Thread: Trying to flatten some maple - heeelp please!

That may work... temporarily. Odds are very, very good that the bow will return when the wood dries out properly, 'cos that's where the wood "wants" to be.

I'd put the timber in the kitchen - or wherever the stool will spend most of it's time once it's in use - and let the wood acclimatise. It may bend more, it may straighten out a bit or it may stay the same: it all depends on how the average humidity in the kitchen (or wherever) compares to where it is now.

Once the wood has acclimatised - about 6 weeks for that thickness, less if the wood doesn't seem to be moving at all [fingers Xed] - then dress the timber properly square.

If losing that 3mm thickness worries you, then you can rip the board down the middle, flatten both halves, joint the edges square again and butt join 'em back together with biscuits/dowels/whatever. That way you'd only lose a mm and a half, at a guess.

After doing what Skew said if it is still bowing you can varnish the outside of the curve. As the varnish dries it will pull the wood back flat again.

Originally Posted by Pagie

After doing what Skew said if it is still bowing you can varnish the outside of the curve. As the varnish dries it will pull the wood back flat again.

I'd recommend against that. It's best to get the wood as flat as possible in an "average" environment and then seal both sides. Applying a finish to one side doesn't "pull" the wood back in, what it does is reduce the rate at which that side can absorb moisture. So, the "unfinished" side will absorb moisture more quickly. This will possibly straighten out the cup more quickly... but on a humid day will also cause it to cup more quickly!

Not that I'm saying it wont work. It will... under specific ideal circumstances. eg. a site that's air-con'd 24/7, 365 days a year. Sadly, that's a rarity rather than the norm.

You really are better off getting the timber square in "average" humidity and then sealing both sides.

Which'll reduce the timber absorption rate all over and make it take longer to cup. You cannot prevent cupping... all you can do is slow it down. And hopefully, by the time it starts to move in one direction, the weather/air-con/heater cycle has changed before it moves too badly in one direction and it starts to move back in t'other direction.

It's one of the less talked about principles of good design, really.

Hi Skew (your name is an interesting one, that's for sure!...),

a big thanks for the insights, which I really appreciate. I'm trying to learn all the time and am enjoying every step of the way. Your generousity is wonderful!

The piece in question has been acclimatised to the kitchen (which is probably where the warping originated) and so now I've done so much work on it (assuming I'd be able to pull it into shape later), it's a bit harder to throw! Probably the slight bow won't matter too much, but given there will be 3 fairly decent (19mm square) wedged through tenons, perhaps if I do attempt to flatten it a bit, dry it and then put it together, then possibly the wedged tenons will assist in keeping its shape.

Whatever happens, it's no disaster and will serve to teach me a lot and also add weight to the argument that I simply *have to have* a planer/thicknesser... (..and a big mutha of a bandsaw, a decent jointer, a... "hello Carbatec"!).

Anyway, when this is finally completed, I will photograph it (along with a few other projects on the go) and will post for the amusement of others!

Again, a big thanks and fingers crossed...

Cheers,
David

Re your bowed board was it acclimatised on a flat surface or stickered up off it so the air could get to both sides?
If the former turn it over and then once its flattened out sticker it up and put some weights on it for a few daze.
If you want to speed up the process chuck it on the grass bowed side down it will absorb moisture and straighten out quite quickly.
Wood moves you will never stop it just build stuff that accomodates the movement.
H

Hello Mr/Ms Clear Out (another interesting name...),

the board was acclimatised equally on both sides so should be OK. I should have known better when I bought it (or driven home via Carbatec and picked up a planer/thicknesser...)

I'll have a think where to from here - plenty of time while I complete a few other jobs(and put an end to the missus telling everyone that "David has started a lot of projects but finished none...")!

In this case it probably doesn't matter too much regardless, in that it's the top of a stool (load bearing) and I've put it bowed side up (dished down).

I'm using the following plan (slightly modified) using Maple with Jarrah for the wedges. Fingers crossed!

http://www.finewoodworking.com/Proje....aspx?id=30987

Cheers and thanks for your post,
David
PS. I'm nervous posting the intended result before the actual one... Long ago I discovered in golf that choosing the landing spot after hitting the ball has resulted in much greater accuracy...