At our last  session we had a control failure witch brought up a debate on CLEVISES . we had the group that were firm with the CLEVISE was for "bad word" RC planes,and u/c fliers put more stress with the constant pressure,I personally had a failure on my Tudor with a control rod rotating out of the bellcrank,i did not use a jam nut to back it up. my fault!  others swear by them and say bending music wire is risky. NOW i have JULY's prize on the bench and feel like what to do  Geoffrey waiting for a vote . out

GOEFFREY,
The clevis offers a very small area of contact to take the wear and loads. Usually about 1/16 diameter. Once a clevis pin or hole wears out it becomes sloppy and the diameter of the pin is reduced due to wear, putting your plane at risk. I have used ball links for seven years on one plane with no noticeable wear. I don't think you will find any experts using the clevis, 1/16 diameter is just to small to risk after all the work you put in that plane. Control line uses more travel more often and faster movement than most RC. I have seen them break and also seen them pull out of the clevis where they are staked in. You know my vote. Hey the plane is way cool. Nice to see what a winner looks like.

  I have used clevices since the early 70s on combat ships and never had a failure.  While combat planes lives are relatively short, I put the controls from crashed planes on the next new one so the control mechanism gets quite old and used.  I believe that the loads on the combat control surfaces are somewhat greater than those on a stunter.  BUT  now that I  am flying stunt, I use mostly Ball links and pinned hinges.  although I do have a couple of planes with clevices  (stunters).
  I would ADVISE you to go with Ball links as stated above if you have the room. That is just because there HAVE been so many failures.

  Bigiron

Sometimes there is just not enough room for a ball link and its attaching hardware.  Where a clevis is necessary, I've had good luck with the black plastic ones from DuBro.  They are a reinforced nylon (like the bail joints) with a removable metal pin held in place with a metal clip.  When threaded onto the pushrod, they are tight like a nylon lock nut so they will not pull off the threads nor will they "chatter" on the threads and cause a thread failure.  It seems to me that they fix most of the issues with the usual metal clevises - the pin can't come out, they don't pull off the pushrod threads, and they don't cause thread problems with vibration.  Has anyone had a failure on one of these?
Steve

This is a controversial issue but here is my take..

I use clevises for the elevator on most everything that isn't a full blown 60 size stunt ship. The large Dubro plastic is a good one as is the Sullivan Gold in 4-40. The TwistMaster has 3 of the Sullivans with jam nuts and has been flying for 7 years without a problem. Ths is a profile with external controls so easy to see if I ever have a wear issue.

Use a jam nut plus the little clip that comes with the Sullivan and you won't have any trouble.. Do not use anything that comes with an ARF, any 2-56 clevis or anything other than the two mentioned above.

I had completely forgotten about the excellent UHP clevis.  Thanks for reminding me.

Jim

Been using clevis's for a long time - successfully.  I think it helps a LOT when you use really long control horns (1" throw or more) because it takes a lot of load off the pushrod and the clevis.  It also makes the bushings last a lot longer.  I also would never use one on the elevator to flap pushrod where the elevator is slaved off the flap.

I also apply this philosophy when using ball links, or solid wire rods - light loads = long control system life.