Initial Prep (Debur, Trim, Drill, and Cut)
7/23/23 - 0.3h
7/24/23 - 0.2h
7/28/23 - 0.3h
7/29/23 - 0.5h
8/9/23 - 3.3h
8/10/23 - 0.3h
8/16/23 - 2.0h
8/29/23 - 1.3h
9/18/23 – 2.4h
The Bellcrank-to-Aileron pushrods are made from 1/2” outside diameter powder-coated steel tubing with threaded rod ends riveted to each end. I measured and cut the rods to length just like the larger pushrods in the previous step with a tube cutter. I deburred the cut ends, and then used a bench grinder with a Scotch Brite wheel to get the rod ends to fit.

Drilling the rivet holes in the rods, and match drilling the holes in the rod ends was extremely difficult. I went through three sets of rods before I finally got an acceptable result with the drilling. The first issue is finding the absolute dead center of the rod, and then drilling perpendicular through that spot. The other issue is the slippery finish of the powder coat and the hard steel tube to drill through.

My plan on the first attempt was to use a drill press to drill each of the pilot holes individually, insert the threaded rod ends, and then final drill the holes as specified in the plans. The problem here was the pilot holes were not exactly aligned, so when the holes were match drilled the exit hole didn't hit the pilot hole on the opposite side. Time to trash two sets of rods and ends, and order new parts.

I used a much higher quality drill press on the second attempt, and planned to drill the pilot holes all the way through the tube to keep the holes on the opposite sides perfectly aligned. I failed to consider, however, that the drill bit will go off course due to the small diameter hard steel rod with a slippery powder-coated finish. I went wrong by trying to eyeball the center of the tube, and the very slight misalignment in this attempt meant the rivet holes did not go straight across the axis of the rod, but veered off to the sides. Time to trash two more sets of rods, and order new parts.

I ordered material for two complete sets of rods for my third (and potentially fourth) attempt at this step. Once again, I cut the rods to length, deburred everything, and went back to the drill press. The drill press I used was actually a milling machine with the table connected to a computer that could provide measurements to the 1/10,000th of an inch in the X, Y, and Z directions. The owner of the mill and I had never tried the computer function before, but with parts for 2 tries it was worth an experiment to see if we could make it work. I used a wobble bit in the drill to find one edge of the rod, and set that Z location to zero. I then repeated the process on the other side of the rod to find the width of the rod. Finally, I divided the number on the screen in half, and cranked the Z control to that location. Bingo! Now I'm on the dead-center of the rod! I had previously marked the X distances (6/32” and 13/32”) from the end of each rod for the hole center, so it was a simple matter of aligning the drill with those markings to make the holes. I started drilling the #40 pilot holes by lightly touching the bit to the rod to remove the powder coat finish. I then went slowly through both sides of the rod to get straight holes aligned with each other down the axis of the rod. The next step was to swap out the drill bit for a #30 bit without moving the rod, inserting a threaded rod end and holding it tight in place, and then final drilling the rod and threaded rod end. The result was a clean, straight hole aligned with the axis, that I could immediately drop a rivet into without any resistance. I left the rivet (unset) in the first hole to keep the threaded rod end aligned, rotated the rod 90 degrees, aligned the bit with the new X-location, and drilled the second hole on the first rod end. I repeated the process for the other three rod ends (two rods with two ends each), with good results on each. The computer-aided center measurement on the milling machine made all the difference!

After getting all of the holes drilled, I deburred the holes in the rod and the threaded rod ends to complete the initial parts preparation.
[Hole and Edge Deburring Tools, Tubing Cutter, Ruler, Bench Grinder, 6” Scotch Brite Wheel, #40 Drill, #30 Drill, Drill Press, Computer-Aided Milling Machine]

Prime
9/19/23 – 1.0h
I primed the insides of each of the rods similar to the process for the previous set of control rods. I also primed the threaded rod ends where I had re-sized them to fit in the rods and removed the alodined finish in the process.
[Grey Scotchbrite Pads, Bon-Ami Cleanser, Dupli-Color Degreaser, Rust-Oleum Automotive Self Etching Primer (Green – Rattle Can)]

Assemble
9/20/23 – 1.2h
The trick to final assembly was working with the very long rivets used to attach the threaded rod ends to the pushrods. The plans not that, “These rivets can be difficult to set without them leaning over. Use a hand squeezer to squeeze them a little at a time. If the rivet begins to lean over, adjust the position of the rivet in the squeezer dies to oppose the leaning tendency.” I found the note to be very helpful as the long rivets do tend to lean while they are being squeezed. I went slow with a hand squeezer, adjusted as needed, and came out with decent and acceptable (not perfect) rivets. I did have one rivet that got away from me when my clamping system failed and the part moved dramatically in mid squeeze. I had to drill that one out and set a new rivet, which was successful.

The final step was to thread the rod end bearings and jam nuts onto the threaded rod ends to arrive at the 25 1/4" length between the centers of the bearings. I will wait to tighten the jam nuts until after the aileron rigging is complete so that I can adjust the lengths as needed to establish the neutral position for all of the push rods in the aileron control system.
[Hand Rivet Squeezer, 3/8” Cupped Squeezer Die]