Is there a way to add the thread to the non-threaded side of a pushrod? Would like to refit my plane with ball-links instead of 90 degree bends at the servo end. I know I could glue in, but if I can screw in...would be better.

No, it's just about impossible to do that. The threads on pushrods are rolled into the metal instead of being cut. If you try to cut the threads using a die (if you could do it at all) you will find that they would not fit in the clevis you were trying to use. If you want to attach a clevis to the pushrod simply get a solder clevis and solder it to the pushrod.

Ken

NM,
I use solder on clevis at the servo.

Most prethreaded push rods have rolled threads, the actual unthreaded portion is too small to thread, if you run a nut onto the threads, you will see that it will actually go past the threads then slide down the metal. As RC Ken said, buy a solder clevis or just a solder on threaded brass thread sold for that purpose. I used to have some mild steel rod that I customed threaded but the brass threads work just fine and much less work.

Randy

Hmmmm...ok. The Ball-link is plastic...so would it be a good idea to solder a brass threaded coupler to the pushrod then screw into ball-link...or would it be a good/bad idea to just epoxy the rod into the ball-link's shaft?

Do not use epoxy at all on any metal pushrod parts. Epoxy gets it's strength from it working into the pores of the material it is bonding. If you put it on a pushrod there are no pore in the metal for it to bond to. I can assure you that it would fail in flight. Definitely not a good idea.

Ken

RO347.

This is a good time to learn about..... pull-pull........ control lines. Nothing needed except fishing line. No slop. easy to adj. Lightest system and costs nothing.

Can't do pull-pull on throttle and I believe (from a different thread) that this is what he has plans for.
If doing throttle use the treaded ends at the carb end and then use one of these at the servo
http://www3.towerhobbies.com/cgi-bin...4&I=LXE114&P=K
No soldering at all and solid connections with adjustments available.

Ha...the throttle problem was solved...This is a redo of 2 elevator and 2 aileron linkages. Setup for a pattern plane.

And don't use electrical solder. Scuff up the rod with sandpaper, wipe it with acetone or alcohol and use silver solder and a good 100W or even 200W+ gun (not a pencil iron).

I usually agree with you Charlie, but I have been using electrical solder on pushrods for over 40 years without a failure.

The electrical solder works well for me also. Just be sure and shine the metal rod with sand paper before the solder job.

If I just need a clevis on one end and an adjustable length on the other. I will solder a brass clevis directly to the rod on one end and a solder on threaded end on the other end.

Since this is a setup for a pattern plane, have you considered using graphite pushrods instead of the steel? They're lighter, stiffer, and you just glue threaded ends into the CF tube. They're a little more expensive, but for the weight savings and additional stiffness, they're often worth the money.

Brad

Ken, when I make carbon fiber pushrods for my planes (I do on all of them) I usually take Sullivan 4-40 rods with threads on both ends, cut about an inch and a half past where it turns smooth, score the metal with a dremel and then epoxy that into the carbon tubes. Then I use Dubro 4-40 Safety Locks.

http://www3.towerhobbies.com/cgi-bin...?&I=LXWH35&P=7

These homemade connections go on all control surfaces except for rudder and throttle. Are you saying this is a bad idea? Not being flip, honestly curious.

I agree with Sonic and Miniflyer, electrical solder will work well for this application.

Epoxy used on carbon fiber is fine as the epoxy will grip the carbon fiber. But epoxy on metal is a no-no and a recipe for disaster.

Ken

But I'm epoxying metal rods into carbon fiber tubes. I score the metal with a dremel first, but still.

That's what makes the horserace. Can't argue with what works, but when I'm doing it I use the best I've got on hand. I always keep some Sta-Brite on hand. Got some 3% silver solder at a local dollar store had and I hope they get more! I'm a real belt and suspenders kind of guy (and usually build overly heavy because of it). I'll put 30 hours in a 10 hour ARF assembly. ;-) And, knock balsa, I've never had a catastrophic in-flight failure of a mechanical or electrical connection (including hinges). Had a throttle arm pull off a SK engine but that was a design flaw - four pressed dimples to hold a the throttle arm in place. Just made for a longer than expected flight.

You should be fine Pete as long as you score deep enough to give grip or "tooth" to the metal without weakening it. Kind of a "ribbed" effect like you see on Robart hinge points but not as deep and not the full circumference.

Pretty much what I do. That makes me feel better.

I have FILED small "V"s on it also. Remove any oils on the shaft somehow. All these methods will work just fine. I use Rosen cored solder also. Works fine.

When I'm gluing 2-56 rolled thread rods into whatever I'll run the un-threaded end through a 2-56 die..
It won't cut threads deep enough for mechanical connections but an inch or two of shallow threads is enough to give the glue a good grip.

I don't see why it wouldn't work on rolled 4-40 rods too.

This is what I do too.

I don't know about this application but Green Loctite made to hold bearings & shafts in place works great in the industrial world. Unless you heat this stuff it ain't going anywhere. I bet you would tear it up trying to take it apart. I'd trust my plane to it.

I'd scuff the rod with a bit of fine sandpaper to shine it up, clean it with carb cleaner, alcohol or some such and put a little in the female part and a bit on the rod, push it together, wipe any excess, and give it a few minutes. You cannot take it apart. I've used it under torque. No way it will move.

I will do it on my next project and report on it.

What I was wondering about is him useing a ball link on the control surface end? Unless a metal or heavy duty control horn is used putting a ball link on that end is a bad idea. Even then it is not the best idea. A clevis can push and pull in line with the horn. A ball link will try and twist the horn with every deflection. On a standard plastic control horn the deflection is a lot. It is doomed to fail and cost you the plane. The ball link should be on the servo end with a heavy duty arm. Then a metal clevis on the horn end.

Just my.02 David