Table top glue-up, need advice

[Brian Kincaid]

Getting ready to glue-up a huge walnut kitchen table, but the boards i have prepped have some curve along the length, maybe 1/2" on the ends when place side by side.

The boards are all 1-1/16" thick which I want to maintain. I do not need a workbench-flat table.

I can't really flip over the boards and make the warp go all the same way because the defects and discoloration of the backs would greatly detract from the table.

My thought is to domino the boards every 6" along the glue line so they fight each other. I was able to clamp them together and use hand pressure to straighten them.

Any thoughts on whether this is a good or bad idea? Here's a picture of the resaw since no-pics-didn't-happen.
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-Brian

[scott vroom]

Are the boards bowed or crooked? How long are the boards?

[Paul Symchych]

Without more information it is going to be a guess from the thumbnail photos that the boards are around a foot wide by 5? 6? more? long. If not cupped, twisted etc a 1/2" bow could be handled by inserting a spline the length of the boards. My DR table is walnut, ~6 feet long and thats what I did.

[scott vroom]

If the bow can be pulled out by hand, then cauls can be used to pull the boards together at glue up...you could use a few biscuits if you want, but not necessary to do a full length spline IMO. If it's a table top you should be using cauls anyway to maximize overall flatness across the glue up.

[Brian Kincaid]

Took a sec to look up the terminology, the boards are 'bowed'. They are 82" long. Sounds like the domino/spline has been tried and trued. I'll be using a few cauls for the glue-up, thanks for the reminder Scott.

Sorry for the thumbnails, thought I was attaching full image, but you get the idea :)

-Brian

Bow Distortion of a board lengthwise. A bowed board is no longer flat across its length.
Crook Distortion of a board widthwise. A crooked board is no longer flat across its edge.
Cup Distortion of a board widthwise. A cupped board is no longer flat across its width.
Twist Distortion of a board both lengthwise and/or widthwise. A twisted board is no longer flat across its face.
Warp A collective term for any variation in the flatness of a board. It can include bow, crook, cup and/or twist.

[Terry Beadle]

IMHO the boards should not "fight" it out. Use a Stanley 07 jointer to true the edges. You should be able to lay them edge to edge with no fight involved. 1/2 inch is way too much to expect the joint to last as we all know wood moves in mysterious ways. This comment 'assumes' a bowed edge problem.

If the timbers are having a bow that's due to a cupping or bow in the verticle to the pieces work face, that's a different matter. Bisquits or dowels or slip tenons are the norm to solve that problem. Some times you can rip the pieces to relieve the stress to a narrower piece and just rejoin the pieces back. During glue up, cauls with a slightly curved from center face towards the work pieces will put a lot of pressure vertically so the joints will be strong. That said, it's still a good idea that the work pieces not have to be clamped down vertically to mate a 1/2 inch vertical bow. If the table is to last, you need to get the pieces relieved enough to reduce that stress to less than as 1/4 in IMO. Otherwise, I think that over time the boards will pop/crack/warp etc.

In some cases, you may just have to bite the bullet and buy better stock.

In summary, pieces should never have to fight it out IMO for either case.

Good luck and enjoy the shavings !

[Jeff Duncan]

I can't say whether or not your technique will work, I can say I'd be very concerned trying it. Very generally speaking you want your stock to be as straight and true as possible/practical. The more you have to force it into a position, the more concerned I'd be. Glue and tenons should hold it together, but if one board takes more "force" to get it into place, it may well pull the other boards out of flat.

Just as food for though....when I need to make something flat I buy stock thick enough and straight enough that I can get it flat. If it's too thin or too far out, I pass on it. I just find it much easier than stressing over what's going to happen after I invest a lot of time into building something. And even in those circumstance sometimes things move unexpectedly! I also try to avoid re-sawing thicker parts whenever possible as I find the wood likes to move quite a bit after re-sawing. For thinner stock it's not as much an issue.

good luck,
JeffD