Initial Prep (Debur, Trim, Drill, and Cut)
9/1/23 - 0.6h
9/3/23 - 1.8h
This is my first opportunity to use a tap to cut threads on the inside of a tube. The first step in the fabrication of the autopilot servo pushrods was to cut a couple of pieces of tube to the specified length. The tube cutter did a nice job of making accurate and square cuts to the tubing. I also cut the short (15/32”) stand-off spacer for the roll servo installation since the tube cutter was out and ready.

There was a short piece of tubing left over, so I decided to use that to practice the rest of the fabrication steps starting with drilling out the center of the tube with the #3 droll bit. The #3 bit tracks with the tap guide in my tap and die kit. I wrapped the tube in a layer of duct tape, and then clamped the tube into a bench vise to hold it still and steady. The tape did a good job to keep the outside of the tube from getting damaged by the vise, but it can slip. I found I had to reclamp the tube several times throughout the drill and tap process when it started to slip. My main concern with drilling was drilling straight and center on the tube.

The next step was to tap the tube 1/4-28. I used some cutting fluid on the tube and the tap, and started turning the tap very slowly. The tap does not need a lot of downward force, and the main concern is starting the tap straight with the tube. Once the tap is going, I would complete one turn with the tap, and then back it out two or three turns to help clear the shavings. This process continued until the tap was to the correct depth. After taping the tube, I pushed a couple q-tips through to help clean out the debris from the process. I also pulled a thin cloth with alcohol through the tube to clean it out. The process worked well on the test part, and I was able to repeat that success with the real parts.
[Hole and Edge Deburring Tools, Tube Cutter, #3 Drill, 1/4-28 Tap, Boelube, Tap Cutting Fluid]

Prime
9/3/23 - 0.2h
Priming was similar to other pushrods in the build. I started by priming the interior and ends of the pushrods, and then primed the exterior. I also primed the stand-off spacer.
[Scotch Brite Pads, Dupli-Color Degreaser, Rust-Oleum Automotive Self Etching Primer (Green – Rattle Can)]

Assemble
9/4/23 - 0.1h
Assembly went very quickly after giving the primer the evening to cure. The jam nuts get threaded onto the rod ends, and then the rod ends get threaded into the push rods. The drawings in the plans are scaled 1:1, so it was easy to size the pushrods using the drawings on the page.