Joy in the machine . . .

Feb 9, cont'd. Time to make the adapters to hold the truss tubes. Take those 3-inch long by 7/8-inch rounds. Bevel one end. Turn the other end to slip fit into the I.D. of the truss tubes. Leave a crisp shoulder for the tubes to butt against (as if the dimensions are going to be that precise). Mill flats on the first end and drill a hole through the flats to attach the adapter to the frames. Drill and tap a hole through the turned diameter for a set screw to lock the truss tubes in place from inside. Chill. Serve with mint. No dimension is particularly critical on these, but try to keep them pretty uniform. In fact, try to keep them pretty and uniform.

Cut one: set the cross-slide to drive the tool at about a 45-degree angle across the work. Bevel the ends of (at least) 16 of the adapter blanks so they can be mounted back to back on the narrow middle frame. Do them all if you just want to be able to reach into a bag and pick one.

Cut two: Turn one end of each adapter to the inside diameter of the tubing. That's one full revolution of the handwheel on the cross-slide plus 20 ticks of the dial (total 90). You can take 10 ticks per cut roughing, finish with a couple of passes at 3-5 ticks. This step takes about five minutes per adapter. While whittling these down, I realized I'd got it in my head that I needed 20, but the real number is 28. Fine, fine, I have 24 blanks and raw material for more.

Cut three: mill flats top and bottom on the unturned end. These permit a screw to hold them firmly to the frames and bring the truss tubes down "into" the instrument to make everything a little more compact and nifty.

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Text & Photos by David Cortner
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