Warped lumber fix?

[RJD2]

I have a 6' piece of hard rock maple that is 3 1/2" wide and 1 1/16" thick that is warped in the form of one side being slightly cupped in the center. Is there any method to straighten the board? Thanks.

Ron

[Tom Slick]

without jointing/planing?

[Knottscott]

You can joint it in one piece as is, but you may lose quite a bit of thickness getting it flat...or you can rip it down the middle, then joint it flat and reglue it.

[Papa]

Warped Board

I saw an episode of The American Woodshop in which Scot put a warped board out in the sun on the grass for several hours to straighten it. I've never tried it myself, but it seemed to work for him on the program.

Papa

[LCHIEN]

I've always figured that if you need much smaller pieces than the original they cutting it to size and then flattening would present less work and lost material than flattening first, then cutting to size.

For example a board cupped 1/4" on 3 inch width would require planing 1/4" off the top and then the bottom to make it flat, a loss of 1/2".

However, if you needed only 1" strips, then you ripped it to 1" wide pieces, the cup would of each piece would only be 1/3 of 1/4" or about .08". So you would have to plane off .083 off top and bottom for a loss of only .166, 1/3 as much as you would have lost had you plane the whole board flat.

Likewise, a 6' board with a 1/2" warp would require trimming off half an inch right and left. but if you only need 12" long boards, then the warp per board will be 1/6th of 1/2" or about .083" you would only need to reduce the width by 2x.083 or .166" to make usable straight pieces.

I'm assuming the cup or warp is uniform and not all at one point due to a knot or something.
Also, you might be careful, sometimes cutting a board into smaller pieces, the individual pieces then relieve stress and take on a new shape of their own! If you do cut it up, might be good to wait a day before trying to straighten the smaller pieces!

[herb fellows]

I'm currently working on the same thing with a 3 ft piece of warped crown moulding that was part of a frame for a beveled piece of glass in a door.

So far, I've clamped it down to a straigth 2x4 which I've put an absorbent piece of cotton cloth around. I wet it down a couple of times a day with a spray bottle It's been a week now, very little progress:-(. I expect if it does any good, it wil probably take at least 2 weeks. It's about 1/4" rise on each end from a flat center. I'll keep you posted if it works.

[poolhound]

I saw an episode of The American Woodshop in which Scot put a warped board out in the sun on the grass for several hours to straighten it. I've never tried it myself, but it seemed to work for him on the program.

Papa

I have tried this more than once and the theory is good but the practise less so. I have had boards that show signs of straightening after doing this but once they are returned to the shop to dry out and reaclimatise they regain most if not all of their warp/cup/bow etc.

if the board is rough its going to move to some degree when its milled anyway. IMHO its always a good idea to mill rough stock in 2 stages (unless its really very dry) and always aim to plane equal amounts from each face.

I have one piece that I keep in the shop as a reminder of this. I think I must have experiemnted when I got my new planer a year or so ago and planed only one face and it now looks like a banana!