What's more, the legs are removable so the entire thing packs away compactly — you can stuff it in a closet. If you ever need to set up a formal dining table for ten, you just toss the thing in the back of your car and go.
The construction of the table is based on telescoping rails built from a series of hardwood blocks. This is the most interesting and challenging part of the project.
Note: the astute reader may notice occasional differences between the drawings and the photographs. Where there are differences, the drawings should taken as the canonical source. The photos are of a prototype, and the design has been refined since it was built.
The attached Sketchup files include complete designs for the table. The second file is the details of the rail construction.
This file is entered in the furniture design contest; I appreciate your vote.
Step 1: Required Skills, Tools, and Materials.
Eye and ear protection.
At the very least you'll need a table saw, drill, and router table. A power sander and drill press are highly recommended and a biscuit joiner would also come in handy. For the router, you need a dovetail bit, a 5/16" or 3/8" straight bit, and a larger straight bit capable of cutting 3/4" deep, plus any decorative bits you desire for the edges.
A sharp chisel.
A ratchet wrench, extension, and 3/8" deep socket.
Plus the usual straight edges, screwdrivers, clamps and so forth.
Two sheets of ¾" plywood, one side good (I recommend oak).
Hardwood of the same type sufficient to make a ½"x¾" border around the entire table: two 8' lengths, two 4' lengths, and two 2' lengths. If you can't get 8' lengths, don't despair; you'll just need eight 19" lengths.
Hardwood sufficient to make 20 16"x2¼x1¼ blocks. Poplar is good; birch or maple is even better.
Six table legs, 2½" x 2½" at the top, 28" high (more or less, depending on how tall you want your table to be). You can make these or mail-order them, which is what I did. Just search for "wood table legs" and a number of vendors will pop up. Larger table legs will work just fine, but don't go smaller than 2½" x 2½".
Two table leg brackets. Just search for "table leg bracket" and a number of vendors will pop up.
Four ¼"x2½" hanger bolts (available at any hardware store). These are two-ended bolts that have wood screw threads on one end and machine threads on the other. These are screwed into wooden objects and leave protruding threads to allow things to be bolted on.
Four ¼" wing nuts and four washers.
Two 3/8"x3" hanger bolts.
two 3/8" hex nuts and two washers.
Glue, screws, stain, varnish
Step 2: Cutting the Rails
The telescoping rails are the most interesting part, so we'll start there.
(UPDATE: I just found out that you can just buy these. Do a Google search for "extension slide". You can skip this whole step if you want.)
Begin with eighteen wood blocks, 16" x 2¼ x 1¼. Make these as straight and square as you can. Any issues here will prevent the entire system from working. It's probably a good idea to make a couple of spares.
Step 3: Cutting the Dovetail Grooves
To reduce strain on the router and dovetail bit, I like to hog out the bulk of the material on a table saw with a dado blade and then finish the dovetails with a dovetail bit on a router table.
Just in case the groove isn't perfectly centered on the block — and it never is — designate the edge of the block that was up against the router table fence as the top of the rail. Make sure that the grooves on both sides use the same edge as the top. This procedure will ensure that all the blocks are matched with each other.
Finally, repeat the process with the remaining four blocks, but only put the grooves on one side. These will be the front and back rails.
When making the dovetails on the front and back rails, adjust the fence on your router table just a tiny bit away from the router bit -- perhaps 1/32 of an inch. This will have the effect of giving the rails a tiny bit of clearance under the table top. Again, designate the edge against the router table fence as the top.
Step 4: Bevels
Step 5: Rail Pegs
Near one end of each of the fourteen rails, drill a hole to accept a peg (shown in the picture). Don't insert the peg yet.
Make half the rails mirror images of the other half -- that is, put the peg on the right of seven of the rails as shown in the picture, and put the peg on the left of the other seven.
The exact size and position of the peg is up to you, but make sure all rails are identical.
On the opposite side of each rail from the peg, cut a matching slot in the rail. The slot should be slightly over-sized so that the peg from the adjoining rail slides in easily.
The photograph shows a finished rail with its peg and matching slot.
Remember, don't install the pegs yet.
Step 6: Sliders
Make 32 of these as shown in the diagram. They are 2½" long and their cross-section dimensions match the grooves. One half of each slider should be a snug fit into a groove (where it will be glued), and the other half just slightly loose so that is slides easily through the groove of the adjoining rail. I find that a bit of sanding is enough to do the job.
Hint: make half of these sliders just a little bit longer than the others, maybe 1/8". This will make final assembly much easier when the time comes.
Step 7: Cut-away Views
Step 8: Front Rails
The front rails are mounted below the top of the front section of the table. Make two.
This diagram is an X-ray view of one of the two front rails. These will be attached to the top from below with screws. You'll need a drill press or a steady hand with a hand-held drill.
Drill three holes from the bottom, wide enough to clear the heads of the screws, deep enough into the blocks so that the screws will protrude just under 3/4" out of the top.
Drill three holes wide enough to clear the screw shanks the rest of the way through the rails.
The exact hole locations are not critical, but don't intersect the dovetail groove.
Update: If you have a pocket hole jig, you could probably use that instead, but first test to make sure the pocket holes don't intersect the dovetail slots.
Step 9: Rear Rails
The rear rails are attached to the rear section of the table.
This diagram is an X-ray view of the two rear rails. These will be attached to the sides of the table with screws. Again, you need a drill press or a steady hand.
The rear rails should be mirror images of each other.
Drill the holes into the sides of the rail from the groove side, again choosing the depth so that the screws will protrude from the other side of the rails just under ¾".
Stay at least 5" back from the fronts of the rails when drilling the holes, since you will not be able to access the front 5" of the rail at assembly time.
Other than that, position is not critical as long as you don't intersect the dovetail groove.
Also bevel the front end of the two rear rails as shown in the diagram.
Step 10: Assembling the Rails
Glue two sliders into each rail as shown in the diagram. One slider goes below the peg slot, and the other is on the opposite side, opposite end.
Remember that half of your rails are mirror images of the other half.
If you made half of the sliders slightly longer as described above, put the longer slider at the peg slot end.
One slider goes at the back of each front rail, and at the front of each back rail. Again, you're making mirror images here. It might be a good idea to hold off on gluing the sliders into the front and rear rails until you're certain you've got the right ends.
Step 11: Assembling the Rails, Cont.
Apply paste wax or other furniture wax on the faces of the rails and on the sliders so that all moving parts move smoothly against each other.
Join all of the rails together; create two sets of seven. Test them for fit. Make sure the entire assembly moves smoothly.
(If you made half the sliders longer, this process is much easier, since you only half to match the sliders to grooves one end at a time instead of both at once.)
Remove the first and last rails from each assembly; construction will go easier of you assemble them for good later.
Step 12: Constructing the Top
(Note: the cutting diagram in the third photo gives you grain that runs the length of the table. If you want grain that runs side-to-side, you'll need to cut the pieces in a different way.)
You need one full sheet of plywood for this, plus a quarter of the next sheet. You also need hardwood edging sufficient to go all around the edge of the table.
In this step you create the front top (permanently attached to the table) and five leaves. One leaf has a trim piece at the end, and this one is designated the rear leaf.
These plans create a top that's 49 inches wide and 120 inches long (including edging.) This way, the math comes out neatly and it involves fewer cuts, but feel free to change the dimensions to suit your needs.
You can either glue the edging onto the plywood first, and then cut it into leaves, or cut the leaves first and add the edging after. It's up to you, although if you can't make edging pieces as long as your sheet of plywood, you'll probably have to cut the leaves first. I found that attaching the edging first worked better.
I used splines to attach the edging to the plywood to make the joints stronger. See photo. You can probably get away with just gluing them on, or using biscuits.
To make the leaves, put edging along both long edges of the plywood sheet, and along one end. Cut the plywood into five 19" lengths. (The rear leaf will be 19½" long, including the edging.)
For the top, cut a 24-inch length from the second sheet of plywood and put edging on the end and the two edges. See diagram.
Using the decorative router bit of your choice, make the edging more interesting than just a straight rectangle. Sand or plane edging flush with the table top if needed. Now is a good time to sand the top.
Cut each leaf from the plywood sheet 48 inches wide and 19 inches long.
Step 13: Table Pins
[Update: it turns out that you can just buy these rather than sanding down a dowel. Just search for "table pins" on the internet.]
To keep the leaves aligned with each other, one edge of each leaf has a couple of pegs that mate with holes on the next leaf.
The exact location you use for the pegs is up to you, but BE CONSISTENT. Every leaf needs to be able to mate with every other leaf.
If you have a horizontal boring machine, good for you. If not, you can build a jig to guide your hand-held drill bit into the edge. Clamp the jig to the edge of your board where you want to drill the hole, and let the hole in the jig guide your drill bit.
Drill two holes on each edge of every leaf, plus on the non-edging edge of the front top and rear leaf.
Add pegs to one edge of each leaf, including the rear leaf.
It helps if the pegs are slightly pointed as shown in the diagram. The photographs show one way to do this.
Step 14: Building the Front Section
Cut out the three plywood panels as shown in the diagram:
* Front side (A), 16" x 4½". Make 2
* Front front (B), 38" x 4½"
* Short cleat, 7" x ¾" x ½". Make 2
* Long cleat, 12" x ¾" x ½". Make 3. Taper one end of two of them.
If you're going to use cleats to attach the top to the panels, make them as well. The two side cleats should be beveled as shown in the diagram so that they don't catch on the back half of the table when it's slid together. You can avoid cleats by using pocket holes, biscuits, or dowels to join the panel pieces to the top.
Depending on the leg brackets you use, you may need to cut shallow slots into the pieces or make other accommodations.
Assemble as shown in the diagram and photographs. Be sure to attach one sliding rail to each of the front rails before screwing the front rails into place.
Step 15: Constructing the Rear Section
Cut out the four plywood panels as shown in the diagram.
* Rear side (C), 14 5/8" x 4½"
* Rear back (D), 39½" x 4½"
* Rear bottom (E), 38" x 5"
On the two side pieces (C), drill two holes 1½" from the bottom and ¾" from the end. Make the holes large enough for the 3/8" hangar bolts.
Drill two more holes higher up on the sides, large enough to accommodate the alignment pegs you'll be using. I used ½" dowels for strength.
Assemble the back section as shown in the diagram. Biscuit joints are best, but screws, dowels, or cleats are acceptable too. If you use screws, plug the screw holes for best appearance.
Be sure to attach one sliding rail to each of the rear rails before screwing the rear rails into place.
Step 16: The Legs
Modify the six legs as shown in the diagram and photographs.
The front legs may need to be trimmed slightly to make room for the leg brackets. Drill holes for the hangar bolts that came with the brackets and install the hanger bolts.
Drill holes into the legs to receive the hanger bolts. These should be smaller than the diameter of the screw part of the bolts, but large enough so that the wood doesn't split as you drive the hanger bolt in.
I find the easiest way to drive hanger bolts is to thread two nuts with a washer between them onto the bolt. Tighten the nuts together and then use a wrench to drive the outer nut, which will drive the hanger bolt. The two nuts will loosen quite easily when you're done.
The middle legs merely need to be shortened by 2 13/16".
The rear legs need to have a rectangular block of wood removed as shown in the diagrams. I used a router and a chisel for this work.
Place the rear legs on the rear section and test the fit. Drill holes in the rear legs to accommodate the hangar bolt and alignment peg. Transferring the exact locations of these holes from the rear section to the legs can be tricky. Measure precisely, or use dowel center transfer plugs — these can be found cheap from a number of sources.
Install hanger bolts into rear legs. Drill holes into the legs to receive the hanger bolts. These should be smaller than the diameter of the screw part of the bolts, but large enough so that the wood doesn't split as you drive the hanger bolt in.
Taper and sand your alignment pegs so that they fit easily into the holes in the rear section. You may want to test fit a few times before gluing the pegs into the legs.
Attach the rear legs to the rear section by sliding the hanger bolts and pegs into their holes, then securing with a washer and nut from the inside.
When the rear legs are attached to the rear section, it's a tight fit, so you'll want a socket wrench with an extension.
Step 17: Table Assembly
Insert the pins which prevent the rails from coming apart again. Glue them into place if needed. The moving rail segment that mates with the rear rail won't need a peg.
Step 18: Attach Middle Legs
* Leg support (F), 33" x 6"
Glue thin 1/16" spacer strips to the board as shown in the diagram. The strips should align with the middle sliding rails as shown. The spacer strips prevent the other sliding rails from binding as they pass over the board.
Permanently attach the middle legs to the ends of the board. Don't let any screw heads protrude above the board, as sliding rails will have to pass over this point.
Drill four holes through the leg support board and spacing strips large enough to pass the hanger bolts. If you used ¼" hanger bolts, then drill holes slightly larger than ¼".
Drill four holes into the middle sliding rails to receive the hanger bolts. These should be smaller than 1/4" but large enough so that the wood doesn't split as you drive the hanger bolt in.
Assemble the middle legs to the sliding rails with washers and wing nuts.
Step 19: Leaf Cleats
Connect all the leaves, adjust the length of the table, and center the table on the leaves until everything is just the way you want it. Ideally, the rear leaf should extend the same distance beyond the rear section as the top extends beyond the front section.
Attach a couple of small cleats to the rear leaf as shown in the diagram. These serve to keep everything in place when the table is extended.
Step 20: Finishing
Step 21: Storage and Transport
Step 22: Alternative Design
Advantages: a little more stable than the design with just a single top section permanently attached to the table, and you won't need the leaf cleats shown in step 19. Disadvantages: unsightly seam when table is completely closed.