Plastic pushrod guides!
 

Hi guys, I need some advice.
How important are the approximately 1/4" plus or minus long plastic guides inside the plastic pushrod covers? I am building a kit that calls for them on the elevator and rudder pushrods at approximately 3 to 4" apart along the pushrods. The instructions indicate that they should be gllued with a small drop of CA glue if they are a little loose. If they are reasonably important, will someone tell me how in the dickenshttp://www.rcuniverse.com/forum/js/f...ular_smile.gif do you get them on the wire pushrod? I even tried to heat them slightly, but they still will not go over the wire. Thanks for your help!

Jim

RE: Plastic pushrod guides!
 

They wouldn't put them there if they weren't important. I've got them in several of my ARF's. They keep the pushrods from flexing in the tubes so they add stability to the plane's handling and the pushrods themselves.

RE: Plastic pushrod guides!
 

I think your describing something a little different.. do you have a pic? Are they thewire pushrods that run the full length from servo to surface and there is a plastic tube that fits over that like this
http://www3.towerhobbies.com/cgi-bin...LXPJX9&P=7

... Or.... Is it a plastic tube in a tube type deal with a short piece of 2-56 threaded wire at each end located in the inner tube?
like this:
http://www3.towerhobbies.com/cgi-bin...XFU92&P=ML


Either way you will want to support them as oldtyme says or the rods will flex under load and you will get very little if any movement out of the surface being controlled. Usually it's easier to make your own supports out of some lite ply or even thick balsa as they can customized to attach ot whatever is needed as the rod travels back through the fuse. During building you could even plan ahead and drill small holes in the formers to accept the pushrods being sure they run a straight line from servo to control horn.Mike

RE: Plastic pushrod guides!
 

Thanks for your reply. The push rods run from the servos to the elevator and rudder the entire length of the plane. (Almost) Anyway they do run through the formers and are supported at each former. The guides that I am referring to are little plastic pieces (1/4 to 1/2" long cut from a smaller plastic tube)  that go directly over the wire pushrod (attached at approximately 5" o/c along the wire with CA glue) and then are inserted inside the plastic pushrod guide.

Anyway; I am probably did it all wrong, but I figured out a way to get them on the wire and glued in place. After about 8 hours, I finally got everything reassembled and am moving on. Thanks again for your reply.

Jim

RE: Plastic pushrod guides!
 

Hmmmm i have never heard of or seen that system before... Pushrods should be a 10 minute deal for each surface.

RE: Plastic pushrod guides!
 

LOL!  I had to reajust all of the Pushrod lengths and bell cranks after taking the push rods out of the plastic guides through the servo compartment due to the bend at the servo end. The only way I could figure to get them out easily was to remove the clevis's. I already had them adjusted and had to completely redo everything after I removed the pushrods. I had already removed the elevator and rudder along with all of the hardware, to cover them. Anyway, I am about 25% along with the Monokote covering since. Hope to be finished with the Kit by end of next week. I am working about 6 to 8 hours a day on it.

Any way this is a Great Planes Kit and seems to be reasonably standard. I have already bought another Great Planes Kit and it has the same pushrod assembly.

Again, THANKS for your interest in my problems.

Jim

RE: Plastic pushrod guides!
 

I've been building kits,scratch, arfs etc. for more than60 yrs. but have never heard of what you are explaning? Maybe I don't understand?

RE: Plastic pushrod guides!
 

They come in some of the Top Flite kits and others as well. The outer tube is supported in the structure and then you have the metal pushrod that goes in the tube. What he is describing is that the kit also includes a length of something we'll call a tight fitting support tube that is in the shape of a "star wheel". You cut this support tube into 1/4 to 1/2 lengths and push them onto the metal rod. If they are not tight fitting..........which all of mine have been....... you add a drop of thin CA to bond them to the metal rod. Then when the metal rod is inserted into the plastic tube is has support and it also keeps it centered in the plastic tube and prevents bowing within. This is not new and if you look in one of the Top Flight Manuals.....like the C182.........you'll see what the OP is talking about.

RE: Plastic pushrod guides!
 

Thanks oldtyme. I understand exactly what you explained but have not seen this used. Just shows we can learn something at any age ha.

RE: Plastic pushrod guides!
 

Below is a link to the plane's manual that I am building. The pushrod sleeves that I am trying to describe or noted in item 6 on page 34. Maybe it is explained better that my attempt.

Anyway, I figured a way to get the little plastic sleeves made and over the wire pushrods. Probably not what they had in mind, but I am pretty sure it will work the way they intended.

http://manuals.hobbico.com/gpm/gpma0160-manual-v3.pdf

Jim<br type="_moz"/>

RE: Plastic pushrod guides!
 

Jim,

Those are nylon skids just to reduce the points of contact and friction between the oversized sleeve and the wire.
I imagine that sliding them along the wire must be hard, as the manual states there is a tight fit between both.

Just verify that your solution allows completely free sliding movement of the wire within the sleeve or plastic guide, and that the skids cannot slide by themself after a while to the end of the sleeve to interfere with the free movement and full deflection of the elevator and rudder.

Nice model.

Best luck!

RE: Plastic pushrod guides!
 

Yes, Lnewqban is correct. They are intended to help the rod slide in the tube. They are a pain in the *****. I had them on a couple of planes I bought from another modeler, and when those planes needed rebuilds I did away with those slides. There are much better systems available. If you can keep your rods and tubes fairly staight you don't need the little slid guides.

RE: Plastic pushrod guides!
 

The pushrods in this plane are almost straight without any bends. Leaving them out was my first inclination, but I finally got them in so I guess they will stay until I total the plane or have to rebuild the fuselage.

Jim

RE: Plastic pushrod guides!
 

Not to pick fly crap out of pepper on this subject...............they are not intended to "help the rod slide in the tube", they are intended to help keep the wire rod "centered" in the tube. If they were not installed the metal rods would have a lot of room to flex in the tube and make the control "flakey". If the plastic tubes were smaller then the "guides" would not be needed but the fact remains that the tubes are large for the size of the pushrods so the "guides" are needed to keep the rods centered.

RE: Plastic pushrod guides!
 

Isn't a smaller diameter tube the best way to keep the rod centered in the tube?

Yes, but then, the friction would be higher, especially after some time, after which rust and dirt accumulates.

In my opinion, not the best system in the world anyway.

RE: Plastic pushrod guides!
 

I totally agree with you but the larger tubes are what are supplied with some of the kits. When rigging most of my kits with my own inventory I use the Du-Bro plastic tubes with steel rods and have never had a problem even with models that are 20+ years old.

Cheers

RE: Plastic pushrod guides!
 

This push rod system is the weight of a servo.  So on my Supersportster 60 kit I cut my servos into the tail. And it worked great !

RE: Plastic pushrod guides!
 

That's good for those that don't want an almost scale look. A real plane doesn't have controls hanging out of the fuselage and that's what this plane is...........a scale plane........so it only wants the minimal control stuff showing.