Hooray for me....... I inherited a whole lot of usable plywood.... but the stuff was stored badly sort of on it's side... bottom line, it's warped. I fed it through the saws and got all the panels cut for 2 T39's....... To try and smooth them out a bit before screwing and gluing begins, I layed them on a flat concrete floor and put a whole bunch of weight on it to hopefully flatten it out. You think in 48hrs it will improve? I sure hope so.
Any good tips for dealing with warpage?
Dealing with Warpage......
Dealing with Warpage......
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Bill Fitzmaurice
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Re: Dealing with Warpage......
Store it flat, weight it down with cement blocks. What remains will get pulled out in the construction process.vexorgtr wrote:Any good tips for dealing with warpage?
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Frankenspeakers
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You have my sympathies... I bought a 4*8 of 'radiatora' pine and the consarned stuff warped the longer I had it. I had the lumber guy dig down in the pile too because the top pieces looked warped and thought I got a straight one... well it was straight at first. couple or three weeks later and the 30 * 48 pieces were dipping 1/2 -3/4" in the middle. Lotsa clamps and braces later and its almost straight... hopefully when the bafle board gets screwed to the back/frame everything will straighten out. HAH! the good thing is however... no parallel sides 
(oh well, the house is pretty crooked- maybe it'll fit) 
(oh well, the house is pretty crooked- maybe it'll fit) There is no technical problem however complex, that cannot be solved or finessed by a direct application of brute strength and ignorance.
"Gimme the hammer... Naaaw not that one, the freakin' big one- I'll MAKE it fit!"
"Gimme the hammer... Naaaw not that one, the freakin' big one- I'll MAKE it fit!"
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Frankenspeakers
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Yep, could be that. sticking with Baltic Birch with the little cyrillic stamp in the corner. Makes my Rooskie mechanic feel right at home 
There is no technical problem however complex, that cannot be solved or finessed by a direct application of brute strength and ignorance.
"Gimme the hammer... Naaaw not that one, the freakin' big one- I'll MAKE it fit!"
"Gimme the hammer... Naaaw not that one, the freakin' big one- I'll MAKE it fit!"
Interestingly, I've had good luck with inexpensive GP Sanded pine. Get the stuff that isn't knotty.... and it 4 plies thick. It's a cheap alternative I like to use while I'm "mastering" a build. Now pine plywood sold as "Sheathing" is really really really bad stuff.
Psychic Hamster Audio Works, Pro-Ject:Radiation, and Premium Computer Systems
http://www.premiumcomputer.cc
http://www.premiumcomputer.cc
warpage
Its been said before but the way you store wood matters a lot.
Wood warps because one side gets longer than the other (or is it that one side gets shorter than the other).
Try this quick test. Get a piece of ply say one foot square. Put it in the sun so that one side gets all the sun and the other is in the shade. See how short it takes to start cupping.
The sun dries out one side which shrinks. The other side is still "wet" so the board has to curl over.
Storing it flat is not the only thing to do. You need to make sure that both sides maintain the same moisture level.
Have you ever seen pictures of how they season woods? The wood is stacked, but every layer has a space to maintain constant moisture level in each side of the piece.
If you place your ply sheet flat on the ground, there will be a difference in moisture levels between sides. The best way to store it is on its edge and as upright as possible and not leaning against anything.
Since I don't have enough space to store sheet I buy it as I need it and use it quickly (before it has time to warp)
Wood warps because one side gets longer than the other (or is it that one side gets shorter than the other).
Try this quick test. Get a piece of ply say one foot square. Put it in the sun so that one side gets all the sun and the other is in the shade. See how short it takes to start cupping.
The sun dries out one side which shrinks. The other side is still "wet" so the board has to curl over.
Storing it flat is not the only thing to do. You need to make sure that both sides maintain the same moisture level.
Have you ever seen pictures of how they season woods? The wood is stacked, but every layer has a space to maintain constant moisture level in each side of the piece.
If you place your ply sheet flat on the ground, there will be a difference in moisture levels between sides. The best way to store it is on its edge and as upright as possible and not leaning against anything.
Since I don't have enough space to store sheet I buy it as I need it and use it quickly (before it has time to warp)