Dealing with twist

[Sauric]

Hi Everyone

I've been making furniture as a hobby for only a couple of years so still have a huge amount to learn.

I've made a chest of drawers and must now edge joint three boards to form the top. The boards are 20mm European oak, just short of a metre long. The front and rear boards are 140mm wide while the centre board is 180mm. The centre board is pretty good dimensionally but the front and rear boards are twisted to the extent that if I place the board on a flat surface and press down on one corner the opposite corner, at the other end of the board, will lift by about 2.5-3.0mm.

If I can avoid it I'd prefer not to plane the boards in view of the amount of material I'd need to remove and also that I'd need to reduce the centre board to a matching thickness (not to mention the fact that I don't have a planer thicknesser!). Hence, can anyone offer advice on how I might straighten these twisted boards?

Thanks in advance

Ian

 

[MikeG.]

You can't straighten twisted boards, reliably, other than by flattening them with a plane. You have two choices now........buy some more wood (not twisted, this time), or rip the twisted one length ways, flatten the bits and square it all, then glue it all back together again. You still lose some thickness, which you'll then have to take out of the other two boards, but not so much as if you try to take the wind out of the whole board in one go.

There is a really important lesson here, not just in wood selection, but in the quantity you buy for a project. You should never buy just enough to do a project. That just results in the sort of issues you have come across here. I'd suggest buying 50% more than you think you'll need, and putting the excess into stock for next time. Stick to 2 or 3 timber types, and you'll soon build up decent stocks of all of them, and you won't need again to be contemplating using unsuitable timber as you are at the moment.

 

[Sauric]

Thanks MikeG. Hmm, I was afraid that might be the case. Sounds like I may need to buy more timber

 

[thetyreman]

you could try and correct the twist but you'll probably find that 2-3mm means the final dimensions would be not the right thickness, also from my experience if wood wants to twist it will just twist, some pieces of wood are just like that, you might end up removing the twist and it twists again, which has happened to me more than once. Safest option and least time consuming is to get some new boards and use the twisted one in another project, as mike pointed out always get more timber than you actually need.

 

[That would work]

I would go with MikeG's ripping the boards and edge jointing in the most favourable arrangement to loose as much twist as possible... quite likely possible.
For cupping you can damp down the concave side and expose the convex surface to the sun/warmth to flatten it but a twist is different.... if it were me though I would still look at the annual rings and the twist and see if I could wangle some improvement by doing this, perhaps to half the board at a time.

 

[Steve Maskery]

Whilst doing the job again would be the best approach, I think you MIGHT just get away with pulling it down. How are you planning to attach the top to the carcase? If you are using buttons, then they can exert quite a bit of force. You might be able to pull down 2 or 3mm.

Given that you have little to lose except your time, glue the boards together and try to fit the resulting top. You don't need to do any more planing or sanding or other finishing at this point. Does it pull down onto the carcase? If it does, go ahead and finish it off. If it doesn't, you still have that wood to use for other projects and you will have learned a valuable lesson in the process.

 

[Sauric]

Thanks to everyone for your thoughts. I'm using buttons to attach the top to the carcase so I think the most pragmatic approach may be to glue up the top and see if the buttons will pull it in. If that doesn't work I'll learn the lesson and buy more timber.

Thanks again for your advice.

Ian

 

[woodbloke66]

You can't straighten twisted boards, reliably, other than by flattening them with a plane. You have two choices now........buy some more wood (not twisted, this time), or rip the twisted one length ways, flatten the bits and square it all, then glue it all back together again. You still lose some thickness, which you'll then have to take out of the other two boards, but not so much as if you try to take the wind out of the whole board in one go.

There is a really important lesson here, not just in wood selection, but in the quantity you buy for a project. You should never buy just enough to do a project. That just results in the sort of issues you have come across here. I'd suggest buying 50% more than you think you'll need, and putting the excess into stock for next time. Stick to 2 or 3 timber types, and you'll soon build up decent stocks of all of them, and you won't need again to be contemplating using unsuitable timber as you are at the moment.

I'd agree here with Mike; always buy more than you actually need and put the excess into stock. It's not too difficult to plane out the 'wind' on boards that are say, 150mm wide but you'll loose (as Mike says) some thickness so it really depends on whether or not you can get away with it? For example, if the boards as purchased are 25mm thick and you require a finished thickness of let's say, 20mm then you've got enough material within the board(s) to make them flat and true, bearing in mind that you plane more or less diagonally along the board and thus take off material from each end. If you do that, you'll need to constantly check with a pair of winding sticks that the board(s) is in fact, gradually becoming flat - Rob

 

[dzj]

Thanks to everyone for your thoughts. I'm using buttons to attach the top to the carcase so I think the most pragmatic approach may be to glue up the top and see if the buttons will pull it in. If that doesn't work I'll learn the lesson and buy more timber.

Thanks again for your advice.

Ian

A few kerf cuts on the bottom of the panel might also help.

 

[johnnyb]

20mm sounds like par boards. ie started at 1 inch and planed.then sold to your good self. all the above is good advice of course. but wood is a pain. first of course is plane then thickness just before joining. select the timber for the part. ie doors need to be straight other things dont.
try and glue it 2 at a time. so glue the twisted bits first with pieces of wood clamping the twist out then glue the straight bit on. get a panel without big steps then screw it to the carcase. forget buttons. just make the holes big ie 5mm for 4 mm screws.
as my mentor said "were not f#@$#ing nasa" another word he used for wood bodging was "we can wangle it now" wangling being making something that was less than perfect do its job.