PLEASE HELP! Brass, super-glue, heat? Ahhhhhhh!

hi , go to a radio spare part store and ask to see a heat sink , they come in several sizes , you solder the first parts together then leave to cool apply the heat sink as close to the first joint as possible and then solder the next one and so on . the heat sink stops the heat from traveling up the brass , good luck , i used to make my own from scrap brass rod and screws , but mine were for full sized jobs in power industry . cheers ian

The above tip will help a lot.
Solder comes in diffrerent lead/tin ratios as well, the differance for you is different melting points. Start with the highest and work your way down. sorry I can't tell you the melting point for different mixes.

Captain,
The previous two posts have great ideas - I would use them both but I would add one thing - I'd make some sort of jig to hold the assembly in place while all your fabrication was going on - this will help in a couple of ways - it will act (partially) as the heat sink that Ian recommends, plus it will help hold stuff still while you use the soldering iron. If the jig is strong and holds the parts tightly enough, this may hold the parts together even if the solder from one part melts when you add another part.
Also, alligator clips can be used to clamp some bits together and keep them together while you solder.
I'd consider getting one of those clamp/base arrangements that electronics stores sell - it's a heavy-ish base (or a base that's screwed to the desktop) and has several moveable arms that have alligator clips on the ends.
Good luck
LeeTree

The clamp / base arrangement Lee is talking about is commonly known as "Helping Hands." Aside from soldering, no modeler should be without them. Most even come with a magnifying glass built into them that is also adjustable, and believe me, you may not even need the heat sinks with them. You can pick one up for about $20 at just about any craft store.

Just remember the golden rule of solder: "In quick, out quick." Set the iron to the temp just above where the solder melts, then solder the joint quickly, before the heat spreads too much. Also, if you keep the iron on the solder too long, it becomes brittle.

demono69

You could also try a resistance soldering iron, which is an insulated plier handle with tweezer tips. You grip the part you are soldering with the tweezers and press a pedal to apply electric current. It heats up fast but the heat is localized so other things don't fall off. I know that you can find them at www.micromark.com but they can be a bit pricey. Maybe RadioShack?

I can definitly recomend "helping hands" i have 2 in differing sizes also dont try soldering big areas in one go. Like MIG welding just do a bit at a time then that way the job wont heat up as much and melt the other joints or distort the parts. also you could try an apoxy type glue which may be easier than soldering...Gregers

A couple of things to add to this thread...

One is that there is a heat sink paste available that you can mold around parts to prevent them from coming apart while soldering nearby. I get mine at Orchard Supply, but welding supply houses would certainly carry it. It can be great when soldering large assemblies.

Perhaps the best suggestion is to add, whenever possible, a mechanical aspect to your brass assemblies - drill holes, pin, slot, or whatever wherever possible. This way, your structure is stable before soldering, which always is a good state of affairs! Even .020 wire can be cupped a bit on end with a grinding wheel to give a bit more purchase on another wire.

HTH

Kurt

Along with these other great ideas, you might try putting your piece in the freezer for an hour or two before soldering. If the previous solders are properly done and cured, the welds will not be adversely affected by the temperature, and it will allow you to get the part you're working on up to temp while slowing the transfer of heat to the other parts.
Glenn

Ditto to all the other tips, i.e. heatsinks, fixtures etc. As a 50 year model railroader I have soldered lots of brass on some very intricate parts. Wet rags on adjoining parts is another form of heat sink. Also you might try "TIX" solder which I'm sure is available at Micromark. Most solder has a melting point of around 400-450 degrees. TIX has a melting point around 250 as I recall but is just as strong. I also have a resistance solding unit which does localize the heat, but the work needs to be fixtured generally for best results. Do check out Micromark. Most tips mentioned in the previous answers are available there.

There is a wealth of info here. May it should be retitled "Soldering 101" and made sticky.

On the subject of soldering, one of the best things you can do is to control the amount of solder that flows into the joint - this is one case where less is usually best. For small parts, I use a razor blade and slice off very small sections of solder - perhaps .010 thick. This disc can be further chopped if needed; for example, I find that half a disc is more than sufficent to join two .020 wires together.

Always use some kind of flux too - I prefer liquid to paste, and apply it with those new microbrushes you see in hobby shops these days. Be sure to wash the part off before painting.

Kurt