I just got my Dolphin today. Has wood push rods. I also have the rods left over from the Nexstar, and am wondering if I should change them out. Is there any benefit of wood push rods?

Thanks.

Wood push rods are fine. They might be slightly heavier than some alternatives (line carbon fiber). I'd use the wood ones if they look good (straight, stiff, etc.)

Wood push rods are very reliable and when they are installed properly they do not bend easily. I would go with the stock ones in this Dolphin.

Years ago I was wondering about these wooden pushrods, then somebody told me with the z-bends its the most reliable connection.

Thanks guys. Never seen them before.

Watch closely to make sure neither end can snag on a former. My first ARF required me to deep six the wood rods and put in plastic in plastic rods.

They are a tried and true method, even though they date back to early days of servos. Even in the days of escapements, they were used, but not as push rods but a torque rods.

Personally, I won't have them in my plane.

Don

In the old days (years that ended with BC), wood was the prefered material. Hard balsa and dowels were both used with the metal ends over lapping the wood by an inch and wrapped in thread and glue. Later improvements added heat shrink tubing or even wraps of monocote to replace the thread and glue.

The main advantage to wood was temperature stability when comparied to Nyrod. Your trims didn't change as the day warmed up.

Oh as to the date BC, that's (Before Carbon).

Check them to make sure they are straight and use them. Obviously you'll want to check them for interference and stuff just like any other push rod. One thing I like to do is clean the wire portion really good with alcohol, scuff it with sandpaper and use a little epoxy where it inserts into the wood. Then put the supplied heat shrink over this. I just feel that it makes the joint a little stronger.

As others have said, wooden pushrods are great. They have been around forever for a reason, they work. There is one mod that I prefer to make over the supplied heat shrink to hold the rods in the wood. Use thread first, CA, then the heat shrink. Look at my review of the World Models Super Chipmunk to see how I did this
[link]http://www.rcuniverse.com/magazine/article_display.cfm?article_id=814[/link] Scroll down to the "Elevator and Rudder Pushrods" section.

Basically what you do is this. Install the metal rod in the wood. Then use cotton thread to completely wrap the dowel rod where the pushrod goes in to it. Apply thin CA to the cotton thread to harden it. Then put the heat shrink of it. This will last forever and give you a good reliable connection between the pushrod and the dowel rod.

Ken

Benefit? Not that I know of. OTOH they work however I have not used one since 1972.

If you use one, be certain the wire connectors are supported between the wood/carbon and the horns, plus another support at ever 18" minimum. Just some wood strips every 18" or so will suffice. Like the # sign and can be just as leaning. What you want is to stop any sway in any direction caused by G-Loads. In addition, stopping any fluctuations (flutter) created by vibrations and/or g-loads.
These fluctuations are like control flutter which they can well initiate, and can play havoc on a servo's insides. An ounce of prevention is worth a pound of cure.

The best long distance pushrod is a wire 1/16 to 3/32 in a well supported plastic / glass tube.

Back in the early '70s I knew a young fellow well on his way to the top of Pattern that was losing more than his share of models, mostly due to servo failure. I looked over one with dowel pushrods, explained my thesis, he revamped his wooden pushrods with the supports, and 2 years later he had not lost an airplane. He flew in the early Tournament of Champions but we lost touch so I don't know where he went to as I soon returned to the Republic.

The potential oscillation deal from the wood pushrods' unsupported bulk has made me leery of them. They look like they could start buzzing and wipe out a gear train in the right circumstances.
Like Hoss says, well supported [guided] wire that goes from point A to Z has to be the safest method.

Light weight, weather stable, resistance to side deformation (wire rods "wobble" and distort against pressure - for better or worse), no danger of interfering with antenna or metal-to-metal radio interference.

Taper the ends to prevent catching on bulkheads and wrap the short wire ends with thread and then soak that with CA. I like and use them.

I left the carbon fiber and went back to wood about 10 years ago. They work just as good and are cheaper. And I think they have a more similar coefficient of linear expansion so the trim doesn't change as much from summer to winter.

So these rods are already attached and heat-shrunk to the metal rods. The wood ends are tapered and wrapped with what looks like electrical tape. The wood part is 16" long.

Again I'd like to ask why I shouldn't replace them with the metal rods from the Nexstar. Sorry if this was mentioned, somehow I'm just a little confused. They do seem to be a HAIR lighter, but nothing to write home (or to you guys) about. They are FAR from being straight (wood is straight, but metal part goes in at an angle at both ends, not part of design). And I don't see how to support them (no given hardware).

For the metal rods from the Nexstar, they are in good shape, plenty long enough, and the tubes are long enough to extend from the exit hole in the fuse all the way to the servos if I wanted them to.

Thanks for the advice...

I would be leery of wood ARF pushrods, you're taking quite a leap of faith in someone elses' work. Control linkage failures is a sorry way to lose a plane.

The metal push rods in your Nexstar require a plastic guide tube that needs to be supported at both ends at minimum. Supporting it in between is helpful too. This will likely require some modification to the fuselage, adding balsa braces, etc. (all very doable of course) If you are ready to take on that sort of modification, fine. It is your plane after all. I figure that there is no reason to fix what isn't broken. There is no need to do the additional work. The wooden push rods will get the job done fine. If anything, I'd just make new wooden dowel push rods if the ones supplied with the plane were questionable. I subscribe to the keep it simple philosophy.

My World Models Rambler 45 uses a wooden dowel for the elevator. It has two wires that "Y" at the end to control each half separately. I was leery of this at first but I decided to run it. The plane is extremely fast and very aerobatic. There has never been an issue with fluttering, binding, flex or anything else. It works great. My Phoenix Sukhoi used dowels for both elevator and rudder. It was a VERY aerobatic plane and there was never an issue other than me dumb thumbing it into the ground. Your Dolphin isn't as advanced as either of those planes. It will be fine.

Kat, each of us has their own preferences. Truth is that all will work, or you wouldn't see them used. If you are more comfortable with the rods from the Nexstar, use them. The only two issues would be, are they the right length and will they do the job. Actully three questions, will the ends fit correctly.

I like making up my own rods. I know what I have that way and I'm sure that they fit well. I am not a fan of a Z bend because to get the rod through a hole in the servo arm or horn, the hole has to be bigger than the rod or else you couldn't get the bend in the rod through the hole. This translates to a sloppy fit. Clevises in fresh arms and horns will give a tight linkage. That's me. Others will give different advise. You need to decide what will work best for you.

Send us some photos of your progress.

Don

OK, thanks so much guys.

You can make a Zbend wire go through a servo arm with a slop free fit. Take a length of that same wire and sharpen one end. Heat it with a cigarette lighter and push it through your favorite servo arm hole.
Work the Z bend through the hole it don't forget to place a drop of oil on the tight fitting joint.
You can also use $20 calipers and a $10 Harbor Freight numbered drill index to correctly size and make perfect sized holes anywhere else on your model.