Interesting Experience with Wood Movement

[Mark Roderick]

I thought I would share a recent experience with wood movement.

I'm building some jewelry boxes from "stringy" red mahogany. I cut the pieces to lengths of about 36 inches and ripped them to near-final width, and then followed my normal procedure to flatten the stock. Not owning a jointer, I flattened one side of each board with handplanes, then ran them through my planer, flat side down.

This procedure always works. . . .but not this time. After running them through the planer, each of the pieces was significantly twisted and even a little bowed.

So I thought to myself, I must have done something wrong. Again I flattened one side of each board by hand (I hadn't planed to final thickness the first time) and again ran them through the planer. The same result: all boards came off the planer twisted and bowed.

I guess this just proves how "interesting" wood can be.

[Sam Yerardi]

It can be caused by a lot of different things. One is tension that has 'grown' into the wood perhaps from where the tree grew, the angle on a hill, etc. It is referred to as reaction wood sometimes. Sometimes you can see from the outside looking at the bark (wildly twisted, for example) that the wood inside is probably going to be reaction wood. Once it's in a board and has been planed, dried, etc., that movement may stabilize until you expose fresh cut wood to its environment or you cut into the wood in such manner as to let the forces within the wood do what they're trying to do.

[Greg Cole]

Might be moisture, might not. If ya have access to a tester, get your hands on it. .
Sometimes Mother Nature wins and when she wants to win there's no stopping her..... either finish making sawdust out of it or toss it aside.
I had some walnut that is either large limbs cut into boards or is from a funky tree, cause no matter what tact I take to mill it, it winds up thinner, narrower etc... but just as wonky as I started.

Cheers.
Greg

[Mark Roderick]

I don't think it's a moisture issue, because the wood twists as soon as it's put through the planer - I mean instantly - not after it's left to dry.

It's got to be a built-in tension. And considering the small amounts of wood I'm planing off, the tension in that board must be pretty remarkable.

[Greg Cole]

Better to find that out now that at the TS..... DAMKHIT.
To quote someone from the Creek..."I've got a better launch record than NASA".... I think it was Al Willits maybe? Ah well, was snot out the nose funny at the time.;)
Reaction wood, or whatever you want to call it, is amazingly powerful much akin to the force of seasonal wood movement.... you just can't stop it.
Call it kindling wood.

Greg

[Peter Quinn]

When you say 'Red Mahogony', do you mean African Mahogony? I've seen african mahogony with the ropey grain do some very wild things like you are describing. I've seen well acclimated sapele behave very badly as well.

I remember trying to flatten some 12/4 sapele for leg stock, with each pass over the jointer (very light passes mind you) it seemed to bow the reverse way, so I would flip it over and try again, and it would bow on me again! I stopped and checked the jointer for some gross misalignment, but it was right on. I checked the moisture. I even jointed some scrap boards to make sure I wasn't going crazy or having a brain fart. I stopped when I got to 8/4 and still didn't have flat stock, and it is still sitting in my shop, perhaps for a curved apron someday?

Its really cool when you gang rip a 24" wide board and see the cuts coming out of the machine headed 5 different directions! I guess they call it reaction wood because it always gets a reaction out of the guy trying to use it.

[Chris Padilla]

Try ripping the wood (I know, sacrilege!) but not on a table saw...rip it on a bandsaw or use a circular saw...see what happens.

Wood: a fickle medium!

[Ted Jay]

I don't think it's a moisture issue, because the wood twists as soon as it's put through the planer - I mean instantly - not after it's left to dry.

It's got to be a built-in tension. And considering the small amounts of wood I'm planing off, the tension in that board must be pretty remarkable.

How about using a hand planer, same thing happen?

[Joe Unni]

Mark,

I've had perfectly jointed and thicknessed sapele mahogany twist on the outfeed side of my table saw whilst making a 1" rip. Thankfully my splitter was in place or I would have been competing for the NASA record ;).

Sounds like a piece of reactionary wood. Kindling!

-joe