Monday, September 29, 2014

Fabricating The F-1264 Pushrods & F-1265

Prior to priming the canopy frame there are a few parts that require fabrication which I would like primed as well. First up, the F-1264 control stick pushrods which are fabricated from AT6-058x5/16 tubing.
Using the band saw to cut one of the F-1264 control stick pushrods.

Fellow RV-12 builders take note: After cutting the pushrods per the plans and deburring, discovered section 32-04 step 4 of the instructions omitted the information necessary to drill and tap the tubing. Older versions of the plans call for using a #3 drill and tapping 1/4 - 28 threads … but my “updated” version of the drawing was missing that information. Thanks to Joe in Michigan for chiming in on the forums saving me from needing to wait until late Monday morning to call Van’s. It sure would have been far easier using a lathe to drill out the F-1264 control stick pushrods … however, not owning a lathe, had to Jerry-rig a jig to hold the tubing from V blocks and used the drill press to drill the holes.
Drilling the control stick pushrods on the drill press using a #3 drill bit in preparation for tapping the ends of the pushrods.

After drilling out the ends of the F-1264 control stick pushrods using a #3 drill bit, the ends require tapping. A tap with 1/4- 28 threads is then used to thread the ends of the pushrods.
Tapping the F-1264 control stick pushrods for 1/4- 28 threads.
Finished F-1264 control stick pushrods - #3 drill bit and 1/4- 28 tap callout can be seen missing from both step 4 and figure 4 of the plans.

The F-1265 flaperon push rods are made from a long tube and required being cut by hand using a hack saw. I measured the tube and there were a few inches extra so a rough cut was made with a hacksaw a little long and then a final trim cut was made using the band saw.
Using a hand hack saw to rough cut the tubing for the F-1264 flaperon push rods.

After the F-1265 flaperon push rods are cut to the proper length, the tubing is marked for four equally spaced holes which will be drilled into the AN490HT11P-SDM 0.634 threaded rod ends. Fellow builders take note: Here is where I created a big mess for myself … after marking the rivet hole locations I used a spring loaded center punch to center punch the hole locations on the tubing for drilling. Apparently the process of center punching the tubing ever so slightly deformed the tube making the insertion of the threaded rod ends by hand impossible. Mind you, the threaded rod ends are a really tight fit to begin with, so would suggest not center punching or at least place the threaded rod ends in the tubing first which may help hold the shape of the tubing.
Tapping the AN490HT11P threaded rod ends into the flaperon pushrod using a small deep socket to protect the threads on the rod ends. A coating of Boelube was used in the hopes the threaded rod ends can be removed for deburring.

After all the threaded rod ends were in place in the two pushrods, four equally spaced holes were drilled at each end of both tubes which will be used to rivet the pieces together.
Drilling the fourth equally spaced #30 rivet holes into the flaperon pushrod/threaded rod end assembly. Clecos were used to keep position but the fit was so tight that nothing would have moved anyway.
Both F-1265flaperon pushrods with holes drilled into the AN490HT11P threaded rod ends.

The big challenge for the next work session will be removing the AN490HT11P threaded rod ends from the flaperon pushrods for deburring without destroying them. Hoping I may get lucky in that the process of drilling reduced some of the pressure in the area where the tubes were center punched … but I know that is being overly optimistic. It is going to be a fight to get the pieces separated.