<March 15, 2007>
Bellcrank Bushings & Pushrods
Tonight I spent some time reaming out the aileron bellcrank bushings and working on the small aileron pushrods.
I've seen questions posted where builder's ask what is the best way to ream out the aileron bellcrank bushings. Some people will clamp the bushing in a vise and ream it out with a drill bit, but that solution was far to simple for me and I felt I could complicate things a bit. First, using the drill press I drilled a hole in some scrap wood that was roughly equivalent to the OD of the bushing. It was important to use the drill press to drill the hole, as the hole needs to be properly aligned for future steps. Once the hole was drilled, I cut the piece of wood in two bisecting the hole I just drilled.
Next, I clamped the bushing between the two pieces of wood and set them on the drill press table. I then inserted a drill bit that was equivalent to the ID of the bushing and turned down the drill press so that the bit entered the hole in the bushing (while the drill press was off). With the bit inside the bushing, I clamped the entire assembly down to the table, releasing the handle and removing the bit only after I was satisfied that the assembly was centered on the bit (or axis of the drill press).
I then chucked my 1/4" reamer into the drill press and as long as nothing had moved, it was exactly centered on the bushing. Using low RPMs (<350) and a little Boelube I reamed out the bushing.
Perfection! For both bushings, the entire process took less than 30 minutes. It wasn't as complicated as I had thought it would be.
I discovered that the bushing for the left bellcrank wouldn't fit into the bellcrank without binding, so I chucked it into the drill press and turned it down ever so slightly with some sandpaper and Scotchbrite. The bushing are supposed to be 1/64"-1/32" longer than the bellcrank tubes, so I then sanded down the ends of the bushings slightly to achieve the desired length.
I put the bolt and nut in place (by hand) just to hold the parts together until I was ready to install them.
I was really unhappy with the condition of the powdercoat on the small pushrods. Not only had gotten chipped and scratched during the cutting and drilling process, but it was of poor quality to begin with. I thought about just touching it up with the powdercoat touch-up I got from Van's, but there were just too many scrapes and dings. Rather than scuffing the powdercoat and priming or painting on to of it, I decided to sand all of the powdercoat off and apply a fresh coat of self-etching primer. I may apply a coat of spray enamel to seal these off completely.