install those jam nuts!
 

Hello, I still consider myself a newbie. I am starting my 3rd year in this VERY addictive hobby.
Over the winter I did some re-working of my metal, Golden Clevis by Sullivan. By re-working ... I mean adding jam nuts on the rod/clevis. I never considered this to be necessary since the rod could not turn with the other end being soldered or a Z bend. BUT..... what I didn't realize is the fact that there IS slop at that clevis without the jam nut. AND that is only part of the problem. That slop will wear at the threads and you may eventually have a clevis failure. NOT a good thing!!:rolleyes: I am sure this is not big news to seasoned flyers, but I just posted it here for guys like me that let this go on without realizing a problem.......lownslo....

Bob

install those jam nuts!
 

Bob - That's great info!

I've had problems with the jam nuts coming lose as well and then the whole thing vibrates in a disconcerting manner. I use non-hardening loctite on all metal clevises now as well as using jam nuts.

install those jam nuts!
 

Hi CaffeenMan, Which color is the non hardening
Loktite? Is is the light blue??...lownslo

Bob

PS. I guess I could go read the labels.... Im looking for the easy way out! :D

install those jam nuts!
 

Mine is in a red bottle and the loctite is blue. But I don't know what colors the other formulas are. It says non-hardening on the label. If it says "Permanent" or anything of that nature, don't buy it.

install those jam nuts!
 

I now agree 100% with adding jam nuts to clevises, after almost losing my Spinsation tonight. Halfway through a flight, the rudder started wagging uncontrollably. Fortunately, I was able to land without incident. Come to find out, the Sullivan gold-n-clevis had stripped from the threaded rod.

I've built over forty planes, and this is the first time it's happened to me. The rudder on this plane is a very aggressive application (approx. 60 degrees throw each way), and high loads splayed the clevis apart where the two halves meet, causing the threads to lose contact. I used a jam nut previously, but removed it after it vibrated loose all the time. I've now run a piece of fuel tubing over the jam nut, and halfway up the clevis, thereby keeping the nut from loosening. This stiffens the connection considerably, and keeps it from working against itself.

At first, I thought the Sullivan clevis was to blame. However, I think any clevis would have done the same, given the conditions. Luckily, it was the rudder, instead of one of the elevons.


Robb H.