I want to make a table top from some oak planks that I have. The oak is about 1" x 6" x 8' each. Is using pocket holes and glue an appropriate method for edge-joining the planks together to make the table top? The other option I have is using biscuits. I'm leaning towards the pocket holes so I won't have to deal with all the clamping that would be needed.
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2 Answers
For strength, a good glue bond is all you need. If you want to minimize clamping, you could use pocket screws, but I would recommend against it. When you tighten a pocket screw, it tends to pull the boards slightly out of alignment unless you first have the boards well clamped, and if you already have them clamped, why bother with the pocket hole screws?
You could use biscuits or dowels (or dominos) to aid in the alignment, but none of those will replace clamping. I find it is really fastest, and easiest to just glue and clamp. You can do the glue up in stages to make things easier - glue up groups of two or three boards, then after they are dry, glue the groups together.
Much useful related info in these previous Questions:
What is a good way to prevent jointed tabletops from bowing when tightening fasteners or the glue sets?
Do pocket hole screws allow for proper expansion and contraction in planked table tops?
Pocket screws are a fast-and-dirty way of joining wood. Where speed is of the essence or clamp numbers are limited what they allow is for clamped-up glued wood joints to have the clamps released as soon as the screws are driven home, since they then act as clamps to keep the joint closed while the glue sets.
I'm leaning towards the pocket holes so I won't have to deal with all the clamping that would be needed.
As you can see from the above there's a problem with the idea that using the pocket screws will save a lot of time here, since to do a good job the tabletop should be clamped up well before the screws are driven home, and if it's clamped anyway why use the screws at all? After all they provide little added strength, and if the joints are done properly no added strength is needed since the joints are at least as strong as the wood around them*.
Re. biscuits, in case you don't know, when jointing tabletops their primary role is as alignment aids during construction, they don't add the strength that people often believe they do. In fact the more you add the weaker the joint can become (still very strong, but weaker than a continuous long-grain joint which is the strongest of all glue joints).
There's another reason to possibly want to avoid using biscuits for this type of joinery work and that is "telegraphing", where the positions of biscuits can become visible on the finished panel as localised raised or sunken areas. 1" material isn't that thin that you should really have to worry about this but ideally you'd want to centre the biscuits in the thickness if that's possible. If not, they should be closer to what will be the bottom of the tabletop, not the top face.
*Some woodworkers using pocket holes when making glued-up panels actually withdraw the screws later because they serve no useful purpose once the glue has cured. And of course this allows the screws to be re-used elsewhere :-)
