Introduction: Hairpinned Table
The hairpin leg was designed by Henry Glass in 1941 for American Way furniture. A simple "V" of steel rod was connected to a flat "L" bracket, cocked at a slight angle. Hairpin legs produced maximal strength out of minimal material and were easy to make, both ideal qualities during wartime shortages. The visual language -- dematerialized and unadorned -- was picked up by a subsequent generation of designers. Tacked onto any handy flat surface, they've become a shorthand for mid-century modernism.
For this dining table, the hairpins are reversed, angling inwards to brace swept-back legs. Instead of a conventional boxed-out apron, the substructure is an elongated "X", making a slim, elongated profile. The top is made of wide laminated planks, with a chamfered edge and through-tenons in each corner. It seats 8 easily, and 12 in a pinch, but doesn't overwhelm the room.
I used reclaimed Douglas Fir, salvaged from the boiler room of a vacant building. The 12" hairpin legs came from a website (there are a couple specializing in hairpins) and cost about a dollar per inch. Consumables, like glue, lacquer, and resin, brought the total materials budget to about $100. It took between 70-80 hours to make.
Lacking my own shop, I was able to do a lot of the work at the Station North Tool Library, a non-profit public workshop that has open hours twice a week. These sorts of spaces are cropping up all over the world, and are perfect for nomadic makers like myself. They are also proof that you don't have to own all the fanciest woodworking equipment in the world to make your project.
You will need these tools:
- Table saw
- Thickness planer
- Circular saw
- Belt sander
- Orbital sander
- Tape measure
- Adjustable square
- Putty knives
- Block plane
You will need these materials:
- Around 45 linear feet of reclaimed 2x10 material or similar
- 4 12" hairpin legs
- 1-1/4" drywall screws
- Wood glue
- Two-part resin epoxy suitable for filling knots
Step 1: Milling
The lumber I found had sat in the boiler room of a semi-vacant building for about sixty years, judging by the dates on some of the lumber stamps. It was long planks, and I think it was probably used as scaffolding walk boards.
Underneath all that grime and heating oil was beautiful, streaky, reddish Douglas Fir. Whatever lumber you end up using the process is roughly the same. To clean it up, cut it into 8' lengths, then run it through the thickness planer until it is a uniform 1-1/4" thick.
Then use a table saw to cut 1/4" off one edge, flip the board, and do the other edge. Repeat, flipping each time, until they are a uniform 7" wide.
Note: this is not the classic proper method for producing square and straight boards, which involves many passes with a jointer. However, with factory milled lumber that is already surfaced (however years ago that may have been), dry, and relatively straight, I find this method to be much faster and just as effective.
Step 2: Laminating
Lay out all the boards side-by-side on a workbench on top of cauls (T-shaped supports made from 2x4s that keep the surface elevated for clamping). Puzzle the boards around until they fit reasonably well together when pressed by hand, and have alternating end grain -- on one board the grain should "smile," on the next it should "frown," and so forth. When you are happy with the arrangement of the boards, use two pipe clamps to lightly dry fit them, and see if there are any gaps. The boards should close tight to one another with a minimum of pressure.
Use a drywall T-square or straight edge to run a line across all the boards about every 10". Mark the boards A, B, C, and so on. Use a plate (biscuit) joiner to make slots at each mark. Insert biscuits on one side of each board with a dab of wood glue, then brush the running edges of the boards with a thin, even, coat of wood glue. Clamp together, using a mallet to persuade the boards when mis-aligned. Start at one end and work towards the other, using wood scraps to protect the edges of the future surface. Alternate the clamps above and below the assembly to prevent cupping.
Should the assembly begin cupping, clamp a 2x4 crossways to the table to flatten it out.
Step 3: Trimming and Filling
Square the ends of the table by clamping down a straightedge -- in this case a level -- and running a circular saw with a finishing blade across the ends. Remember to keep to offset the measurement by the distance from the edge of the base plate to the face of the blade.
Fill any knots, flaws, or cracks with epoxy. I used this product, which is a simple two-part, 1:1 formulation that dried clear and super-hard. For knots or holes that go all the way through the surface, cover the bottom with painter's or packing tape, then push epoxy into the flaw from above. Add in layers, poking with a toothpick or similar to release any trapped air bubbles.
Step 4: Mortising
Flip the table over. You will need to make 4 recesses so the hairpin legs will mount flush to the underside, and four mortises for the legs themselves. The placement of these two things will vary based on the dimensions of the particular hairpin that you order.
First, get a scrap of 1/2" plywood. Trace out the L-shaped portion of the hairpin onto the plywood, then cut out with a drill and a jigsaw. Clamp it down to a scrap piece of wood and use a router with a top-bearing bit to cut a 1/4" deep test groove. Once the router is properly calibrated, clamp it onto one corner of the table, so that the ends of the "L" are each 3" in from each edge and square to each side. The elbow of the "L" should point towards the center of the table. Rout the recess. Repeat in each corner. Clean out the corners with a chisel as necessary.
Draw a line from each corner of the table through the elbow of the "L" towards the center of the table. These lines should be at a 45-degree angle from the sides of the table, bisecting the 90-degree angle in each corner. Along that line, measure 2-1/4" from the outside corner of the elbow. This will be the start point of the leg mortise. Lay out a 1-1/4" square, with the angled line as its centerline.
Make a second jig from 1/2" plywood that is 1-1/4" by 1-1/4". Use a drill and a jigsaw to cut out the majority of each mortise, staying inside the lines. Put painter's tape on the underside (the future topside) to prevent tearout. Use the router and the jig to take the mortise to its final dimension. Clean up with a chisel.
Step 5: Legs
To make the legs, use a scrap 2x6 as a template leg. Cut parallel 8-degree miters on each end of a 36" blank with a chop saw. Then cut a taper from full width at one end to 1-1/2" at the other. Cut a rough tenon, 1-1/4" long by 2" wide, 2-1/2" from the tapered edge. The factory edge of the leg should face the center of the table. Shave it down to 1-1/4" thick with a chisel or a block plane so it will fit into the mortise. Tap it in with a mallet, then dry-fit a hairpin leg. Strike a line with a straightedge off of the hairpin to transfer the angle onto the leg. Use that line to make a 90-degree notch in the leg that accepts the hairpin.
THIS WILL TAKE SOME TRIAL-AND-ERROR. It tested my patience, for sure; it may take many tries to get the notch for the hairpin calibrated. Once the leg fits, and accepts the hairpin correctly, cut four Douglas Fir blanks at 5-1/2" wide and 36" long, with parallel 8-degree miters. Use a bandsaw to taper each one, and a jointer to flatten out the bandsaw cuts. Bandsaw out the tenon and the hairpin notch.
Step 6: Crossbar Installation
Instead of a traditional apron -- a box-like arrangement of boards on the underside of a table -- I went with a sleeker, lighter elongated "X" substructure. This is more visually coherent, but is more difficult to put together.
Start by cutting a 3"-wide strip of 2-by material to 6' long. If you are lacking a table saw, clamp down a straight edge as a guide for a circular saw as shown in the first picture. The mortise layout lines that extend from each corner of the table towards the center at 45 degrees should cross at the longitudinal centerline of the table. Measure from intersection to intersection and cut the crossbar to that length, with opposing 45-degree miters on each end.
While not strictly necessary, I routed the crossbar into the underside of the table for extra strength. To do this, clamp down two straight edges that trap the router base plate side-to-side and run a groove as wide as the crossbar. Finish the ends with a chisel. Glue and screw in from the top side, countersinking with 3/8" holes to be plugged later.
Step 7: Finishing Up
With the crossbar in place, the legs can be permanently attached. Screw the hairpin leg into place without tightening the screws quite all the way. Coat the tenon of the leg with glue and tap into place with a mallet. Once both are well seated, tighten the screws in the hairpin leg bracket and secure to the wooden leg with a fencing staple. Fill any gaps in the mortise-and-tenon with leftover epoxy. Repeat for each leg.
The legs are linked the crossbar with a sloping brace piece. Start with a 5"-wide piece of 1-1/4"-thick material. Scribe the angle of the leg and cut on the chop saw. Set the cut end against the leg and scribe the other end where it hits the crossbar. Cut at a 45-degree angle so it meets the end of the crossbar. Dry-fit to make sure the length is correct. Taper the piece from 5" at the leg end to the height of the crossbar on the other end with a bandsaw or jigsaw. Repeat for the other three legs.
Glue and screw the four brace pieces in. Toe-screw one end into the leg and one end into the crossbar, with two screws in between into the table top. Counter-sink and plug the screw holes.
Sand the entire table thoroughly, ascending from 80-100-150-220 grits. I used a clear, UV-durable lacquer for a finish, putting down three coats followed by two coats of hard paste wax.
Sit down and enjoy!