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I'm working on building a table, and I'm trying to find some lumber to use for the legs. I've found some 3" x 3" x 3' lumber nearby, which is more or less exactly what I need, however it's relatively expensive.

By that I mean, it's about twice as expensive (per board foot) compared to buying several 1" x 3" boards.

My question is, is there some method of joining three 1" x 3" boards together (I am aware that this will give me a 2.25" x 2.5" result, instead of the 2.5" x 2.5" or a nominally 3" x 3" piece of lumber, but this is acceptable) such that they will be sufficiently strong for the legs of a table (assuming I am going to taper them)?

Or, should I just go ahead and buy the more expensive solid pieces of wood?

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1 Answer 1

up vote 3 down vote accepted

There is a way to create such a composite timber. Actually, all other things being equal (the species, cut and quality of the wood), a built up sandwich is actually stronger than a solid piece of wood.

This is done by laminating the three boards together. A generous layer of wood glue, such as Titebond II, is spread over one face of one of the boards. The next board is placed over this and a second spread of glue is placed on the face of board 2. Finally board three is placed on top.

The boards are aligned and clamped in numerous places along their length. If you are able to clamp them to a very firm perfectly flat surface (such as the platform of a table saw) even better. You need to make sure that there is no bow or twist in the clamped boards.

Once the glue dries (at least 24 hours) you can then trim the ends.

The newel post on the stair rail shown in this question and answer is made up from 3 1x3 oak boards laminated in the manner described.

Unless the table will bear an extremely heavy load or the taper is very extreme (or the wood you are using is balsa), a laminated 2.5 inch leg should be more than sufficient.

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The taper I am thinking of is quite slight, say 2 or 3 degrees (depending on height - e.g., tapering the leg's thickness from 2.5" at the top to 1.5" at the bottom, on the two "inside" sides of the leg). I think I may go with this laminating method, since it's cheaper and I believe you're right - it'll be strong enough (particularly since I'm using oak instead of a softer wood). –  CmdrMoozy Jan 13 at 23:03
    
@bib, question: does grain make a difference in laminating for long boards such as in this application? Regular plywood has alternating grain, and that prompted my question. –  alt Jan 14 at 16:01
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@alt You are right that cross grain lamination gives more stability in the two directions in which the grains cross. That makes plywood more stable in length and width. But for long narrow boards, shifts across the widths are not generally an issue, and the strength of the long grain is more important than any small lateral shift. Furniture grade plywood is often made up of a core of narrow square cut strips that are rotated 90 degrees on their axis to get some of that grain shift stability. In the project described, this should not matter. –  bib Jan 14 at 16:12
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I would say you should affirmatively not laminate with perpendicular grains if the boards are 1" nominal thickness. Plywood is so stable because the glue force from the many laminations are stronger than the expansion/contraction forces of the thin veneers of wood, but at 1" board thickness you'll have considerable wood expansion force (particularly for the layer whose grain is perpendicular to the long dimension) but only 2 glue joins to resist the movement. It will surely split in 6 months when the temperature and humidity change. 3 courses glued parallel will be extremely strong. –  Henry Jackson Jan 14 at 17:58

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