Tools and Materials Required:
- Boards milled to the same thickness
- 1/8 inch steel plate
- C.N.C. or handheld plasma cutter
- C.N.C. wood router
- Oxy-Acetylene torch
- Table saw
- Router table
- Deadblow or rubber mallet
- Ball peen hammer
- Slag hammer
Step 1: Cutting the Ties
Load the steel plate onto the plasma cutter. For 1/8 inch plate, set the plasma cutter for 40 amps and run it at about 65 inches per minute. Once finished, remove the ties with a pair of pliers (they'll be very hot) and remove any slag buildup on the back with a hammer. An angle grinder with a flap disk can also be utilized for this purpose as well as adding a finish to the steel.
Step 2: Prepping the Boards and Cutting the Inlay
The inlay can be cut by hand, but TechShop Menlo Park's C.N.C. ShopBot wood router was used to preserve accuracy. The inlay should be cut to just over the dimensions of the tie. If the tie was cut using the C.N.C. plasma cutter, the same file can be used for both machines, as the kerf of the plasma will allow the tie to be inset. The slots where the steel will be bent through the wood should be cut wider than the thickness of the metal (approximately 0.010 inches wider).
Affix the boards to the machine table of the C.N.C. wood router with screws, making sure the rabbet joint is pulled tight. If using this method, it is recommended that the boards are cut wider than the final dimensions so that the screw holes can be removed on the table saw when final dimensioning takes place. Cut the inlay, and remove any tear out with 150 grit sandpaper.
Step 3: Bending and Inserting the Tie
Place the boards on a even surface, and slightly clamp them together to prevent the joint from spreading. Use a deadblow mallet to tap the bends into the grooves cut in the wood. Turn the assembly over, and, placing a scrap board over the joint, hammer the boards onto the tie. Be sure to hammer evenly across the seam to prevent the wood from splitting.
Step 4: Wrapping the Tie
Keep a bucket of water handy and bend one strap at a time. Pour water on the wood around the strap to be bent, and heat the steel evenly in a small section. The steel need only be hot enough to bend. The wood will ignite around the steel and char. Again, the bigger the flame, the more the charring will be minimized. Remove the torch from the material to keep the flames down, but do not use water to put out the flame. Once the metal is heated, hit the strap with a ball peen hammer, until it is bent at about 90 degrees. Keep heat on the material as you bend it, After the steel touches the wood, quench immediately with water to pull the joint tight. Repeat the process until all remaining straps are finished.