Building a table
For me, one of the main challenges to building a table is making a sturdy joint between the legs
and the frame, while still making it possible to take the table apart for moving.
The obvious and sturdiest choice would be to just use mortise and tenon join the rails (or apron) and the legs together, but that sort of arrangement can't be taken apart for moving. For most commercial wooden tables, the apron rails aren't really joined to the legs. Instead, a diagonal piece is mounted between the rails, and a single large bolt that pulls the legs in against the rails, pulling the leg against the apron rails.
With the screw tightened, this makes for a reasonably sturdy joint, although it always bothers me
to have the leg attached by just a single bolt. There also isn't a good way for
the vertical load to be transferred from the apron rails to the legs.
I keep thinking, what if you wanted to stand a baby elephant on a table constructed like that?
Surely, it would fail.
Even so, I did try to join legs to a table like that once. But the problem is, this approach does require
holes to be drilled at a 45 degree angle in wood, and to do so very accurately. This is very difficult
to do, even with a drill press. The drill simply pulls to the side too much
when it enters the wood, and even once in the wood, the direction of the grain just pulls it off to the side.
With the holes not quite accurate, the whole thing just doesn't line up properly. So the main reason for not doing it this way is frustration. If you do opt for this approach, I'd recommend getting leg brace hardware - essentially a metal bracket that replaces the piece of wood at a 45 degree angle. Lee Valley Tools sells these.
Nonetheless, I didn't feel like buying these brackets, and I wanted something sturdier anyway.
The approach I have used for several tables now is to join the legs on the end to each other with mortise
and tenon joints, and attach these to the rails that run along the length of the table with stub of wood
that is also mortised into the legs, but screwed to the rails.
for added strength, I join some pieces of doweling into the ends of the rails, which help with alignment and transfer load (ok, this isn't really necessary, but it will help withstand my imagined baby elephant standing on the table).
For the table I was building for this article, I used some table legs I had scrounged from some discarded library furniture. These were made of black walnut. My original idea was to actually dowel the legs with the rails, just to see how well this could be done if one did not have a mortising machine. Plus, I could use my clever horizontal boring jig idea.
Unfortunately, even with the horizontal boring jig, the holes I drilled in the ends of the rail ended up
being at just a little bit of an angle. The problem was that my horizontal boring jig, and even the drill
I use with it, just don't have the rigidity to force the drill to go straight, especially if the drill
on its own likes to wander. I had other drills that had less of a tendency to wander, but these would have
taken a lot more force to drill into the end grain.
So that was a bit of setback. I didn't have another two pieces of wood handy for just re-drilling the holes more carefully. After some thought, I just cut a mortise with my mortising machine where the holes were drilled in both pieces, and join the apron to the leg with a loose tenon.
My home made mortising machine does have the rigidity needed for this job, so I could just cut through the partially crooked holes. Really, I should just cut mortises in both pieces more often, especially for cases where the piece I need to cut the tenon on is too long, so that it would hit the ceeling if I put it in my tenon jig.
Having recovered from the crooked holes, I went on to make the short pieces of wood that the rails that run along the length of the table are screwed into. The tenon for the short pieces only has a shoulder on one side, because it doesn't show, so it didn't matter so much how it looks.
Next I put pegs in the ends of the rails, to mate with the holes I had drilled in the legs. These
are there to align the ends of the rails as well as to transfer vertical load onto the legs
(again, thinking of the imaginary baby elephant).
Tapering the legs
I wanted this table to have tapered legs, so before attaching anything to the legs, I had to do
the tapering.
I prefer to do this sort of work on a jointer. First I mark the final size on the bottom
end of the leg, and then, using a space at the head end under the piece of wood,
I make successive cuts (starting after the spacer, to taper the leg. The space thickness
is picked such that the top of the leg does not get tapered. The taper must not extend
all the way to the top, or the joint surface would also be tapered, which would result in the
legs going on crooked.
The image at right shows the where the spacer is, and gives an idea of how to figure out how
large the spacer needs to be made to have the taper start at the right point.
Its easier to do by holding a ruler to the table leg than it is to use a calculator.
The next step was to glue the mortise and tenon joints. Basically, these formed two assemblies, one for each end of the table, with two legs attached with a rail, and two short pieces of wood sticking out to attach the other rails to.
I subsequently assembled it with the rails, and drilled the screw holes. I clamped the long rails to the assemblies as shown above to make sure the rails were securely pushed into the legs. I didn't have clamps long enough to just clamp end to end, so I clamped a small block to the rails, and then clamped to that block to push the rail into the leg. This limited the amount of force I could apply with the longer clamp, but I didn't need that much force, just enough to make sure it was securely in while I drilled the screw holes.
The assembly, when screwed together looked like this:
And a last step was to glue a piece of wood on the inside of the end pieces to allow screwing the table top to the end pieces. I drilled a total of 6 holes for this, so I could hold the top in such a way to prevent it from warping over time.
I also drilled the holes to be larger on the side on the side where they screw into the table top, so as to give the table top more latitude in terms shrinking and expanding from moisture changes. This is important for a table top made of solid wood (as opposed to plywood or particle board), as it will change dimensions by several millimeters across the width of the table in the cross-grain direction as the humidity changes with the seasons.
For the table top, any sane person would just laminate several planks side to side. However, wanting something fancy I could make from scrap wood, I went on to make this crazily labour intensive Wood tiled table top.
The resulting table, with the black walnut legs, birch apron, and mahogany and birch table top does have a very distinctive kind of look. I'm especially pleased with how the black walnut came out looking with the varnish on it, considering its gray-ish appearance unfinished.
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Related pages:
To my Woodworking website,
or the Woodwork projects page.
