Stupidity to report . . . with a question

[John Schreiber]

I'm building a Roubo style workbench a la Christopher Schwarz. Most recently I've been laminating 4" wide pieces of 5/4 SYP to make the 90" long top. After rough cleanup with a power jointer, I planed them flat and square with a jack and a jointer, checking them with my trusty tri-square. I check the square regularly by flipping it and it has been as square as I can measure.

Unfortunately, while it is square, the blade has a bit of a curve in it's narrow axis. That means that as I've tilted the blade to look at how the light shows between it and the wood, I've made each piece slightly curved. Like this: You can see the curve by comparing the top line with the straight dotted pink line.

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Measuring across the top and bottom, they are each about 1/32nd narrower than across the middle. I realized this after most of it was already glued. The glue lines are tight now, but I don't know if they will stay tight.

Should I cry?

[Frank Drew]

John,

If the glueup is holding, with no obvious cracks top or bottom, you must not have planed too much of a belly in the boards (if I've understood your description).

Time will tell, of course; inherent stresses in a glue joint usually make themselves known.

[Wilbur Pan]

If I am reading this right, and the curved surface is where you applied glue for the lamination, you might have an issue over the long run. But I bet that other things will be just as important, if not more, such as the grain direction in each piece, and whether you have a curve along the long direction on that face.

One thing that might help is the fact that you are doing a Roubo style bench. If you are going to mortise the legs into the underside of the top, the frame of the base might help minimize any movement that would weaken the glue joint. So would a slight splay to the legs.

[mike holden]

John,
Consider this, David Charlesworth, recommends creating a "belly" in butt joints.
This is exactly what you have done.
Hmmm, dont think I would worry about it.
BUT!!!----I WOULD get a new square! and check it thoroughly.
Mike