# Need a stiffener for a large panel



## DickB (Jan 19, 2012)

I've made several of these large lake maps, about 2ft x 4ft, using select pine and have had no issues. The main panel is made from two 12" boards edge glued, and the frame typically 1×4, mitered joints held together with biscuits, with a routed slot in which the panel floats.

I made a larger one, about 3ft x 5 ft, and the project has warped. The 1×4 frame has not been sufficient to control warpage in this case.

I'm thinking I need to build a honeycomb-like subframe to be installed behind the project, not hexagonal but rectangular or square - maybe 8" squares? - out of 3/4" Baltic birch. The subframe would be hidden, but hopefully provide the necessary stiffness to prevent future warpage. (hopefully I have described this well enough to be understood.)

Any comments or suggestions?


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## wormil (Nov 19, 2011)

First I would nail down why it warped. Common causes are: too wet, finished only on one side, left in the sun, left on a concrete floor. Tables are bigger than that and do not warp if they are dried and finished correctly.


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## oldnovice (Mar 7, 2009)

One thing that causes warping is not applying finish to both side of the panel.
The unfinished side will absorb moisture expand and bow to the finished side.


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## dhazelton (Feb 11, 2012)

You could always screw a couple of angle iron ribs to the back. But if the wood wants to move it will just split.


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## dhazelton (Feb 11, 2012)

...or do your glueup out of more boards of a smaller width. Will be more stable.


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## DickB (Jan 19, 2012)

Thanks for the replies.

I removed the frame and found that the main panel was not warped after all, which leads me to believe that I messed up the frame when I built it.

BTW finish was applied to both sides, wood was dry, not in sun. I do often use glue ups of narrower boards, but in this case I want the grain to match as closely as possible and take care when laying out and choosing wood to do so, and use wider stock for that reason.


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