Table top "ends"

[Greg Guarino]

For now this is just curiosity; I haven't got a specific project in mind.

If you build a table top from solid wood boards and you want to cover the end grain with other (narrower) boards running perpendicular to the "field" boards, how do you fasten the ends?

I think I get that you can't attach them rigidly, but how do you allow for some play without there being obvious play? Tenons on the ends of the main slats with extra length in the mortise on the ends? Then just screwed in on the bottom in oversized holes?

[Leon]

Bread board ends.

Cut a tenon on the ends of the table, The solid bread board end piece has a mortise to fit the tenon on the end of the table top. Typically the end is placed on the table end and 3~5 holes are drilled through the bread board end and through the tenon. Remove the bread board end and elongate all but the center hole on the tenons to allow for table top expansion and contraction. Replace the bread board end and glue dowels in the holes. The center dowel with the tight fit will keep the end centered. The other dowels will keep the end from coming off the table top but will allow expansion and contraction movement.

I can provide a sletchup drawing if that will be helpful.

Seriously though properly sanded the plain end grain does not look bad and is a lot less trouble. With the other you are always going to get movement and at any given time the bread board end is not going to be flush with the side of the table.

[-MIKE-]

I agree. I might add it is very difficult to get any table top with wide boards to NOT split in one or more places. The big fad, now, in restaurant decor is to have these glued up, fat panel tables with the thickly poured epoxy top finish. I have yet to see one that didn't have splits within a year.

There is probably a right way to do it without splits, but these mass producers aren't doing it.

[joeljcarver]

Try this for a starter:

x

Breadboarding is no deep, arcane method ....

[Larry W]

Google "fastening breadboard ends" and you'll find a multitude of ways to do this. The problem is, with a solid wood table top of any significant width, the change in width with humidity & the seasons means that for much of the time the breadboard ends will be either longer or shorter than the width of the table. IMHO it is better to leave the exposed end grain showing. (On a plywood top, this is not an issue, plywood does not expand/contract the way solid wood does, and the breadboard ends or edge banding can be rigidly fastened.)

[joeljcarver]

You can avoid this by making the ends a bit longer than the table's width and rounding over the ends. I've seen this particularly in some Arts and Crafts furniture.

[Greg Guarino]

I've been wondering about this. How does the moisture get in and out of the (finished) wood? Is the finish more permeable that I think it is? Does the amount of movement depend at all on the type and thickness of finish? To take an extreme example, what about those thick resin finishes you sometimes see on bar and restaurant tables?

I'm not arguing here, I'm just curious about the process.

[Leon]

You never get all the moisture out. Atmospheric conditions such a pressure and temperature can cause the wood to move.

Many of the thick resin finishes have some give, they are pliable.

[-MIKE-]

Look underneath those tables. :-)

[Greg Guarino]

Fair enough. But I think there must be more to it than that. If sufficient sealing eliminated the problem, people would do it, wouldn't they?

[-MIKE-]

As other have said, perhaps there is no sealing sufficient enough to stop movement. If there was a top coat that stopped expansion and contraction of wood, we'd surely see raised panel doors that were made without floating panels. We don't.

[Leon]

You are not going to stop movement, a good finish will simply reduce the amount if you spill a glass of water in the joint.

[Greg Guarino]

Again, I would be the last to argue that I know something the rest of you don't. I'm just curious about the *why* of it. The answer, as best I can tell, is that wood finishes simply do not actually seal the wood against moisture entering or escaping.

[Leon]

That and as I stated earlier, everything chances shape with temperature changes. Most wood has a moisture content in the 6~12% range. Finishing the wood does not remove that moisture.

[Greg Guarino]

I was under the impression that the most important factor is the change in moisture content rather than the absolute amount. That's why I wondered why "sealing" the wood doesn't work. Apparently the answer is that "sealing" does not in fact prevent all moisture migration in and out.

[Leon]

Sealing helps to reduce the amount of absorption and drying out but there is still moisture in the wood that will react to temperature change. Not nearly as much but there will always be change and the reason that you must always allow for wood movement.

[Larry W]

Easy enough to test if you want to.

Take a scrap board of the same type of wood you're going to use, finish it the way you're planning, and measure it when dry (maybe heat it at

100 d Far. in an oven or something) then again when it's good and humid. (Maybe keep put it in the bathroom for a few days when you family is taking hot showers) Measure it and scale up for the width of your table.

[Leon]

And take into consideration that the scrap of wood is not going to move enough to cause a problem. A wide table top however could move in excess of 1/8". So multiply the movement measurement accordingly.

[Scott Lurndal]

Comparing movement in a floor, where all the boards are parallel and growth and shrinkage is all in the same direction (across the grain), to a door, where the boards are arranged in a fashion designed to reduce or eliminate movement across with width of the door (the panels may expand/contract within the frame bounded by the rails and the stiles but neither the rails nor the stiles will change in length, thus you won't see any changes at the margins. Apples != Oranges.

scott

[Larry W]

Uh, that's what "scale up" means.