Forcing bowed panel into groove?

[Joseph Camden]

I'm making a queen size bed. The footboard will have a panel 10 inches high and 5 feet long, out of soft wormy maple. I resawed a completely straight 6 ft 4/4 board, and there must have been a lot of stress in the board because I got two 1/2 inches pieces and each has a bow of about 1/2 inches along the length.

Should I separate this into two panels with an internal divider like this

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Or can I force it into the groove and let that hold it straight? The joints for the frame are going to be drawbored m&t. Any advice?IMG_20180923_105030.jpg

[David Eisenhauer]

I always immediately clamp my freshly resawn panels with some cauls to a flat surface (usually one of my work benches) when leaving them overnight after cutting and they remain clamped until it is time to use them. If I don't use all of the panels when I start glueing, the remainder go back under the cauls until I get back to glueing. Can you clamp yours down flat on something and see what happens?

[Peter Quinn]

Could work if the frame stock is thick enough and the panels will flex. I like the clamp it flat a few days option, maybe its cauls to let both faces breath a bit? See where it goes? If its a tension issue the bow probably wont subside, if it was a bit of moisture equilibrium it might improve as it sits? Maple moves pretty fast and hard with changes in moisture ime.

[Joseph Camden]

This is good advice, thanks! When you do cauls, would you do one in the center holding the bow down, or bow side down and cauls at the ends forcing them flat? Or does it matter?

[David Eisenhauer]

For me, the number of cauls depends on the size of the panel. On e at each end and one across the center as a minimum. As I said earlier, I believe I have four sets (an upper and a lower for each location) to use on larger table top type items. I don't know what you will clamp your panel to, but in the case of 10" tall by 5' long, I could probably get by with one 6" from each end and one across the center. As I already have four sets, in my shop, I would likely add in a fourth caul for a "belt and suspenders" approach to the problem. make a few cauls and try some, add in more if it looks like it needs it. Be sure and add some packing tape or something similar to the face of the caul that will contact the panel if you are doing any glue up to create the panels. If they are one piece panels, than some type of no stickum is required. Let me wander down to the shop and take a photo of one of my caul sets for your viewing pleasure. As Stephen C says, stay tuned...………...

[Lee Schierer]

Quite often when you slice thick pieces into thin pieces, there is a moisture differential between the outside surfaces and the interior of the piece of wood. By cutting it in half you have exposed the difference and the wood will tend to move, which is likely what happened in your case. Now that your panels are 1/2" thick, your rails and stiles should be able to hold the pieces flat once you get them installed. Installation might be fun because of the bowing. You can wet the concave side and cover it briefly until it flattens out and then quickly insert the panel in the rails and stiles. Allow everything to equalize for a couple of weeks before you put any kind of finish on the assembly.

[David Eisenhauer]

Caul photos. Photo 1 shows using a set of cauls used to create a flat plane during a two piece glue up. Photo 2 shows a set (upper and lower) of cauls ready for use. Photo 3 shows single cauls used in the case of clamping/cauling flat down on to a bench top as in the case of keeping panels flat overnight. The camber in my cauls is fairly slight, so I wrote something on the caul to show which way they are to be oriented ("caul" goes against the wood) in use. When using the cauls in an upper/lower pair, I find it easier to use carriage bolts rather than clamps. Clamps are much, much touchier to keep on the ends of the cauls when adjusting the whole shebang. When using cauls to keep panels flat during a multi piece glue up, bar clamps are also used as typical to pull the sides of the pieces of the panel together for glue up.

[Wayne Lomman]

Do what Lee said. They are only 1/2" thick and will easily pull into shape. Cheers

[Brian Holcombe]

If they don’t flatten, plane 1/8” off the outside face and see if they don’t straighten out a bit.