I will be doing some resawing for boxes soon. I was leaning towards 3/8". Your occurance might help me decide to stay a hair thicker.

[George Bregar]

I resawed 4/4 QSWO to veneer my Morris Chair legs to get four QS faces...also cupped very badly. Ended up just using a lock miter joint so I didn't need it. Flattened the cupped 1/2 on my jointer and planed it to 3/8 for the back slats thankfully.

[Jim Becker]

The moisture content in a board is not always the same at the surface as it is internally. When you resaw the material, you often end up with an imbalance that results in a little bit of what you describe. Best practice is to resaw with enough stock left over to allow for machining flat after a few days in stickers so the moisture content can equalize. Some weight on top when stickered isn't a bad idea.

[Gary Keedwell]

Moisture is one element in the equation. Natural internal stresses are another.
Gary

[Tony Joyce]

We resaw 1/4" & 3/8" out of 4/4 & 5/4 weekly from most domestic and several exotics species. We resaw(generally 1/8" over size), plane(.03" over thickness) and sand(1 pass each side to 120). I very rarely see any cupping. Some of these bundles can lay for a month or more before selling. This is most likely a drying problem. Some kiln operators do not stress releave.

Tony

[Steve Leverich]

Tony, sounds like you're a good source for my question - I just bought 2 units of 4/4 tan oak (un-surfaced) and it's kinda wavy (a few of the boards), widths from 2" to about 12", most is about 10 feet long. Still have to find a semi-permanent place to sticker it and want it to dry as flat as possible.

What's your recommendation for sticker spacing, etc, for best results? Planning on letting it stay there (inside the shop, on concrete) for at least a year. Thanks, and sorry for the hijack... Steve

[Tony Joyce]

Steve,
I'm no expert on drying, just what I picked-up over the years. That said, sticking should be about 14"-16" apart, sticks must be dry material, uniform size and the pack must be started out flat. If it fresh cut the ends should be coated to reduced cracking in the ends. Hope thats of some use, I probably forgot something.

Tony

[Grant Stevens]

Thanks to all,

The cupping did not occur right away - I laid out the boards on rails to let both sides get air, and they cupped overnight. I made the mistake of planing to the final thickness right away, so I guess I'll have to chalk this up as a learning experience. The 1/2" was ok, so I guess that I was too aggressive going to 1/4" without taking the drying status into account...

Thanks to all for the good advice.

Grant

[Jim Becker]

Steve, stickering wet wood in your shop is not going to provide the ideal air flow for good drying. Air flow is the name of the game as it wicks away the moisture as it leaves the wood. Stacking outside where normal wind, etc, is able to pass through the pile is what you really want. Get it at least 6-8" off the ground, space your dry stickers about 16" apart as Tony suggests and put a cover on top of the pile to avoid any standing water, ice or snow directly on the boards. The sides should be uncovered so the air can get through the pile. You also want some weight up top, especially with oak.

[Steve Leverich]

Jim, thanks for the suggestion - couple of problems that would make it difficult for outside storage here in rainy Oregon - we live on a hill (flat spots are at a premium) and so far, any un-finished wood that's been left outside (even under cover) tends to grow mold. I have a spot in the shop that's flat and bone dry, thought I could use that. I intend to space the stickers as suggested and leave about an inch between boards side-to-side, and I have a couple of 16" oscillating fans I planned to set up on low for air circulation.

I found a couple of blurbs on Tanoak on the web that suggest this stuff is more susceptible to warp than oak by a bit, so maybe I can find an old car or something to set on top of the pile while it's drying ;)

Since a lot of this stuff is wider than 6", I'm startin' to wish I'd found the Creek BEFORE I bought a new PM 6" jointer :( - guess I'll be building a sled for the planer sometime next year...

Thanks again guys, as usual the Creek's the best... Steve

[glenn bradley]

I always (now anyway) mill oversize, let the material acclimate some more (a couple weeks at least) and then finish my milling process. KD or not, material will change after re-saw, jointing, planing, ripping, etc. Some more-so than others.

[Alan Turner]

We resaw a bunch. White oak is nearly always an issue. White oak does not let water pass through. Think of a wine cask. My thinking, non-scientific, is that white oak is a prime candidate for both bowing and cupping when one resaws, and the reason is that the m/c is different at the surface from the inside portions. Mill it heavy, let it deform to its heart's content, and then remill.

[Larry Rasmussen]

Gilmerwood is a hardwood re seller that posts individual pieces on line and has what appears to be kind of a boutique level internet business. They appear to do a fair amount of milling and also offer less exotic fare in their Oregon location. Anyway it is always fun to browse the site for entertainment, they have beautiful stuff.

I called and inquired about them doing a re saw on a piece of 5/4 maple to split it for a couple of speaker fronts. I was told that in general they would only re saw stuff they had dried by air or knew that was air dried correctly. Whether imported or domestic anything kiln dried ineveitibly warped or cracked. He attributed this not so much to the act of using the kiln but to the fact that in their opinion it is dried in too much of a rush to keep cash flow up.

This was a short conversation and full of generalizations but it really changed what I thought might be possible in my shop. I had kind of pictured keeping the wood for a while to equalize the moisture content in the shop and just slicing away. Now I figure if I want to go that route I'll post a question regarding other's experience with each variety I wanted to work with or at least plan on small batches and same day assembly.

Hope that helped.

Larry R