The following is written based on the premise that you have bought timber which is machined dead to size and where there is no leeway to take the wind (twist) out by means of hand planes and winding sticks
Is it a realistic expectation to unwarp the wood
Seriously? No
Will the wrapping it in a damp towel and leaving it clamped method actually work?
No, and worse still it will raise the grain and probably cause/accelerate other issues such as cupping. When you steam bend timber you have to steam it for about 1 hour for every inch of thickness to make it pliable enough, so you can hopefully see why applying a damp rag is whisltling in the wind. In any case, you presumably bought nice 8 to 12% MC (moisture content) kiln dried timber and you are now proposing to soak it - that's not good!
Is there a better method?
Start with straight timber and use the stuff in wind for short and small section components such as glazing bars where you can deal with or hide the defects. In reality, either it shouldn't have been sent out (supplier at fault) or you have stored it incorrectly (your fault)
1. Had I been doing the job I'd have inspected the material the minute it arrived and if it wasn't flat and straight, I'd have sent it back immediately. It is impossible to correctly mark out and joint timber with wind (twist) in it. Bow and cup, providing they are very minor can be dealt with (you can plane them out by hand), but not wind.
2. Assuming the timber was straight and square, there was no wind and cup (across the grain) and bow (along the length) were containable I'd have cut to length and cut the joints immediately and assembled it as soon as possible (i.e. within 24 hours)
3. TBH I live in the Pennines where we have a rainfall more akin to living in a tropical rain forest, so I've learned NEVER to take on joinery jobs at home from about early October until late March (our
really rainy season where the mushrooms round here have moss growing on them). Even so I never store any timber in my shed; if kiln dried stuff comes to me and I cannot use it immediately it always comes inside the house and is stored properly stickered in the living room (which as you can imagine makes me hugely popular
). Even then it is only for a couple of days at most, partly because I'm in fear of my life otherwise
Any advice on how id do this with a twisted piece of wood?
Again, you can't. In fact, if you think about it, the timber has been machined with stresses in it and how it has subsequently handled and stored has caused the stresses to put it in wind, etc. All you can do is replace it
The bowing isnt so much of a problem, it is the twist. As i join the cross pieces to the upright, the twist will put the cross pieces out of alignment on the other side of the door.
Any ideas on how i could pull the twists into alignment?
Again, you can't. Even if you could manage to untwist a piece which is in wind straight enough to get the door put together, the stresses still in the timber will often simply pull the door out of flat in due course. You need to replace the piece in wind with one which is straight. The only guaranteed thing you can ever do with material which is in wind is to cut it down to very short lengths and use it for short components, not frame elements. Sometimes, if the wind is only a couple of millimetres you can get away with it, but there is always the risk of the stresses in the timber causing the door to warp subsequently
Ive been thinking, the cross pieces should pull the twist out when connected to the opposing upright. The only question is, will a tenon 15mm thick x 40mm long be strong enough to hold 5mm of twist without breaking?
It won't break. but the joints won't pull up square
Alternatively if there is considerable risk that it wont be strong enough, could i not simply rout out a 10mm slot right through one upright, along the cross piece, and through the other upright, both top and bottom of the door, and glue a 10mm square metal bar in the slot finishing flush with the wood?
Or you could simply buy another straight piece of wood
You can faff around as much as you want, but a piece of timber in wind will always be in stress and will always pull a door frame out, if not to begin with, eventually. 44mm thick hardwood is not softwood studding or joisting. B-A, and is a darned sight stiffer and resistant to being twisted flat.
I have tried in the past to plane out wind from oak (on a jointer) only to find that when I thicknessed the timber it almost immediately went into wind again. Often I have been able to take out the wind by judicious surface planing, but that always needs to be done before the timber is thicknessed; it cannot be done afterwards without losing thickness. With 5mm of wind I'd expect to lose 6 to 7mm in the thickness to plane it flat and true
I'm afraid that some timber you just have to find other tasks for, such as making-up glazing beads which are small cross section and where you can control the stresses. That's why we talk about wastage factor in trade work. It's all part of the joy of working with wood because it is a natural material
