I am building a pass through that will have a narrower piece of poplar
below a wider piece of red oak. I want to join the pieces together so
they are solid, but am concerned about differential wood movement
I'm new to woodworking, and this is the first time I have used
multiple species that will be joined together this way, so any
comments would be appreciated.
My initial thought was to put in a couple of screws in elliptical
countersunk holes so that the wood can move independently, but I don't
know if this is really needed.
Thanks for any help,
If the grains of both pieces are in the same direction and the length
is <10 feet glue them together. To be a truly strong joint, consider
making a grove. If you are serious about woodworking use metal
fasteners as a last resort.
The pass through is 4"x4' and currently has a 40 year old piece of
countertop on it. We wanted to keep the thickness of the countertop
(~2") and wanted a distinctive feature, so I had thought about a
stepped or scalloped edge. So, we bought a 1"x10"x8' piece of poplar
and a 1"x12"x4' piece of red oak, both plainsawn.
The kitchen side of the pass through will be straight edges about 1"
into the kitchen. Once through the wall, the poplar will be curved
with a routed edge, maybe a cove. The red oak (the top) will have the
corners rounded but otherwise be full. Since someone could pull up on
the oak without pulling up on the poplar, I need to make sure they are
Thanks for the info. I am going to look at the pdf now.
I built a butternut table (http://www.frontiernet.net/~toller/table.doc )
that had oak for all the internals for strength. The two were glued up
directly. I was warned by more experienced woodworkers that the two would
blow apart. It is now 3 years old, and nothing has happened.
I think that with modern climate, and modern glues, control wood movement
just isn't the issue it used to be.
Frankly though, I am not sure it ever was. I mean, the joints are only a
half inch wide; how much differential expansion can occur over a half inch?
Interestingly, I made a bowl of wenge and ebony. I thought the ebony was
dry, but it wasn't, so over a couple weeks the ebony shrank noticably; but
the glue (polyurethane) crept rather than breaking. I sanded the top down
to make the two surfaces even and no one would notice my screw up.
So, even if there was major differential expansion, the glue might be able
to accomodate it.
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