Soldering end caps & sheet brass

[Col. Batguano]

After hours of shaping, my nose cap is ready for an end cap now. But, try as I might last night, I couldn't get the solder to stick to the brass. I tied the silver/tin mix, and the tin/lead mix that comes in soft "roll" form at Home Depot, and for flux the standard goobery stuff that comes in a tin. The same way as I join pipes in plumbing, or solder wires together (though I use a soldering gun for that). All it did was burn off and catch fire. The solder just balled up and did not bond to the brass. I was using a Mapp gas torch for heat.

Then, as I kept it up, the flat plate I was trying to solder the shaped plate distorted and then a big fat hole got burned through it. Big mistake. I cut another flat piece of brass, and then tried the ox-acetylene torch, and a fluxed brass brazing rod. That didn't work either. It just burned through the base plate (.032" brass) even faster.

Thank goodness it wasn't the shaped piece that took about 5 hours to shape and trim to size.

Am I doing something wrong, or using the wrong solder and flux? Where can I get the right stuff if it's wrong? I have a base to solder on to a domed patch box later on, so I REALLY don't want to wreck that.

 

[ZUG]

Your using too much heat and burning the flux and an Oxy-acetlene is WAY too hot for solder and even brazing on thin sheet brass. Once you burn the flux you just better forget on having the parts joined. Here is a funnel I silver brazed together with a hardware store propane torch. I use this for most of my brass and steel sheet metal joinery. The last picture is of the flux on the joint it is flux used for silver brazing. Apply heat until the flux starts to turn liquid - touch the silver brazing rod to the joint apply a LITTLE more heat until it flows - remove the heat - let cool. The same process is used for lead solder just use the correct flux and DON'T OVERHEAT IT :wink:

 

[okawbow]

Sounds like way too much heat. Try a small flame propane torch, and don't heat the solder directly.

If you can "tin" the edges that are being soldered first, it will go together easier. Be sure all surfaces are chemically clean before starting. Don't touch areas to be soldered.

A good fit of the parts helps also.

 

[Col. Batguano]

Am I using the wrong kind of solder and flux then? It's the same stuff I use for sweating copper plumbing pipes together. If it's the wrong stuff, can I get the right stuff at the big box hardware stores? I hate to have to wait for mail order if I don't have to.

 

[eggwelder]

I`ve used all kinds of solder, even straight lead. clean clean clean. not too much heat as mentioned. I use a plumber flux found only in plumbing supply warehouses(FAR too powerful for the general public :grin: Plumbers only!!! ). comes in a dark blue bottle with a red label.have never seen it anywhere except the suppliers.

I`m not a plumber

 

[Scota4570]

Lead-tin solder and acid paste flux is fine. Tin the joints first. Use a small ball of steel wool with flux and a little solder dripped on it. Heat the meal to be later joined sufficiently to melt the solder as you rub it with your steel wool ball. It will be all pretty and silver. Let it cool. Jig it up. Gently warm it and when it get glossy silver again add a little fill solder. You could probably do this with a heat gun, but, use a propane tourch and tread lightly.

Trying to solder sheet metal without tinning it first is not likely to work. Same with ribs, pipes and such. Tin it first.

 

[Vaino]

When the "body's" inside shape conforms closely to the 1/8" thick brass end piece, all surfaces that will be soldered are gone over w/ 220 grit paper and assembled and secured w/ baling wire.

From the inside, borax flux is applied and 1/16 dia. hi temp silver solder is laid along the entire seam.

A Mapp Gas torch supplies the heat and when 1200 degrees is attained, the silver solder flows....making a nice, strong joint.

The high temp solder used probably isn't necessary, but it's so easy to do.....Fred

 

[Col. Batguano]

is the borax flux you mentioned generally available at most big box retailers, or is it a specialty store thing?

I see Brownells sells a silver solder chip paste concoction, which I think is flux and solder all mixed together, and intended to be gap filling as well. It's spendy too. Like $65 plus shipping. I don't think I need that stuff do I?

 

[Vaino]

For all my low temp soldering needs I use Swif 95 solder paste which I bought from Brownells and which they no longer have. The solder paste eliminates the need to tin parts.

For some of my soldering, the high temp stuff is used as in my post.

The flux is very old and it's white and I'm guessing it's borax flux. .....Fred

 

[rich pierce]

One of the reasons I prefer one piece nosecaps.

 

[Col. Batguano]

These are great tips. Thanks. What I know is that this is sort of an elemental skill, and such a very small part of gun building, it doesn't get discussed much here (compared to the browning process, or finishes like AF for instance). If it were tough, I'd have read about it more.

Unfortunately, my past soldering experience was limited to sweating a few pipes together here and there, or tinning some wires together. Not what I need to do here.

What else I know is that if you use the right techniques, materials, and equipment, it should be super easy. If one of the prior 3 are missing, nothing you can do will EVER make it work right.

 

[Vaino]

A couple of parts that require high temp solder are shown below along w/ a Pbox that has the hinge plate low temp soldered on.

The RR pipe is formed around a mandrel in a vise, but the inside dia has a groove which is filled in w/ high temp solder. This enables a shorter tab.....why have a long slot?....Fred

 

[Col. Batguano]

Success! The problem was that I was using either the wrong type of flux, or the wrong type of solder. Though it was low temp stuff, I went and got some acid core silver solder last night, and some (what I think was) acid based flux. It became super easy once I used that. For good measure, I also got the other types of solder and flux they sell. It seems that acid core solder is for pipes, and rosin core is for wiring, I was always told acid is bad. the answer is; not always.

 

[Zonie]

Wiring is about the only thing rosin core solder will work on. It's totally worthless for anything else.

For soldering brass or steel a hydrochloric acid or zinc chloride works fine.

Both of these fluxes will eventually attack the base metal so they need to be washed off after the soldering is complete.

 

[shunka]

re acid vs rosin - As Zonie said above.
if you ever need to do "hitemp" silver solder, the "borax flux" isthe common big box of Borax found in the grocery storev-va 4 pound box is around $4 :

http://target.scene7.com/is/image/Target/13315486_Alt01?wid=450&hei=450&fmt=pjpeg

This is sprinkled on the clean part and the part heated until the borax melts and flows. It is used in blacksmithing the same way - to keep air/oxygen away from the joint. Remember to keep the flame moving, heat the part not the solder, nd don't overheat the part.

yhs
shunka

 

[Gustavo Hoefs]

Zinc Chloride...... 50/50 solder..... Stained glass supply

 

[Zonie]

It should be mentioned before one of our members tries it, Borax will not work for normal soldering.

The high temperature silver solders (and others) mentioned is speaking of temperatures over 1100°F.

As a reference point 1200°F is about the temperature that aluminum melts.