Fabricating the F-789 Elevator push tube - 2.5 hours

 The last push tube to finish is the F-789 elevator push rod. Again I used Autocad to work out the rivet spacing 

The lines are marked on the tube, and drilled in the drill press. 

The same prime and paint process was used, and by the end of the evening I have the push tube primed and assembled and late evening I was able to spray a couple of coats of final color. 

During the day, a local builder Tracy Trathern who has a beautiful RV-7A dropped by to look in on the project. He also dropped of an ELT that he was selling. So I am now a proud owner of an Artex ELT 345. I will need to figure out how to mount this on my plane. 

More fabrication of the pushrods - 3 hours

 Todays build was not that long. Just the logistics of this particular build, need to finish this aft pushrod in order to finalize the forward elevator pushrod. 

The manual has you confirm correct position of the pushrod in that the bottom bellcrank bolt is entered in the opening (using a socket) when the elevators are perfectly neutral/aligned with the horizontal stabilizer. Once this was set. I made my reference lines, measurements and began cutting the pushrod accordingly. Van’s dimension is extremely close to spot on. 

 

I then could drill the aft end of the pushrod for rivets. Now….priming the inside of that tube was an incredible pain. My quart can of 1K primer that I used on the wing tubes was rock solid cause it sat so long. All I have now is 2K epoxy primer. I mixed up a small amount and dumped it into the tube and worked it back and forth. WOW is that stuff heavy. It’s so thick inside trying to do it this way. Eventually I abandoned this idea and cleaned the entire tube out with MEK and a rag, pushing it through a few times with a long stick.

Instead I used the self etching rattle can primer. Using the included narrow nozzle and spraying down the tube from each end. Not 100% prefect. But at least its not super heavy. 

I could then install the primed ends into the tube and rivet. 

 

Once riveted and a bit more primer. I gave a final paint coat later on in the evening.

Started fabrication of the elevator pushrods - 3 hours

 I need to fabricate the two elevator pushrods. I cheat a bit with figuring out my rivet spacing by drafting what I need in AutoCAD. Drawing the diameter of the pushrods, then getting the circumference. That makes it really easy to print out a piece of paper with the needed rivet dimensions on it. That is then transcribed to the one end of each pushrod and I’m ready to drill.

Now comes the fun part. I want to make sure Van’s dimensions on the control rods are correct before I cut and drill the other end of the pushrods. The only way to do that is to install the rods and then take measurements. I managed to get everything installed and set up for the aft elevator pushrod. Looking good.

 

I’ll call it a night and start in when I’m fresh in the morning.

Finished drilling the elevator horns - 3 hours

After talking to Vans Tech support. I will take some time to move the existing pilot hole I drilled further in. Realistically I can move the pilot hole 1/64" (0.015625"). That would allow a final edge distance of 0.320" on the opposite control horn. 

 I drew a 3/16" hole using a circle template on the existing pilot hole that I can use as a guide to help me "move" the pilot hole inboard.

 After a lot of time, carefully filing the pilot hole and checking with various increasing # drill bit shanks. I successfully moved the pilot hole down and I am left with a #14 hole. Using an oak block clamped in between the horns, I used a #14 drill bit by hand and turned a pilot hole in the opposite horn. Sure enough...I have now a marker for the hole that measures 0.0320". Not perfect...but a darn good recovery. 

Then I very carefully reamed both holes to 3/16" and the AN3 bolt fit is tight. 

Drilling the elevator horns - 1.5 hours

I need to drill the elevator horns for the pushrod. My horns are fairly aligned, but I would say the left side horn is the one further back. So I marked the hole according to the dimensions on the drawings.

I started drilling the hole first to #40, then up to #30. Then I made my spacer block and drilled in a drill press to get a good drill jig. Placing this in between the horns, I marked the next hole by twisting the drill with my hands.

This is when I noticed a whoops. 

Turns out the other horn is a tad lower than the other one. And surprise, surprise the tallest one is the one I chose to drill. Making the other hole with less edge distance than the other 

To be exact the measurement on the other horn will be about 0.305" as opposed to 0.375" as stated on the plans. Better call Vans.

When I called Van's Tech support Monday morning, we went through a few options of what I can do. Even adjusting the "height" of the elevators was an option if the pivot point isn't drilled. I asked about welding. Vans response is it's possible. But the disadvantage there is that the power coating needs to be removed for welding and a new coating be applied. Very important on these weldments as they can easily start to rust. Ultimately tech support felt I was going to be just fine with my particular issue. Although I didn't have 2x edge distance (0.375") I was better than 1.5x edge distance (0.28125") and it was still very safe.

 Personal note: I can take a file and walk that pilot hole down, allowing my new pilot hole to gain a few thousands in edge distance. Theoretically if I do it perfect I can move the pilot hole 1/32" (0.03125")....realistically I'll likely be able to move the hole 1/64" (0.015625"). That would allow a final edge distance of 0.320"

Installing the F-781attach plate and finished drilling the VS - 4 hours

 Started in this morning by preping and priming the F-781 attach plate. After about 3-4 hours of dry time, I decided it was good enough to rivet onto the VS. 

I started to open up the two upper #40 pilot holes in the VS rear spar. Now, here is the part that sucks. Unfortunately I cannot use a drill jig to drill these. Rather than completely disassemble and drill in the press or on the table with a drill jig. I choose to drill them by hand and ream to 3/16" in place. And the bolts are a tiny bit loose. Especially the right one. Crap

 

So talking to Vans Technical support, we determined that the best course of action is to use an NAS6603-4X bolt for this right hole. Its an 1/64" oversize and will allow me to hand ream the bolt for a perfect and snug fit. We also discussed using NAS close tolerance bolts for the left hole in lieu of the AN3 bolt as the NAS bolts are consistently just a couple thousandths larger in diameter than AN3 bolts and have a tenancy to snug up some of these areas where bolts easily slip into holes.

Moving onto the elevators, I need to start drilling the elevator horns. Fortunately I have not cut the ends of the HS stabilizer allowing for a prefect alignment of the elevators 

One item that I want to do is install nutplates in the elevator tips which will allow me the ability to install extra weight in the elevator tips if needed in future balancing. The existing tooling holes are perfect for an AN3 bolt.

Next I temporarily installed an elevator in the HS and now started to scratch my head on how best to drill the pivot hole. I need a 1/4" bushing to protect the bearing. A trip to home depot was a bust, however I stopped in at Hobby Wholesale and they have a whole selection of various brass tubes. Sure enough they have a 1/4" brass tube that will allow me to drill a pilot hole. 

Fabricating and fitting the F-712D elevator stop - 4 hours

Looking around for the angle material for the F-712D and I just cant find AA6-125X1X1 1/4. However I have the same thickness material in a larger size. AA6-125X1 1/2X2 (Something like that) which was scrap from an early part of the fuselage build.  The angle will work just great as I can cut it down. The inside radius is a bit thicker, so in order to make it work I just need to increase the dimensions very slightly. 

I did a rough cut of the angle with exaggerated dimensions.  I will trim it down after I have drilled the mounting holes.

After marking and measuring everything. It was time to start drilling #40 pilot holes. 

Next I started opening up the holes for AN3 bolts. Stepping each one up #40 to #30, to #21 (Which allows a #8 screw for perfect alignment and "clecoing") and finally reamed to 3/16"

 Now its time to set the 1/4" offset on the vertical stab. Using lines I had previously drawn when setting the horizontal stabilizer. I can easily set the offset. But I just was hit with a huge crap. When trimming the VS-702 I set the proper height according to a straight VS. However...those measurements change when you begin the offset. I had good edge distance on the  F-781Vert. Stab attach plate, but as soon as I moved the 1/4" offset....nope. 

I dug out some 0.063" material that I have and cut out a new F-781Vert. Stab attach plate. I then moved all the rivet holes up about 3/16". Bent the plate between two pieces of oak and bingo bango. Done. 

 The drilling of the attach plate to the VS-702 is fairly easy after this. The front of the VS is aligned with the 1/4" left offset. A straight edge held to the hinges at the VS rear spar to set the proper height of the front of the VS. Clamp it all down and drill with the 90deg pneumatic drill.  

After that's done, I removed everything allowing good access to use a drill jig and upsize the attach plate/HS mounting holes to 3/16"

 In case you are wondering....I use a ton of washers during preliminary assembly so I don't use/abuse the nylon locknuts. I want to reuse the nuts for final installation and I feel much better about it when I know the nylon is "new and untouched"