Push Rod

Aileron Bell Crank To Stick Push Rod

After composing myself from mis-cutting the aileron bell crank to aileron push rod, I picked up where I left off on the aileron bell crank to stick push rod and drilled the ends to accommodate the 6 blind rivets used to hold the threaded rod end.  I again used masking tape to mark the location of the 6 holes as follows:

  • The push rod is 1.125" in diameter.  This gives a circumference of 3.53".  When I divided the circumference by 6, each hole was drilled .58" apart.
  • The flange for the threaded rod end will be inserted .5" into the push rod tube.  I placed the rivet holes .25" from the end of the push rod.


Using the spring loaded center punch kept the drill bit from wandering when I started drilling the hole.  Without center punching the hole, I couldn't keep the drill bit properly centered on the curved surface.


I drilled the holes in three stages.  I started drilling with a size #50 drill bit, then drilled to size #40, and finally drilled the holes to size #30.


I clecoed the rod end to the push rod to hold it in place.  The threaded rod end fits fairly snug in the tube, but I didn't want the thing to shift while I was drilling and then an oblong hole or a hole that didn't line up.  It was quick to throw a cleco or two in and it resulted in perfect alignment of all the holes.


Mix up a little epoxy primer and a couple of blind rivets and you have a finished aileron push rod.  I did deviate slightly from the plans in that I used 3 MSP-42 blind rivets and 3 Cherrymax rivets per end.  I have a lot of faith in the strength of a Cherrymax rivet so I figured that using them may add a margin of strength to the riveted connection.  At 50 cents per rivet, I didn't want to fill all 24 holes with Cherrymax rivets.


The aileron bell crank to stick push rods are done for now.  On to the next wing task.

Fabricating Aileron Push Rods

I decided that I would start fabricating the aileron push-pull tubes.  My remaining wing crate is getting fairly empty (finally).  Not everything is fully assembled, but is clecoed so something that is.  I have been told that it is possible to finish the wings.


I started with the shorter, steel tube push-pull rod.  This is the rod that goes from the aileron bell crank to the aileron.  Van's specs state to cut this rod to 23 13/16".  Okay, say it again, Twenty Three Inches and Thirteen Sixteenths..... I got it... lets cut....


What the HE double hockey sticks is this?  The push rod has been cut to 23 13/32".  What is worse is that I didn't notice my error until I started writing up my log entry for aileron push rod.  I wonder if I can apply the man-hours to the re-work that will be required to the 51% rule.  Do you get bonus points for doing 10% of the airplane twice?

Okay, let me take a moment to digress and talk about when you SHOULDN'T build.  Sometimes it is very obvious when you shouldn't build the plan.  Some examples may include: when it conflicts with other family obligations, when you are sick, or after drinking plenty of beer.  Now those seem obvious, but then there are the not so obvious times you shouldn't build.  Some examples of this may include:  When your mind is on other things, you are equally interested in what is currently on the satellite TV channel, and when you want to HURRY up and get this done before you go to bed.  Now you may get by and have one of these things happening while you are building and you may not make a single mistake.  I was not that lucky on this activity.  This was a case when it was not clear that I should maybe put the project down until after a good nights sleep.  Start fresh in the morning.  I know that everyone makes mistakes, but it doesn't make me feel any better, when in retrospect, this was a stupid mistake.

Other than the push rods being 13/32" of an inch short, they turned out perfect.  I knew it was going to smoothly....


To get my two holes setup for the solid rivets that would hold the threaded rod end, I used a piece of masking tape, marked where the edge of the threaded rod end would be and then divided that distance by 3 to equally space the two rivets.


I bought the V-jig when I first started this project, knowing that I would need it for some of the control push rods.  This worked great to hold the push rod in place and centered for the drill press.  I really only needed one vice grip clamp to hold the push rod in place.  The rubber tips that came with the clamps worked great to hold the rod in the jig.


I read were some builders had a hard time getting the holes started as the drill bit wants to 'wander' when you start drilling.  If you haven't gotten yourself an automatic (spring loaded) center punch, buy one now...  They work great and I didn't have any difficulty drilling the push rod holes.


I wish Van's would just sell these welded and powder coated so they looked great.  This solution works, but it isn't the prettiest looking device.  I have also read where some builders had difficulty in setting these rivets.  I did two things based on reading Dave Parsons experience with these rods.

  1. Van's calls out the use of AN470AD4-12 rivets to be used here.  I used a shorter rivet (-11).  These are still pretty long when pushed through the hole.  Even using the -11 rivets, I was concerned about being able to form a shop head without bending the rivet shaft over.
  2. I placed the push rods in a vise to hold them securely while trying to rivet them.
  3. I was able to use my pneumatic squeezer with the no-hole yoke.  This was the only yoke I could get opened far enough to squeeze the -11 rivets. 

With the vice holding the tube and me having some leverage with the squeezer, I was able to squeeze some decent looking rivets.  I touched up and primed the ends with some rattle can self etching primer.  Now if those rods hadn't been cut to SHORT......


I then cut the longer stick to aileron bell crank push rods.  After I learned that I cut the previous push rods to short, I had to go back out and check my measurements on the longer push rods.  My heart skipped a beat when I learned I DID cut those correctly!!!!


I did double check the overall length requirement of those shorter push rods (27 5/8").  I can obtain the overall length required per the print and still have numerous threads engaged in the rod end bearing.  However, I decided that I AM NOT going to compromise here and I have already ordered the replacement parts.  I believe the push rod parts will cost me around $25.  Not worth compromising for that kind of money.