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Alternatives to the Flimsy FT Push Rods

Ryan O.

Well-known member
#1
Now, first off, the reason that I posted this in the balsa section was because getting into balsa has revealed a ton of new linkage options for RC. One of my favorites is the Sullivan Gold n' Rod and Gold n' Cable, which are both really percise and adaptable. They work better with standard servos however, but they can still be used on 9 grams with some work. The other alternative's I've sewn are the push rods slightly thicker than what are used in FT planes which are then put through a tube to reduce flexing, but this has to stay in a relatively straight line compared to gold n' cable which works great for going around a corner. If you want to be a little cheaper and use less complexity, there ia always the thickened up wire, but eventually the wire will be too large for the servo arm. If you are willing to modify your design you can sometimes use a pull pull method which uses two thinner wires or even cables attatched to the opposite sides of the servo arm, and attatched to a two sided control horn, but these can be finneky and complicated. Lastly, you can always zip tie on a barbeque skewer as well. Do you have any tricks and substitutes for the pushrods typically used?
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Monte.C

Well-known member
#7
These cable systems keep coming up on my radar. Think I'm going to have to try one of these after lock down. Is there any drawbacks or quirks you have found to them?
It must have been maybe 1978, I was a kid and building a sailplane kit. All balsa, and I even followed through with skinning the whole thing with that film they use, to stick and shrink it with an iron. But I was 12 yrs old and never got it in the air.
But yeah, those Gold-N-Rods were the thing at that time, at least for sailplanes. They work beautifully but I don't know how tight a radius you can get out of them. I might guess you could push it to a 7" radius maybe? But those micro ones @speedbirdted posted look great.
 
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Monte.C

Well-known member
#8
Right now I've got these "Snakes" in a drawer here, didn't wind up using them yet. But they're smaller, much lighter, and they're plastic inside of a plastic tube. They weigh almost nothing.
I just fiddled with one - they work fine but I would want to lubricate them with a plastic-safe silicon grease. Might get down to a 5" radius.
 

speedbirdted

Well-known member
#9
These cable systems keep coming up on my radar. Think I'm going to have to try one of these after lock down. Is there any drawbacks or quirks you have found to them?
While I did on the Cub I found that I didn't need to actually use the entire cable housing when I built a Willy Nillies Eaglet using them. I would cut small pieces that would fit into the fuselage formers to prevent the wire from wearing into the fuselage. I also did it to cut down on tail weight and make the linkage have less friction. This was fine from a mechanical standpoint since the distance between supports was only a few inches at max and didn't let the cables flex at all. It's probably a good idea to take a similar approach with foam; every time I've run an unsupported music wire pushrod through a piece of foam it eventually ends up deforming the hole it runs through and affecting the pushrod actuation.

Hell if you have some linkage stoppers you don't even need the pushrod kit; just pick up some thin aluminum or brass tubes if you can't find anything plastic, and run it through wherever the music wire will be in contact with foam (and perhaps a little more for extra support) You can get away with using Z bends if you don't have any linkage stopper just fine, though it doesn't let you easily adjust the pushrod length or remove the pushrod from the tube (things having just one linkage stopper on one end lets you do)
 
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Turbojoe

Well-known member
#11
Right now I've got these "Snakes" in a drawer here, didn't wind up using them yet. But they're smaller, much lighter, and they're plastic inside of a plastic tube. They weigh almost nothing.
I just fiddled with one - they work fine but I would want to lubricate them with a plastic-safe silicon grease. Might get down to a 5" radius.
I found a stash of and prefer the Dubro micro pushrods but they got WAY expensive if I ever need to buy more so I'm always looking for alternatives. I went to Hobby King and lo and behold those snakes you linked to actually show to be in stock! Absolutely nothing else I might have been interested in was though. I'd love to give the snakes a look see at that price but the Hobby King shipping would be three times the price of the parts. I would have loved to pick up some more things to make the shipping cost worth while but their inventory almost looks like they're clearing everything out to close up shop.

Joe
 

TooJung2Die

Well-known member
#12
One of my favorites is light wire inside guide tubing. You can use much lighter wire when it is supported along the whole length. I use a z-bend at both ends. A piece of heat-shrink tubing allows fine tuning of the wire length. A couple drops of CA on the heat-shrink locks the wire length.
 

Turbojoe

Well-known member
#13
One of my favorites is light wire inside guide tubing. You can use much lighter wire when it is supported along the whole length. I use a z-bend at both ends. A piece of heat-shrink tubing allows fine tuning of the wire length. A couple drops of CA on the heat-shrink locks the wire length.
I've got plenty of music wire. The hard part is finding that blasted tubing in a size and stiffness that is useful for a reasonable price. HK shows exactly what I want at a great price but none in stock. :cry:

Joe
 

TooJung2Die

Well-known member
#14
The hard part is finding that blasted tubing in a size and stiffness that is useful for a reasonable price.
I know. I've been looking for more of those $1 shower caps with the tubing inside. They're nowhere to be found. :mad: That was the best source of guide tubing I ever found. Have you tried looking for 1/8" OD gauge line tubing. Used for automotive vacuum and oil pressure gauges. I have a few feet left over from a boost gauge install. Same stuff.
 

Turbojoe

Well-known member
#15
Problem with that tubing is it's always coiled and damned near impossible to get it to lay straight again.

I dearly love and fully support Dubro but we all know they outsource the tubing used in their pushrod kits. Where the heck do they get it? Almost $9.00 for their #852 .032 micro pushrod kit borders on ridiculous. I have plenty of piano wire AND the connectors. All I need to find is the straight tubing for a less than horrendous price. I just found an old stash of R/C supplies and I have 6 Dubro #852 micro pushrod kits so I'm in no rush. I'd just like to find that tubing and be ready to rock if need be. I may start looking into smaller carbon fiber tube instead as in some cases it's cheaper than the plastic from any company even remotely related to R/C. It seems R/C to many companies means quadruple normal price. :mad:

Joe