jdeluyck

My Feedback: (6)

For those that have used the carbon fiber pushrods from Central Hobbies, I have a couple of questions:
[list=1][*]What adhesive did you use on the ends?[*]Have you tested the strength of the bond between the end and the rod?[*]If you have used long rods, how often did you place supports for the rod?[/list=1]

I am considering using this type of pushrod on my Ziroli Hellcat, but I am concerned about the strength of the ends. Any feedback is appreciated.

Steve_JR

My Feedback: (6)

Use JB weld. It is a cold weld and the pushrod will break before the end will break. -Steve

jdeluyck

My Feedback: (6)

Steve,

What about the strength of the bond of the JB Weld and the CF rod? I know that Central Hobbies recommends that, but .......

Jerry

Steve_JR

My Feedback: (6)

...trust me on this. Most if not all serious competitors for flying use C/F rods with titanium ends. They use JB weld. The JB weld will make the end permanantly bond to the pushrod. Those aerobatic planes are going under a lot, I mean a lot of stress as compared to a scale warbird. You don't even really need C/F rods for a Hellcat. If you properly clean the end of the rod and put the right amount of JB weld on, you will have the strongest pushrod on the face of the earth. -Steve

OnTheEdge

How does one determine what size CF rod to use? Central Hobbies sells several different diameter rods/titanium ends. I'll be using two rods about 7-8" long for the rudder on a 33% Edge.

jdeluyck, For some added piece of mind, some guys CA glue a small piece of aluminum tube at the ends of the CF rod to keep it from splitting/fraying. Probably over kill but I intend to use it.

bpryor

My Feedback: (45)

Hi OnTheEdge,

I've already communicated my experience with Central Hobbies CF rods and titanium ends to jdeluyck (he's a hard guy to convince, but I guess if you have as much time and money as he probably does in his Hellcat, I would be too. )

I second everything Steve has said. I've used this setup on 27, 35 and 40% planes. I've used Central's 3/16" rod and 4/40 ends on all of them, but I have only used them on ailerons and elevators so I don't think I've used anything longer than 6". For a 7-8" run I'd probably use their 3/16" with 6-32 ends. I've used CH's recommended procedure for gluing the ends to the rods using JB Weld. I first lightly roughen the inside of the CF rods by rolling up a piece of 220 sandpaper and spinning it around inside, then I roll up kleenex soaked in rubbing alcohol and spin it around inside the rods until no black residue is present on the kleenex, then mix up the JB Weld and you're done.

I've never had one come apart, and I doubt they ever will. I've never had an end fray either. I cut them with a fiber cutting wheel on the dremel to get a clean cut without any fraying, and the titanium ends have a flange on the end about the same diameter as the rod, so I don't think it will ever fray.

jdeluyck

My Feedback: (6)

Thanks for the feedback all. Bill you are correct I do have a large investment in this airplane. I intend to use the CF rod on the elevator, that is the one control surface you absolutely cannot have a failure with..... Thus my skepticism.

TampaRCGuy

My Feedback: (282)

I get my cf rods from Daryl Caddy, I think Central gets them from Daryl as well. I am using one as the pushrod to the tail rotor on my heli and it works great! I will be using them as the pushrods for the ailerons on my 40% Extra as well.

Daryl suggests using a black flex ca for the ends. He said there has never been a failure. I beleive him as ca bonds incredibly well with cf and the flex stuff is as strong as epoxy without the weight.

Kregg

My Feedback: (45)

Ok Guys, I was going to us CF push rods in a scale project of mine and several people told me not too because of radio interference problems. I was looking at a longer CF rod, about 20" long, running down the fuse and my antenna was in a tube mounted to the floor of the fuse running the same direction. It has about a 4" seperation from the proposed CF push rods.

edge_fanatic

My Feedback: (4)

Hmmmmm....'tis true that carbon fiber rods are conductors....But I've run my antenna down the inside of the fuse of my H9 Edge 540, within an inch or two of the CF rods, and my radio checks good out beyond 100 feet each week.

I put the antenna inside a stiff tube having a slightly larger inside diameter than the antenna wire, and run the tube inside the fuse...

NSSHERLOCK

Re: Carbon fiber rods. I have been making control rods for some time using CF and epoxying an all thread 4:40 rod inside. I use small 4,40 self locking nylon nut at each end. This makes a swell strong rod that cannot pull out and is a lot cheaper than the titanium rods. I have see several of the left/right threaded titanium rods snap right off, but I'll grant you it was from crash damage and who knows the stresses thereof.

Jemo

My Feedback: (5)

Carbon fiber rod's or tubes can be used anywhere metal can be used.

Take a look at a Helicopter with carbon fiber side frames, carbon fiber tail boom, and carbon fiber tail pitch control rod. Helicopters use the same radio gear as fixed wing, just use your head and do a good clean installation, no rubbing, etc, etc.

tkg

My Feedback: (1)

The weak link is not the cf/titanium/JB weld connection, but its the control horn or the hinges.
The JB weld joint will take many hundreds pounds in pull and the control surface will fail first.

sideshow

My Feedback: (11)

I have actually had a JB weld joint come apart on my Central Hobbies CF push rods. I know everybody is gonna say "you didn't clean the joint well enough". It was cleaned very well and it still happened. I can't explain why. On the rod that came apart I just used a dremel to clear some of the cured JB weld from the grooves of the Ti end and reapplied the JB weld. So far, so good on the repair.

On my current project, Aeroworks 29% Edge, I am using Darrol Cady CF rods with 4-40 threaded rod and rubberized CA. The threaded rods thread themselves into the CF rods so the joint is mechanical as well as chemical. The rubberized CA is easier to use as well. Both work great and I won't use metal again.

Bob

NSSHERLOCK

RE: Carbon Fiber I also assemble golf clubs with CF shafts. Some cautions regarding CF. With golf clubs, you wrap the cf with tape where you intend to cut it to keep from fraying the Carbon fibers. Also, with the model pushrods, I would not advise tapping them for threads for assembly or for roughing up a gluing surface. Once you cut through the fiber thread, the strength is gone and may not be replaced by JB or epoxy or whatever. As a side note, I have also made push rods of aluminum tubing with 4.40 all thread epoxied inside and they are pretty strong also, especially in the push pull mode with no bending moments involved. You need to adjust travel so the rods are not bending at the extremes of servo travel due to interference with linkage.

jelaird

My Feedback: (1)

Just did the JB Weld thing on the short elevator rods for my DPM Extra. Lookout....take a viscous substance like JB and install one titanium end...all is well. Stick the other end in and the first end pops out. Looks like a little air compression going on. Blocked it up in a bar clamp, it's ok. Little worried about the couple of slips in & out and the bond left over. Next rod gets a tiny hole drilled with a pin vise in the middle for ventilation/pressure equalization. Has this happened to anyone who had the JB Weld fail?
Jack

NSSHERLOCK

RE: CF Rods glued with JB Weld. I have always put a clamp on the rods untill they set up to prevent the creeps that may occur. If they are too long for a clamp, I just set them on end till set. I haven't had the trouble with pressurizing them you mentioned. I would not drill a hole however because I think it might create a stress point where the rod could eventually break. I have no data to back this up, just my TLAR engineering. I usually pump the titanium piece in and out a few times to be sure the glue is well spread, then wipe off the outside to remove the overage.