I have tried to solder 4-40 rod to GP Threaded Couplers using 60W iron and GP sliver soldering kit but i have failed.
I worked according to rcuniverse article clean,flux,heating up the coupler to a point the solder would melt right into the joint but this has never happened. The solder could reach this melting point even thought i let the coupler to be heated for more then 10m.
After many tries i got a help from a electrical technician which used it's own solder and flux to directly melt the solder (not heating the coupler) this method seems to work .

what i really would like to know is :
1) what i was doing wrong with GP soldering kit ?
2) is the electrical soldering going to hold ?

thanks

Silver solder has a much higher melting temp than regular solder. Normally you will need much more than a soldering iron to melt the solder. If I'm using silver solder then I use a mini torch! This seems to be your problem. Find a little more heat!

I've successfully silver-soldered using a 140-watt soldering pistol. In fairness, the wire was only a little over 1/16" in diameter (.078).

What is the diameter of your silver solder wire? Mine is only about 1/16" diameter. I had a friend who gave me some silver solder once, about 1/8" in diameter. I couldn't use it cuz I couldn't get something that large up to temperature. Is your flux clean?

I believe you when you say that you cleaned and fluxed the parts properly. But I've had problems like that in the past, too.

Is it possible that after you cleaned the parts you may have wiped them down with a contaminated rag or paper towel? Something that might have had some oil (or whatever) on it?? Or perhaps you touched it with your hand or whatever (body oil)?

If you were using a 'lightweight' soldering iron, it's possible that the wire absorbed the heat away from the joint. in other words, you couldn't apply the heat fast enough.

Here's a little tip. Melt a little blob of solder onto the tip of your soldering iron. Then apply that blob to the joint. That little blob is NOT going to be part of your solder joint. It's only function is to transfer the heat.

When you can feed the solder from the opposite side of the iron and the metal is hot enough to meit the solder on its own, you'll have a great joint.

As far as using electricians solder with rosin flux, it's not as strong as silver solder.

I had a nightmare of a night trying to do the same thing. Here's what helped:

Sand the rod ends to get any finish or oil off of them.
Clean the rod ends with alcohol.
Coat the rod end with flux and insert it into the coupling.
Use silver solder but dip about 2-3 inches of it in the flux and coat the solder with it.
Heat up the joint with a little torch.
After it's hot, touch the solder to the joint, the flux starts to sizzle and the solder sucks into the joint.

They were very strong when I was done. Make sure to grab the rod and coupling and try to yank it off. Mine would not come off.

When I put the flux on before the solder, it just boiled off and did nothing to make the solder flow. When I dipped it in flux and applied both at the same time it worked great. I think a silver solder with a flux or acid core would work much better. I hope it goes smoother next time for me. It was 1:30 a.m. when I finally figured it out. Had piles of melted solder on my basement floor. What a night.

Joe

THROW AWAY THE GREAT PLANES "SILVER SOLDER"AND settle for nothing less than (Stay Bright brand silver solder )

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Thanks Guys

one more thing to be sure.
is the soldering made with the technician electrical solder and flux going to hold ?

All the points brought up here are all correct. I use GP solder with "0" problems but Im using a Weller D550 iron. Its 325 watts. The process when done properly takes seconds to complete. If your applying heat waiting for solder to flow something is wrong. This is not a difficult thing to do but the heating process must be short and intense along with the cleansing previously mentioned. If you want to properly do this get a iron with with some wattage. Small torches will work but, too much heat will foul things up also..Electrical solder should not be used for control linkages. It doesnt have the tensile strength that silver solder has. Good luck, Walt

The single biggest problem I find with people not doing a successful soldering job is failure to transfer the heat to the joint. The second biggest problem is that everything must be shiny and grease free! Thirdly - Tin everything before you solder it. What I'm talking about is to solder separately each wire and then wipe it clear of solder. Some will remain on the wire. This allows you to have the strongest joint since solder will adhere to solder.

If you use an iron the tip must be clean and have some solder melted on it. This is called tinning. The liquid solder on the tip of the iron should be shiny if it is grey and coarse appearing wipe the tip and apply more solder. Always solder with a freshly tinned tip.

Next I find it a lot easier to use a large iron to solder wire landing gear etc. This is because the iron is designed not to overheat the part or crystallize the solder. If the part is overheated or you haven't used flux the solder will just ball up and roll off the joint.

This is a link for an American Beauty 100 watt iron that will last your lifetime and mine. $110.00. Let it heat up 10 minutes before you use it. http://www.hmcelectronics.com/cgi-bi...1524/0400-0026

Also Sta-Brite and GP Silver solder is NOT "real" silver solder but a compound designed for low temperatures of around 700 degrees. I use a plumbers solder with a silver content. REAL silver solder uses a oxy acetylene torch to get hot enough to melt and costs 20 to 35 dollars a foot. See below.

SILVER SOLDERS
25% Silver: A silver/copper /zinc alloy containing 25% silver for copper, brass or steel brazing. Solidifies at 1265 F, Liquefies at 1430 F. The slightly higher melting temperatures allow this alloy to be used with 45% Silver Solder (WSX-45xx) for step brazing. This alloy is a decent color match to some brass alloys. Use with Flux WFW. 1/16!QUOT! dia. by 1' lg. WSX-2521

I hope this helps. Once you get the hang of soldering it is easy.