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Ok gents....
Today I was working on a brass chassis, only my third and first of this kind. All was going well until I tried to go back and solder a joint in very close proximity to one I had already finished. The first joint came undone and kinda messed the whole thing up. I tried for several hours and only got frustrated and had to eventually walk away with plans to get back at it tomorrow.
So, my question is....how does one protect already completed solder joints when one has to solder another joint in very close proximity to an already completed joint?
Thanks,
John

If you can, use alligator clips in between the areas. It acts as a heat sink and helps protect the other joint. NOT a foolproof solution, but it does work in many cases for me.

Guess I'll have to find some tomorrow, any suggestions? Especially since it's your chassis design I'm trying to replicate! The one you did for the Modified Coupe. I'm having trouble doing the bracket for the one screw attachment.

John, use a heatsink. A couple things that should work are the metal alligator clips like those on a controller & wooden spring clothespins. Both can be narrowed up to fit in real tight places. Department & auto parts stores will have quite an assortment of different size alligator clips, if you need to buy some. How many watts was your soldering iron?

Ah, fresh from a similar experience here on my first brass chassis............

I don't know anything about heat sinks, but I found that I needed to be sure that the original joint was supported, as it had been when I first soldered it, using, in my case, wooden toothpicks, while I was soldering the next joint close to it. If it's supported as it was, then even if the original joint melts, when the solder cools, it will re-form as it was before. :twocents-mytwocents:

Allan

I was actually using Harry's small torch method. What wattage iron should I be using to build a brass chassis?

Another thing, tin the plate/bracket first. Sand it smooth and try again. With solder already on the plate, you should just need a little heat for it to flow. It will take less time and less chance in effecting other areas.

Metal works better as a heatsink than wood. I have used a pair of heavy needle nosed pliers with rubber bands holding the handles together. Also, in brass model railroad work, they use different solders with different melting points. Do the first joint with the hotter solder, and then the heat needed for the second joint, made with the colder solder, shouldn't melt the first joint.

I'm as far from being an expert in this area as anyone can be, but the one that I used was a Hakko FX-601 with a 1/4" chisel tip. I had the temperature set two clicks down from maximum, which is 570 degrees C., so about 460 degrees C. (or 860 degrees Fahrenheit). At that temperature it was hot enough to work with 0.040" naval brass and anything less than that, as well as piano wire to 0.055" diameter.

Allan

you can use moist towel, silly puddy, clay, play dough as a heat sink

just put it on the spot you want protected

Im a torch guy to lol

John, your use of a torch explains much of your problems.:) For a solder iron, I'd recommend something in the 45-50 watt range. If you were working with a lot of 1/16" thick brass, you'd want something with more wattage. I mainly use a 50 watt Ungar I've had since the 70's. If I was in the market for a new iron, the Hakko FX-601 mentioned by Allan is one of the best stand-alone (not a soldering station) irons on the market today & is what I'd buy. It has 67 watts, a built-in heat control with 5 or 6 temperature settings, & Hakko makes 15-20 or more different tips that fit it.

If one was into using solders that melted at different temperatures, I'd use 2% silver bearing, 4% silver, & 6% silver solder. I don't know what the train builders were using, but I have 2% & 4% silver for chassis building. No, I wouldn't recommend wooden heatsinks be used with torches, but a hardwood like maple would be better than nothing at all. I do keep a pair or bamboo chop sticks handy when building, but not for heatsinks. John, get some metal alligator clips & try them with your torch. Try the auto parts department of Walmart or other department store, the electrical department of a hardware store, or an auto parts store itself. These places should have quite a choice.

Thanks for all the great advice gents. I will update on my progress tomorrow and what method(s) I use and have success/failure with.
Thanks again,
John