Scratch Built Push Rods
 

I need to make some custom length push rods and want to use carbon fiber tubes for stiffness. Does anybody have suggestions about attaching the fittings to carbon tubes.

RE: Scratch Built Push Rods
 

I've used these 4-40 Dubro couplers, nicked up with a dremel cut off wheel for the glue to grab to:

http://www3.towerhobbies.com/cgi-bin...?&I=LXD924&P=7

One on each end of a CF rod. Rod ID needs to be close to the same diameter as the coupler. Then glued in with Flash Black type of CA:

http://www.horizonhobby.com/Products...source=froogle

This type of CA doesn't harden quickly inside the rods, so I usually leave them for a few hours or overnight to harden. Accelerator doesn't seem to get far down into the rod and it's mostly airtight in there.

The black CF rods can split lengthwise so you need to sleeve the rod ends to keep them from spliting under side loads. I usually use heat shrink, but others have used brass or aluminum tubing.

I'm about to install a rudder pushrod in a scratch build jet using this method. I also used these on two Cermark MB-339's on rudder & elevator.

RE: Scratch Built Push Rods
 

Have a look here; www.petetindal.co.uk. Ray

RE: Scratch Built Push Rods
 

I just made some for a big F-18. They had to be 22" long. I used a 20" piece of Stainless Steel allthread. Slide coated the allthread with epoxy, slipped a carbon tube over that, coated that with epoxy and slid another carbon tube over that. I don't have the exact sizes of the tubes but The inner on the first tube was exact fit for 4-40 rod( .110) the second slid over the first with absolutly no play at all. The overall diameter of the final tube is about 5/16. When the epoxy dried you couldn't bend these things. The ball links just threaded on to the ends. I used some of the Skymaster 4-40 metal bearing ball links. I made the same for the rudders too. which only needed the first carbon tube. How long do you need to make yours?

RE: Scratch Built Push Rods
 

Billy, looks great, what to make me some JC!!

RE: Scratch Built Push Rods
 

Why not just buy the kits from Cental hobiies, These worlk great, the ends are titanium, and you JB weld the ends into the carbon tubes, There is a variety of sizes/diameters available.http://www.centralhobbies.com/contro...e/pushrod2.htm

RE: Scratch Built Push Rods
 

Thank you all, I appreciate the good ideas. I didn’t want to wait for an order from out of town. I have the carbon tubing and I was concerned about splitting. I need 4 ea about 11 inches long and I have the turned fittings for the ends.

I will see if I can find the Flash Black glue this morning locally.

RE: Scratch Built Push Rods
 

Before they closed Art's Hobby sold CF tubes and Titanium ends in various sizes like jetcentral.

I used Loctite Hysol to glue them together. never a failure

RE: Scratch Built Push Rods
 

Sid, I make my own CF pushrods in a similar manner to the other guys. The only variation is that I use JB Weld. It's reasonably thick and stays in place while it cures. Sometimes it's a pain to set up one end of the rod and then go to the other and pack the JB and the rod in place without compressing the air inside the CF rod which tends to push the JB back out. A little fiddling works the air out.

RE: Scratch Built Push Rods
 

Central hobbies titanium ends with JB weld. Brass tubing to reinforce the ends of the CF tubes to help prevent splitting. Never had a problem!