Question About Seasonal Wood Expansion

I’d have to agree that the design seems a little suspect with regard to wood movement.

I’m not sure how to do it without changing the design completely, but I don’t think I’d attempt to glue up pieces of plywood as if they were boards. In my experience at least, you can never glue up a panel so perfectly that it doesn’t need planing or sanding to level the joints. Try that on plywood and you stand an excellent chance of going through the top layer of veneer, resulting in an ugly mess.

-- Charlie M. "Woodworking - patience = firewood"

Good point Charlie. The design actually uses battens underneath the panels.

Each plank is screwed to these battens from the underside, so I’m not relying on glue on the plywood edges for strength and alignment. Hopefully this will eliminate the concerns you brought up.

-- Rex

Maybe so….. if I’m wrong, it won’t be the first time. :-)

-- Charlie M. "Woodworking - patience = firewood"

The saving grace for this looks to be the slatted shelves. It does not appear that they are edge glued(judging from the use of the cleats underneath, also the fact that they show the lines separating them). If it were solid from edge to edge(or glued edge to edge), there would be a problem. With the narrow slats, unless they are assembled tightly, then they can allow for movement . Each one is attached to the cleats underneath and they move individually, in reference to their fasteners, not as a whole shelf.

Edit: I agree with Charlie, I would not glue the plywood edge to edge. The strips are fine, just use the cleats underneath.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

Thanks Rance, your analysis makes a lot of sense. You are correct, the article doesn’t call for glue between the boards, but it does say to use clamps to pull them tightly together as you screw the battens on, with one screw in the center of each board. It looks like the author was taking expansion into consideration, but it still seems like there might be problems down the road. It would be interesting to see if the one he built has developed any cracks.

So I’m still glad I’m using plywood, and will definitely use the battens to attach things. I may still use glue on the long edges of the strips, but it would just be to make myself feel better. Or I may skip that and just glue/screw the battens to the bottom.

-- Rex

It is just conjecture.

If using solid wood, the original builder will likely have problems if he pulls them together with clamps before fastening. You actually want just a little bit of slack between each one. He is correct in putting one fastener in the center of each slat.

Even with ply, I would not glue them. You might consider tongue & grove.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

Hi Rex
I have helped student after student who have pulled plans and designs form magazines with bad designs and incorrect measurements and many times no thought to wood movement, You would think that someone publishing woodworking magazines would have someone who knows something about woodworking and how to check measurements. I’m glad to see you gave some thought to this design before just throwing it together.

-- W James Brokenbourgh Custom furniture maker http://artisticwoodstudio.com/