Warped Iroko

LONG_KEELER

LONG_KEELER

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Last spring, I made up two cockpit locker lids in Iroko about 2'6" by 18" . Thickness is about 20 mm.

After this winter, they have warped so that the edges will not bear down on the supports.

What did I do wrong ?.

Should I have glued supports ? or is it a grain thing ? . The grain is aligned fore and aft.

Can anything be done .

I thought of just reversing them. They are sat on a lot.

Thanks on advance.
 
LONG_KEELER said:
Last spring, I made up two cockpit locker lids in Iroko about 2'6" by 18" . Thickness is about 20 mm.

After this winter, they have warped so that the edges will not bear down on the supports.

What did I do wrong ?.

Should I have glued supports ? or is it a grain thing ? . The grain is aligned fore and aft.

Can anything be done .

I thought of just reversing them. They are sat on a lot.

Thanks on advance.
Click to expand...

Sorry I don't have a ready answer, but your question reminds me of seeing the difficulties of regular instances where the machinist in our joinery shop swore as a straight plank of Iroko when ripped down would spring into two banana shaped pieces. This tended to be instant due to the twisted grain rather than a long term problem.
See this link which makes brief mention.http://www.timbersource.co.uk/hardwood/other-ranges/iroko/

In the longer term it was normally reasonably stable but There was one of a pair of iroko doors we had to replace one leaf after a year. Even then it transpired that there had been the beginnings of a twist straight after manufacture.
Iroko is a somewhat unpredictable resource.
 
Nothing wrong, you were just unlucky to have used a bit of iroko with a mind of its' own. It is very prone to movement after it has been machined. I have a number of ex-school science bench tops, all perfectly flat and straight, and occasionally I rip one up into suitably sized lengths for a job, and the amount they can warp and twist is incredible, even though the wood is probably 50 years old.
What to do depends on how they are constructed, but assuming they are made up from a couple of wide boards:
1. Mark the top surface with a pencil
2. Rip the tops into narrow strips, say 40 mm wide, with a bandsaw
3. Flip every other strip over, so the top is now on the bottom
4. Glue the strips back together (you will need to add a strip or two to make up the width and compensate for the saw kerf). I would use epoxy personally, others might suggest cascamite which I have always found to be useless long term, or PU, which may be ok long term but can be very messy to use on a job like this with multiple glue lines.
5. Clamp it flat on a polythene covered bench top while the epoxy cures. Wipe as much uncured epoxy off the surface as you can with rag/meths to make the final cleaning up easier.

Other suggestions might be to cut a series of saw kerfs with a circular saw on the underside, clamp it flat and glue in splines. I have a cupboard door in the house that proves that won't be a success. Or to steam it for an hour and then clamp it flat while it dries out - which might work if you can constrain it in some way for the rest of its life.
 
johnphilip said:
Sorry I don't have a ready answer, but your question reminds me of seeing the difficulties of regular instances where the machinist in our joinery shop swore as a straight plank of Iroko when ripped down would spring into two banana shaped pieces.
Click to expand...

I have experienced that effect. I ripped a straight piece of 1" X 4" iroko that had been in a dry garage for a few years, hoping to make two lengths of 1" x 2" (less the width of the saw blade of course, before the pedants pile in!) and ended up with two curved bits.

Iroko certainly is weird stuff and it can cause unpleasant allergic effects, eg rashes, eye watering and itchy balls.:D

What would I do in the OP's case? Compromise. Make new lids out of marine ply and fit iroko (if he really wants iroko) lippings.
 
Boo2 said:
You used Iroko.

Remake it using a different wood.

Boo2
Click to expand...
Such as?
Despite the problems with stability and the need to be a bit careful with the dust from machining, I can't think of another solid timber that is easily obtainable, fairly cheap and above all so durable as iroko. There are certainly timbers that are as durable such as teak (if you can afford it), greenheart and keruing (neither of which I would ever consider machining).
 
The answer is to cut the wood into strips about 50mm wide, lay them out in the sequence you cut them. Turn every other one over and glue them up after cleaning the edges with a solvent to remove the oil. If your wood is quarter sawn you may get away with wider strips.
 
If you have suitable equipment and motivation, sawing the things up and remaking them (as suggested) is probably a good idea.

Reverse them for this season and see how you get on. Fitting strongbacks to the underside will help, but to be really effective they have to be deep, which will intrude into the locker. I would live with it and keep a look out for some suitable bits of used timber.
 
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