[nomads]

Help on this subject, please.

I am experinced with regular soldering using a Soldering Iron and lead/tin solder.

I've just run into a problem while trying to solder some clevises onto pushrods that came with an Alpha Trainer. The pushrods have a shiny appearance (as if they were chromed, although I doubt that). Simply put, regular solder does not want to adhere strongly to the pushrods.

I've tried a range of temperatures with a temp controlled iron, and I've tried 50/50, 60/40, and also Deans "Racing Solder" with 2% silver. I've also tried acid and resin fluxes.

I think (but I don't know) that the answer might be to use a brazing technique with a pencil flame torch and some "silver solder" that I assume would have to contain far more than 2% silver. I've "googled" this and am still confused since it appears that brazing may require up to 40% silver in a non lead base "solder".

If you know about this subject, any suggestions would be most appreciated.

Thanks,

Bill

[moo]

Quite possibly they are electroless nickel plated, you usually have to niclel plate under chrome anyways. You could file off the plating where you want the solder to stick.

I'm surprised a trainer does not come with threaded push rods, they should be confident of the length required in a kit.

[tech1]

Silver soilder will be much stronger for your application.


Moo is right, you need to take off the outer coating and get to bare metal.

Good luck

[nomads]

Originally Posted by moo

Quite possibly they are electroless nickel plated, you usually have to niclel plate under chrome anyways. You could file off the plating where you want the solder to stick.

I'm surprised a trainer does not come with threaded push rods, they should be confident of the length required in a kit.

One end is threaded. The other end uses the so called "L Bend keeper" with a nylon clevis. This clevis has a slot cut in it which clips over the rod after running the short "L" through the control horn on the servos. I don't think these are very good so I cut off the excess rod and tried to solder on a metal clevis.

I will try filing off the plating and re-soldering (later today or tomorrow).

I'm still curious about the brazing technique, however, as from what I read a brazed joint is far stronger than a soldered one (not that more strength is needed for this application -- it would be just one more potentially useful tool/technique to know about).

Thanks. Bill

[Sonic Boomer]

Hey Bill, with regards to silver soldering, your should be able to find the solder wire and appropriate paste flux at your local welding supplies store. The wire is much stiffer than other 'soldering' products and requires significantly higher temps. The parent metal will need to be heated to a dull/medium red, the solder will also turn dull red before it melts. On small or light gauge materials, a pencil flame butane torch MIGHT be enough, but I would suggest MAPP gas - you can usually get it at the same place you get torch propane. The MAPP gas is an acetylene mix and will work well. Coat the parts to be soldered and the soldering wire with flux and start heating. The flux will dry and form into little glowing balls before it flows over the parts and into the joint. That's all there is to it. But.. if you don't have the stuff on hand, it would be cheaper and less bother to just set aside (or pitch) the links and get some normal ones from your LHS.
Boomer

[cf-drg]

It's so easy here are some pics... Like Bommer said you can get the flux and solder at a welding supplie store, the MPS gas you can get a Canadian Tire,Home Depot, or any hardware store.. I hope the pis are in order ... Here we go.. Flux the objects (Flux pic), then melt the flux like it is melted glass (Meltflux pic), get the flux and object to a dull red colour and add some silversolder, it should only take about 1-2mm of the solder to do a clevis and rod ... The solder should just flow into the joints (solder will move to the heat), and thenlet it cool and your done (Done pic)... Hope this helps too....

[cf-drg]

Here are the last 2 pics, for adding solder and Done....

[nomads]

All right!

I found a local welding shop where I got the necessary materials.

Both the flux and "silver brazing alloy" are manufactured in Rexdale (part of Toronto). The Flux package states "For low temperature brazing", and the silver brazing alloy is a 1.6mm wire containing 45% silver.

I'll be trying it out tonight but I won't bother posting pictures of the results since cf-drg has already done that.

Thanks to everybody who responed, especially sonic-boomer and cf-drg, who explained the brazing process in simple and illustrated terms.

This is the best part about RC Canada -- all the experiance and advice that's available from fellow modellers. Thanks RC Canada!

[Guest]

That looks like it is a higher temp than you really need to do the job. Most jobs are done well with the Stay-bright silver solder kit. Much lower temp comes with its own flux all in a small easy to use quantity.

No open flame required just a good high temp soldering iron like the one from Canadian Tire. If you use an open flame and you are not experienced it is easy to over heat the small components and change the structure of the wire. (usually it ends up annealed or softer and has a tendency to bend easier).

If you do use an open flame bring the soldering area up to temp by flicking the flame over the area. When its the right temp the solder will flow into the joint without the flame. If you have to heat it until it starts to change color the silver solder has to high a melt temp.

Let us know how it worked out for you.

Dennis

[moo]

I don't think an L bend or Z bend would fail on a 40 size trainer.
Z bend tools are available at any hobby shop, and at 20 seconds a bit quicker than a solder-on clevis.

Perspective, gentlemen.