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Servo
connection up front. Picture #2(Right) (2) 0.070” solid CF rods attached with Kevlar thread and thin CA glue to a Central Hobbies 5/32” hollow CF tube. The 0.070” rods are still 48” long and the 5/32” pushrod tube is about 3 inches long. Leave the 5/32” hollow CF tube long for now. Get the servo 100% mounted and ready for action. It really will not matter whether it is mounted on its side or not. I choose a side-mounted setup as shown in a later picture. But the fact is it really is of no consequence. Trial fit the pushrods in the sleeves. You may need to clean out the paint that is in the Teflon sleeve. This will usually just pop right out when you slide the pushrods in. If not. Use a small rat-tail file to open the exit up until its friction free again. Leave the elevator horn connection alone for now. The pushrods are long and need to have one connection setup perfectly before you go to the other end. Make sure that you have about 1” of travel each way out of the servo while pushing the “Y” pushrod. Its important there is no binding of the “Y” as the separate rods enter their respective Teflon sleeves. Its OK to have a little extra of the dual pushrods extending out past the balsa sticks and Teflon sleeves but don’t make it a really long run. These rods can flex a little so keep everything as close as possible but still allowing for friction free movement. Cut the length of the 5/32” Central Hobby pushrod off until everything is the proper length. Remember you have a ball link and a Titanium end to glue into the now single side of the “Y” connection. The way I do this is to test fit everything together. I actually thread my ball link onto the Titanium fitting and slide the fitting into the Hollow CF tube. Everything is attached to the servo arm and the Elevator servo powered up and centered. I then move the servo its maximum amount of expected travel and look for binding. I make sure I have just a little extra travel room in case needs change in the future and I need more elevator throw than expected. Once all the parts are dry fit and assembled make sure everything is the proper length. If all is correct epoxy the Titanium end into the 5/32” piece of Hollow CF pushrod. I use 30 min Epoxy and make sure I have a good lather of it inside the Hollow pushrod. Wipe any excess of with paper towel. While the glue is all still wet I hook everything back up to the servo just as if it was ready to fly on this end of the pushrod. These connections will hold everything in place while it cures. Elevator Control Horn
connections On the Elevator side of these pushrods you now have the 0.070” solid CF rods sticking out about 10-12” past where they need to be. You are going to cut them and attach a threaded link. The pushrod kits come with a brass solder link just like Dubro sells. I don’t like the brass ones but have used them. If you choose the brass links cut the threads off to make the threaded part about ½ of its normal length. This will make the link stronger and not bend so easy. Bob Violet Models produces some solder links similar to the Dubro ones except they are stainless rather than brass. I choose these. I don’t have a part number but give them a call and ask for the stainless steel solder links for 2-56 sized rods. The BVM links are not designed to take a 0.070” rod and the holes are a little undersized This is only a couple thousands short of the right diameter. I just hold the link with pliers and drill out the holes to a 0.073” or a #49 drill bit. Don’t choose 0.070” because that’s your pushrod diameter. You need some room in there for the epoxy…3 thousands slop seems to work for me. This gives me 1.5 thousands all around the rod. More works too. Now use the same technique
as up front. Install the solder links whether they are the stainless or
the brass versions onto the clevis. Install the clevis on the elevator
control horn. Once this is all connected just as it will be in flight.
Turn your Elevator servo back on and make sure it’s centered. Use
masking tape to hold the elevator halves centered, mark the location to
cut the 0.070” solid CF rods. Use a Dremel cut off wheel and cut
the rods slightly longer. Now test fit everything together trimming the
CF rods back until they fit perfectly inside the solder link but have
no gaps inside the connection. The brass fittings have about a ½”
to 5/8” of socket to accept the CF pushrod. The Bob Violet fittings
are not as deep they are about 3/8” socket depth. Clean the CF pushrod
with alcohol and take some 100 grit sand paper and just scruff it up a
little...not too much as you will cut the Fibers and make the pushrod
weak. Just scuff it lightly. Now use 30 min epoxy to glue the pushrod
inside the solder link. Make sure you have a really good lather of epoxy
inside the hole and good coverage. Once all in and covered good with glue,
wipe any excess epoxy off the connection from the outside. Leave a small
bead of glue at the joint. It should look a little like a Plumbers sweat
joint. Let everything cure!…..and its all done and Important:
To change the brass fittings, remove the clevis from the fitting. Take a Bic lighter and hold it under the brass fitting to heat it up. Once hot, the epoxy will be liquid, take a pair of pliers and just slide it off. The epoxy will soften with the heat and the fitting will slide right off. Clean the old epoxy off while still soft using 100 grit sand paper and then follow the steps above the re-install a new fitting. The finished product looks like Picture #3(right) showing the elevator servo connection. The picture below shows a JR 8417 digital servo side mounted. The Servo arm is the Hangar 9 Aluminum Servo arm part #HAN3431. This is the part number for the JR servos. The Ball link is a Hangar 9 4-40 threaded ball link with a 2mm screw going through the servo arm. The Titanium fitting going into the CF pushrod is the 4-40 fitting for the 5/32” Central Hobbies Pushrod.
Servo
choices…. Now I use this system exclusively right now on F3A models for Elevator control. Someday I might find something better. It is not the easiest thing to build and install. But so far it’s the lightest and stiffest connection I have seen. You have to grab the elevator halves and try to flex them opposite of each other to really appreciate the benefits of the this pushrod setup. As for Radio interference issues because of the CF rods, I have had none. I Fly JR PCM “S” receivers in my F3A models and run the Antenna inside a tube inside the fuse. I have also flown JR PPM “FM” Receivers with no troubles. You mileage may vary but I see no issues using the CF rods in the fuse. Well I think this sums it up really well. It’s long but covers the bases. The opinions above are my own and do not reflect on any business or company providing materials. Some modelers with disagree with my methods or choices. These are my models and I make the choices. I tried to give some of my reasons why I make the choices I do. The advice given previously is worth exactly what you paid for it. Just that: Opinion and Advice! Any Questions? Give me an Email. - Troy Newman
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connection
for clarification purposes. The 4-40 fitting gets glue in place later
on….
connected.
And
Picture #4(right) is the Elevator Horn connection side. This
picture shows the MK medium Aluminum control horn, and the MK 2mm ball
Bearing clevis. The silver link is the BVM stainless solder link drilled
out slightly to 0.073” (#49 drill). And the connection is 30min
Zpoxy resin. 
