Question About Soldering

[JPar]

I'm fabricating the fuel filler & foot valve assembly for my model Fairbanks-Morse engine. It's comprised of three pieces of 1/8" brass pipe. Two of the pieces are cut with a saddle joint, to be soft-soldered to the third piece. My soldering skills are OK, but not great. I would like this to look nice when the job is finished. So, my question is, is there something that can be applied to the pipes to prevent solder from sticking in areas where I don't want it to? I've been told that graphite (like a pencil) will work, but the pipe is shiny and slippery and I'm not sure the graphite will adhere well enough to do the job.
Thanks!

 

[Ed ke6bnl]

I like silver solder for that type of project

 

[benmychree]

Yes, I agree, silver solder; I think that with vibration, soft solder would fail.

 

[Ed ke6bnl]

If you have tig silicon bronze would be another choice. I suggest getting some silver solder and some silver solder flux and practice and you will find it valuable for many dissimilar metals that need to be brazed together.

 

[markba633csi]

Using regular tin/lead solder would work ok, the devil is in the execution. Both joints would need to be done simultaneously. I would fasten the main piece in a vise, then use baling wire to hold the other two pieces on so they won't slip. Flux the joints with liquid or paste flux, then heat with a propane torch and touch the solder to the part- as soon as it begins to flow, stop heating. It will only take a tiny bit of solder, surprisingly little. You'll see it run around by capillary action almost at once.
Mark

 

[Karl_T]

Use silver solder paste. Put in on carefully, wipe away where not wanted. Then you go no huge blobs of silver solder to mar up the appearance.

https://www.ehow.com/how_7677143_use-silver-solder-paste-flux.html

 

[P. Waller]

GTAW works well on copper and the weld will essentially be the same color as the base metal, send it to a welding shop if you do not have the equipment. If done well it will look like this.
http://kgmarinefabrication.com/wp-content/uploads/2017/10/pipe-welding-copper-tig.png.png

 

[eeler1]

Theres a chalk-like material, (soldering talc) that’s supposed to prevent the solder from attaching to the work. Comes in sticks that you then wipe over the work where you don’t want the solder to stick. Of course, careful application of flux and solder could achieve the same result.

Not addressing the issue of whether a stronger material is required for your application.

 

[Mitch Alsup]

Zinc chloride is a liquid flux that attacks the heated metal oxides to enable solder to stick and clow into the joint(s).
Generally comes with Stay Brite silver solder

 

[f350ca]

Haven't tried it but have heard White Out for a type writer works, if its still available.

Greg