Here’s a neophyte question for you. I have a 1.75″ maple benchtop to which I want to glue a skirt. As I understand it, the grain of the skirt needs to be oriented the same direction as the benchtop. This would, in this case, imply using a quartersawn 2×6 board for the skirt. I have noticed that it is very difficult to find quartersawn maple in these dimensions, at least locally. I’m leary of purchasing wood I’ve never seen from 2-3000 miles away.
So, I’m left with the choice of using a different wood for the skirt or “faking” a skirt by attaching it to the bench bottom and simply laying the top slab inside the frame made by the skirt.
Is there potential trouble in face-gluing two kinds of wood together? I’m concerned about different rates of relative shrinkage damaging the glue joint or the wood. If this is a valid concern, what kinds of wood could I glue to maple without causing problems? Or, better yet, how could I figure this out for myself?
Thanks,
Mike
Replies
Mike,
For hard maple, the difference in movement between the two grain orientations over a 10% moisture change across a 1.75" glue joint is only .03". The difference isn't enough to crack anything, so the worst that would happen is you might feel a slight misalignment across the joint during some part of the year and that would only happen in a climate with a large swing in relative humidity.
If you want to be able to figure this out for yourself, I highly recommend the "The Wood Movement Reference Guide" sold by Lee Valley, it costs just a few dollars.
Also the entire skirt doesn't need to be quarter sawn, only the portion that is glued to the edge of the top. Many flatsawn boards will have grain running closer to quarter sawn along one edge. Also, you don't have to glue the entire width of the joint, just glue a strip closest to the top surface, if you only had a 3/4" wide glued surface the movement difference would only be .013 under the same conditions as the original calculation.
John White, Shop Manager, Fine Woodworking Magazine
I'm pretty new at woodworking so please, someone, straighten me out. I would think the benchtop to be quarter sawn, so to keep the same direction of grain with the skirt glued to it at 90°, the skirt would need to be plain sawn. Please help.
PAUL
The boards in a benchtop could be either flatsawn or quarter sawn, with the quarter sawn being the better choice, all other things being equal, but a top made from carefully chosen narrower flatsawn boards can be perfectly adequate.
John W.
What about using a polyurethane glue? I would assume that it would have a bit more elasticity than either white glue or epoxy? Magnus
"Remember, a bad carpenter always blames his tools"
Magnus,
For the small amount of movement involved any glue will work well, it isn't worth dealing with the mess that polyurethane creates and standard yellow glue is in fact a bit more flexible than polyurethane.
John W.
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