Soldering Brass

[rwells]

I am going to be making a small brass fuel tank for my stirling engine and will be soldering the end caps on. Plans call for using brass tubing 1.375 OD and 1.312 ID. The end pieces are 1.313 diameter, .062 thick. Question is I am trying to avoid a mess and keep the nice brass finish. Any tips on how to do the job or at least a way to clean up afterwords and restore the finish? The tank does have some fittings on the top for filling that will be soldered also. Will heat permanently discolor the brass? Does the solder penetrate the brass or just coat the outside. Any thoughts? Thanks

Rick

 

[rickharris]

Soft solder will fuse with the brass forming an alloy. Clean the brass well, heat and apply a small amount of solder - If you get the heat right the solder will flow over the brass so don't over do it. Keep the pipe end pointing down to prevent the solder running up the pipe.

Solder dislikes carbon so some people blacken the pipe with a candle flame to preven the solder spreading - Any solder that gets onto the black carbon is easily removed.

You might like to get hold of some plumbers flux - it will help keep the joint surface clean and improve the joint. In the UK the most common version is called Fluxite.


This process is called tinning. Once both parts are tinned with a thin layer of solder you can put them together and reheat so the solder melts again on both parts - Let it cool and the joint will be made.

Keeping the solder where you want it and nowhere else is the trick to neat joints. If you find you put too much on you can wipe the excess off whilst it is hot - bear in mind it is HOT about 180 to 200 Deg C.

 

[rake60]

My soldering skills rank right up with my welding abilities.
I don't have a lot of experience in either area, but I can
make things stick together.

Stink On Ice would describe my best efforts most accurately. :-[

For either process I have make a terrible mess of it then clean it up
after it's finished.

This is a mini burner I made for one of my flame licker engines.

Before and After....

Rick

 

[Mcgyver]

Rick2 you're modest, that looks great. i have to make something for my fire eater (none of my kids would let me steal their doorknobs), might follow that look.

Rick1, don't sweat it (pun)...worst that can happen is you take it apart, clean it and retry. Any excess solder and heat marks can be sanded/polished off. work carefully, using only as much solder as you need. and use soft solder, silver solder takes too much for thin walled brass fabrications....if you're new to this keep in mind that you can through way more heat into than is necessary with propane...that won't help the solder and might warp stuff(although a tube is a stable shape - more a problem with a box shape). get clean, put on some flux, assemble and warm it slowly until the solder flows

the wet paper towel trick. 1) despite all precautions you got a glob of solder that will be a pita to remove. while everything is hot, put the torch on the glob for a second or two and wipe it away with the wet paper towel. minimal solder will be left, easily sanded off. 2) you've an end done, or may both and you're trying to solder the pipes - lay some wet paper towels or rags over the soldered parts to act as a heat sink.

i made brass tank years ago and did a mini photo tut on it - just for giggles here's a link
http://bbs.homeshopmachinist.net/showthread.php?t=13891

 

[rake60]

Mcgyver
I checked out your link. Very nice work indeed!

My burner was simply a scrap block of brass with the most of the inside milled away,
a brass plate for the base, a small piece of brass tubing for the spout and a turned,
vented brass plug for the filler.

I used a candle with the center gouged away to make a smokey flame to soot up the
block before soldering. Then I cleaned and fluxed the areas I wanted the solder to
flow to. I still got the over run you see in the first picture. I could see the flux running
there, but I was committed by then.

A lot of people would tell you I should have been committed long before then,
but that's a whole different subject!

Rick

 

[compound driver 2]

Hi
If your trying to contain the solder use an HB pencil to draw a line around the area to be soldered the solder wont flow over the pencil line.

Scouring powder works well to remove the flux followed by a dip in citric acid. The acid will blacken the solder but this wipes off wit scotch brite.

For teh work being done here the best flux is Bakers Fluid unlike the paste fluxes Bakers will partly clean the bress as it gets hot. thats no exscuse for not cleaning the joint first.

One thing to remember is dont use emery cloth to clean joints that are to be soldered. The cloth has a small amount of grease in it and the emery will embed in the brass. Wire wool is the choice most times follwed by a degrease.

Heat the work not the solder. Heating the solder can give you false runs were the solder is fluid but the metal is not hot enough for the proccess to take place.

Cheers kevin

 

[mklotz]

For soft soldering jobs, I've had great success with plumber's solder paste. Available from places like Home Depot, it's (apparently) finely ground solder suspended in a sticky liquid flux.

It can be 'painted' very precisely onto only the area to be joined and will remain in place while heated. Unlike working with wire solder, you're assured that there will never be too much solder. In addition, since it's applied before heating, you can be confident that it will be where it's wanted.