Hi guy's,does this look safe or should take it apart and do a z-bend?I'm using here a golden clevis with a safety clip from Golden-rod,I'm also using the same clevises on the control surface,just wondering what you guy's think?
Thanks

where are the 2-56 lock nuts, unless the other end is z-bend.

you use z-bend when you dont have these clevises.

the whole locking nut thing is new to me,the pushrod can't turn because of a bend where it exits out the fusalage,well let's just say it shouldn't and I can't turn it by hand but it does move back and forth just a hair.I'm doing it the way the instructions say to install it but I did replace the cheap plastic one's with the golden clevis,I'm also following the post about locknuts with goldenrods because I use them also and never read anything about locknuts.Sorry for sounding dumb on this one.

If there is a clevis at the control horn vibration can turn the pushrod having a clevis at each end. I would find a lock nut to be safe. Why take the chance. Just my opinion.

Ya,I could put a lock nut on both ends but would it be even safer to install a longer rod and use z-bends on all of the servo ends?I know z-bends are very safe so mabe I just answerd my own question,is it worth the time?I think so I just hope I don't butch up the wooden part of the pushrod when I take off the shorter threaded rod.

I would just put a nut on the outside end, but thats me

Your setup looks fine as long as the clevis is not wiggling around on the threaded rod. If you can feel movement, put a nut on it. There is no way that those rods are going to unscrew. Even if they could turn, the would unscrew out of one end and into the other. As long as you have the length of threaded rod in the clevis that you have, the threads will bottom on one end or the other before it can part company with the clevis. It just ain't going to happen.

However what is the deal with the throttle linkage, why the big bend in the cable and where is the lock screw on the quick link. I'm guessing from the photo that your quick link is set way to tight on the servo arm and isn't rotating on the arm correctly. That bend in the cable stands a chance of folding over from the looks of it. Make sure the quick link turn freely, but isn't so loose it might pop off. I use them for throttle linkages and I've at times put the Jam nut on way to tight, giving me the condition your photo show. If you take a picket knife and work it under the jam nut carefully, all the way around it, you can get it loose enough to turn easily on the arm.

Don

I really like using a clevis instead of a z-bend.
The tolerance is so sloppy on the metal clevis that it will vibrate and wear the threads out.
So even if the clevis cannot turn you use the lock nut to keep the clevis from vibrating on the threads and wearing them out.

Personally I like a Z bend on the servo, and the clevis on the control horn, but clevises on both ends should work fine.

Like Campgems said the cable looks like the quicklink looks like it is binding, either the keeper is too tight or the hole in the servo horn needs to be drilled out.

Another thing I like to do with cables is to tin the end with solder so it has no chance to unravel.

Yes it was binding,the hole was to small.Does this look like a better set up on the throttle?when I get the engine on and the front clevis hooked up to the arm on the carb I can solder the servo clevis in place,and about the rudder and elevator pushrods,could I just solder the servo clevises on instead of a z-bend or lock nut?(that would take out the little play it does have)sounds like the easy way out to me,I just want it to be right.

Your set up is fine with the exception of the throttle cable you got issues there as already mentioned. I prefer to avoid 'S' bends to exit a fuselage all together and they promote control blowback pushrod flexing but do prevent the pushrods from becoming a turn buckle. I normally use "Z' bends at the servo and a clevis at the control horn.

Those kind of clevis locks are a royal pain and you loose then in an instant. I much prefer the tried and true piece of fuel line. They are easier to install and last longer if you keep some Large size fuel line around for the purpose.


Those rolled metal clevis are OK but one with far less failure modes is the hayes plastic (black) with a metal pin, Lock nuts are not ever needed and the seam cannot spread allowing slippage on the threads under load. but don,t use this type of metal pinned plastic clevis on a throttle pushrod at the engine, Use only all plastic there if the throttle arm is metal.

John

you must solder the throttle cable into the clevis, but before you do it make sure that the nyrod is not restricting the movement, its a Bit_h to shorten it when the clevis is soldered.
soldering the servo clevis [:-],
well for me its not the preferred connection because i like to have this degree of freedom otherwise thats it and you cannot change anymore.
Lock tight doesnt do it? get 2-56 nuts you will need them in the future.
meanwhile i would go with some nylon clevis instead of soldering them permanently.

Alex

L bend with a quick link.

One of the first things I was instructed not to do was use bends in the push rods. This induces sponginess and slop in the system and may lead to flutter. I go to quite a bit of trouble to make a straight run of the push rod from the servo arm to the control horn at the control surface.

The above is only my opinion and has worked good for me for almost 40 years of R/C modelling. However, I see many airplanes now with bends in the pushrods and they seem to be o.k. with this! Still, it doesn't change my mind on having bends in the push rods!

In the instance shown by Cowboyfk, I would use a Z-bend, Snapper Keeper, lock nut; or, a solder clevis, so as to keep the rod from being able to spin. Cowboyfk, a simple fix for you, would be to install lock nuts.

Another option would be to just add a little solder to the end or the servo clevis/threaded rod. That would do the same as adding a nut if you can't locate one. It's ok to use dual clevis setup but only one should have the capability of turning.

Z bends are great, they will never fail you and will prove realiable...

I am partial to the Z-bend myself.

While Z bends are fairly reliable they are a poor choice if you need precision as they soon wallow out the hole in the servo arm and become sloppy. For sport and general use, okay, for precision Z-bends are a NO-GO. A properly installed clevis or ball joint is far superior.

Rodney, what do you mean the Z-bend will wallow out the hole? If you mean they will wear the hole bigger, why would they do this anymore then a clevis or other type of connector? If you mean that Z-bends shouldn't be used on large scale or pattern or on other high load applications, then maybe I would agree. However, I won't agree that Z-bends arn't every bit as "Precsion" as any other type of connection, sorry!

It is very difficult to get a perfect 90 deg bend in a short radius. The resulting Z-bend does USUALLY tend to enlarge the hole slightly. I don't see it causing a noticeable problem though any more than the silly notion of expanding/contracting Gold-N-Rods and the like. People just need to get over their belief that the average sport plane will be bothered by these things or that their "skills" will allow this to be detected noticeably.

Especially when used right, meaning you have the Z bend on one end (servo) and a clevis on the other end (elevator, for instance) so you can do mechanical adjustments.

I've been using the L bend with quick-links that hold the L bend in place. I've had no problems at all with them at all.

CGdid you get to fly anything when you went out to see your mom?

No. It rained pretty hard all day on Friday, then it was pretty windy on Saturday, and I left at about 10 AM on Sunday, so no joy at all this weekend. And, of course, now that the company has decided that we need to do the tests at Louisville, we're going to have to work this weekend.. yeah, Easter weekend.. nights too.. yuk.. have to work when the airport load is down.. so I won't be doing any flying this weekend either.

CGr.

You are gonna forget how pretty soon.

I prefer a z-bend on the servo arm.

I've had clevices and quick links, and sometimes the sides of the links can actually bind against the servo arm when the servo is at the extreme end of its travel.

As for wallowing out the servo arm hole.. I have to agree with others, a clevise, a quick link, will also do so. A ball joint won't.

As for precision... I don't know. From servo arm to control surface.. there are many different places where precision can be lost by a little slop here and there. And let's not forget about the simple possibility of flexing. Not only the flexing of the mechanical parts/pieces, but of the airframe itself.