More tabletop travails - a bow

[Tony Wilkins]

Still work8mg on the walnut top for the dining table I’m making. Have the boards laid out after having skip planed them. One of the boards (the third in order so second joint) has developed a bit more of a bow. It’s one of the thinner boards so I’m looking for suggestions how to handle it.
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[Ben Ellenberger]

Are you making a traditional base for the table? Are the rest of the pieces for the top straight?

I’d expect everything to be fine if both of those are true. If the base won’t help hold the top flat, then it seems trickier and more dependent on the pieces you use for the top.

[David Carroll]

Assuming it's at or near the final thickness and you can't plane it flat, I think I would edge joint it (both edges) and clamp it flat on the bench near to the edge, then glue another board to it, clamp it up and leave it to dry/cure thoroughly, I don't often use splines, biscuits or dowels, but this would be one time that I would. Then flip it and repeat to the other edge. Now you have three boards glued up. The neighboring boards sandwiching the bowed one will keep it flat. Then glue up the rest.

These days I use match planes to tongue and groove the edges which holds them in plane while gluing up. but I still usually glue wide panels in sections, rather than all at one time.

DC

[Tony Wilkins]

Are you making a traditional base for the table? Are the rest of the pieces for the top straight?

I’d expect everything to be fine if both of those are true. If the base won’t help hold the top flat, then it seems trickier and more dependent on the pieces you use for the top.

I was planning a trestle base. I believe all the rest are flat but then this one wasn’t so bowed when I put it down.

[Ben Ellenberger]

I was planning a trestle base. I believe all the rest are flat but then this one wasn’t so bowed when I put it down.

I guess that is trickier, since the base won’t help straighten it. It’s hard to tell from pictures, but if the other boards are straight, they may be enough to keep the whole top straight after glue-up. It will make the glue-up harder, but you could use splines, or just glue one joint at a time and use clamp pressure and mallet taps to line everything up.

[Tony Wilkins]

Tangential question: with six boards making up the top, would you glue up all of them at once or in pairs? Or some way else?

[David Carroll]

Tangential question: with six boards making up the top, would you glue up all of them at once or in pairs? Or some way else?

For me it depends on how flat the boards are, how wide the whole panel will be and do I own enough clamps (I don't). Typically, my glue ups are in odd number of boards, so I have a board in the center of the panel and not a seam.

If they're random widths I put the widest in the middle, assuming the grain match works out that way. Then I usually glue up two or three at once, it's more manageable that way, particularly if they're long or not very flat. Then I glue up the two parts as a second operation.

Like I said, I don't a lot of long clamps, so I spring the joint somewhat and focus the clamps on the the center, the ends take care of themselves with a sprung joint. I use hand screws at the ends to keep the ends from creeping.

But there is no right or wrong way. If I had a big assembly table, and 8 or 10 long clamps, I'd likely glue it all up at once. But I don't.

DC

[Jack Dover]

I had exactly the same problem. Was expecting that two boards will straighten a middle one, but the opposite has happened. It was a trestle table too, so I had to use a tabletop stiffener, because a connecting rail was below a knee level, didn't have screws this long. Next time I build a trestle table a connecting rail will be directly under a top, so it can be used to straighten the top.