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Flatning Top Wood?


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Quick question for everyone. I have a thin bookmatch set of maple that I'm going to use for a top. But I noticed that it has warped slightly. I was wondering if anyone had any ideas on how to flatten it? I thought maybe just wet it with a damp rag and press it between two MDF pieces for a day or two or week. Anyone have any ideas?

Thanks,

Scott

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If it has cupped then spritz the *concave* face with water in preference to wetting it with a rag. Then lay the board concave face down on a flat surface and weight the top with a sandbag or whatever at the apex of the board where it is furthest off the flat surface - generally the middle of the board. If it's not a simple cup - like a twist - you may have to repeat this process a couple of times, flipping the board. Simple clamping might crack your board....light rag damping of the surface won't soften the board, it'll just cause the surface fibres to expand and lift a little. You need to wet the cupped side to provide a little expansion force back "against the cup" with a little weight to tease it back into shape (technically, out of shape if it's cupping to it's natural rest state!). How thick/thin is the maple? If it's <5mm then it should stay flat when glued to a body.

Edited by Prostheta
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Thanks Prostheta for the link, and Drak thanks for the thread. I'm trying to flatten it now. I went with the method of spraying the concave side with water and put it covex side up on my bench and put a bag of cat litter on top of it. So will see how it comes out.

On another note Drak you have any pics of that burl guitar finished it looks great. Once I flatten this maple it going on top of chambered walnut and going to just put an L.R. Braggs T-Bridge no other pick-ups. I Want an acoustic but don't like the feel of an a true acoustic guitar.

Anyway, Thanks again

Scott

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Thanks Prostheta for the link, and Drak thanks for the thread. I'm trying to flatten it now. I went with the method of spraying the concave side with water and put it covex side up on my bench and put a bag of cat litter on top of it. So will see how it comes out.

On another note Drak you have any pics of that burl guitar finished it looks great. Once I flatten this maple it going on top of chambered walnut and going to just put an L.R. Braggs T-Bridge no other pick-ups. I Want an acoustic but don't like the feel of an a true acoustic guitar.

Anyway, Thanks again

Scott

use a steam iron ,steam both sides and keep steaming after a while it will become flexable you should be able to push it flat the clamp it between two straight boards or on a table or something

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Not done yet, still under construction.

I know and understand where some people say to wet one side only, the absorption of water on that side will expand the cupped side, I've done that a lot of times, but I do it a little differently these days.

I -thoroughly soak- the wood then clamp it, as I am trying to re-adjust the entire structure of the wood at a subatomic level, trying to wet the whole thing so the pores can all go limp and relax themselves, then when they dry back out, they are re-aligned straight.

Sort of like a chiropractor... :D

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Not done yet, still under construction.

I know and understand where some people say to wet one side only, the absorption of water on that side will expand the cupped side, I've done that a lot of times, but I do it a little differently these days.

I -thoroughly soak- the wood then clamp it, as I am trying to re-adjust the entire structure of the wood at a subatomic level, trying to wet the whole thing so the pores can all go limp and relax themselves, then when they dry back out, they are re-aligned straight.

Sort of like a chiropractor... :D

About how long do you leave it clamped or with weight on it?

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I know and understand where some people say to wet one side only, the absorption of water on that side will expand the cupped side, I've done that a lot of times, but I do it a little differently these days.

I -thoroughly soak- the wood then clamp it, as I am trying to re-adjust the entire structure of the wood at a subatomic level, trying to wet the whole thing so the pores can all go limp and relax themselves, then when they dry back out, they are re-aligned straight.

Ummm....you need an atom smasher like TEVATRON to achieve subatomic rearrangement! You've gone really belt and braces recently Drak :-D We'll buy you a hammer to go with your WOD set, next birthday. :D

More likely you would need to steam the wood to reälign it in a comfortable "rest" state, same as how acoustic sides are bent or ship hulls are moulded. As a sideline, the town where my closest Finnish relatives live are building a wooden ship as a community project. Sorry, this is in Finnish only: http://www.kaljaasi-ihana.fi/

The reason I mention this is that huge long timbers are steamed for a couple of days each in long enclosures and then bent over the ships hull structure to dry/cool into their new shape as the "glue" that holds the fibres together sets. I would love to be in Luvia providing help to this project than in the UK right now :-\

This method of heating wood up (using steam as a heat transfer medium) allows the fibre structure to slip and realign as the "glue" (cellulose?) which binds them together as "wood" relaxes. I think that simple overall soaking and clamping does this in reverse, with the forces of the expanded wet fibres being forced to slowly relax back into the flat clamped shape. The soaking/drying is completely different to the process of drying wood "from green" as that is the cells giving up their water content and not the areas in between or whatever. Either way, whatever works right? :D

On reflection, I think the application of the wood is important here - if there isn't sufficient glueing contact area on the destined workpiece, this cupping/warping might become an issue if the wood decides that it *really* wants to be in a non-flat shape. Do you have any photos of the patients, Scott? Seeing the endgrain might reveal a little as to how much cupping you might expect in the long term....flame and quilt are usually found on the quarter and quilt on the tangential plane (flatsawn) respectively. The direction of the grain and how that changes across the board can be pretty telling as what to expect as it seasons. There are plenty of other people on here with more direct experience with cutting/drying wood than myself however.

Edited by Prostheta
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Oh, I was just kidding with the subatomic stuff for chrissakes :D .

And you are correct, when looking at un-bending wood, the same principles apply as when you -are- actually bending wood, that's what you're trying to do in a sense, and water + heat are the two most common means to make wood do what you want it to.

I'm just saying that using lots of water with no heat usually will get me what I want, but I agree with you, water AND heat are the most effective, but not everyone wants to go to all that trouble, when just water, some hard boards and clamps will do the trick.

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I know and understand where some people say to wet one side only, the absorption of water on that side will expand the cupped side, I've done that a lot of times, but I do it a little differently these days.

I -thoroughly soak- the wood then clamp it, as I am trying to re-adjust the entire structure of the wood at a subatomic level, trying to wet the whole thing so the pores can all go limp and relax themselves, then when they dry back out, they are re-aligned straight.

Ummm....you need an atom smasher like TEVATRON to achieve subatomic rearrangement! You've gone really belt and braces recently Drak :-D We'll buy you a hammer to go with your WOD set, next birthday. :D

More likely you would need to steam the wood to reälign it in a comfortable "rest" state, same as how acoustic sides are bent or ship hulls are moulded. As a sideline, the town where my closest Finnish relatives live are building a wooden ship as a community project. Sorry, this is in Finnish only: http://www.kaljaasi-ihana.fi/

The reason I mention this is that huge long timbers are steamed for a couple of days each in long enclosures and then bent over the ships hull structure to dry/cool into their new shape as the "glue" that holds the fibres together sets. I would love to be in Luvia providing help to this project than in the UK right now :-\

This method of heating wood up (using steam as a heat transfer medium) allows the fibre structure to slip and realign as the "glue" (cellulose?) which binds them together as "wood" relaxes. I think that simple overall soaking and clamping does this in reverse, with the forces of the expanded wet fibres being forced to slowly relax back into the flat clamped shape. The soaking/drying is completely different to the process of drying wood "from green" as that is the cells giving up their water content and not the areas in between or whatever. Either way, whatever works right? :D

On reflection, I think the application of the wood is important here - if there isn't sufficient glueing contact area on the destined workpiece, this cupping/warping might become an issue if the wood decides that it *really* wants to be in a non-flat shape. Do you have any photos of the patients, Scott? Seeing the endgrain might reveal a little as to how much cupping you might expect in the long term....flame and quilt are usually found on the quarter and quilt on the tangential plane (flatsawn) respectively. The direction of the grain and how that changes across the board can be pretty telling as what to expect as it seasons. There are plenty of other people on here with more direct experience with cutting/drying wood than myself however.

I'll post some pics this weekend. It's really not that bad but needed to be flatened as I didn't want to take a chance of it deciding it wants to stay cupped after I already had a finish on it. I have left it for two days with weight on it an going to check it tonight, but looking at the edges and taking some weight off, it looked pretty good.

Guess I'll have to return that subatomic partical acelerater in the morning. I hope Wally World takes returnes on them.

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