I have a pin hole in a brass instrument. The usual 2 ways of patching it would be to put a small brass patch on it or melt a tiny bit of solder into it. The patch works well but it is an obvious patch, solder works well but it is silver and is also obvious. I know silver solder will do the job and looks sorta brassy when done but there is too much chance of melting the pipe.
"brassbend" wrote: (clip) I know silver solder will do the job and looks sorta brassy when done but there is too much chance of melting the pipe. (clip) ^^^^^^^^^^^^^^^ There are silver solders that melt at substantially lower temperatures than brass, so you should be able to do the job without blowing a hole. If you are inexperienced at this, get some brass sheet of similar weight and practice. When you get ready to do the actual repair, you can use a piece of the practice brass to back up the hole for extra insurance, if you feel you need it. Don't put flux around the back of the hole or on the backup sheet. You will probably have to do some filing, sanding and buffing on both sides to make the repair blend in.
Or, if the piece is of high value and you're really worried about messing it up, take it to a professional. They'll have the right tools and the skill to do the job (and they should have insurance to cover your loss if they screw it up). Ask for references.
you can get a dull brass color, black, green, copper. a good shiny brass color is pretty hard to find. most stained glass shops will advise you to use paint of some kind on brass. i believe michaels has a bright shiny brass colored paint pen.
I AM the professional : ) I have the right tools and the skill : ) I have also consulted with the highest pros in the instrument repair business and got a little information. I am taking it here in hopes that someone not in brass repair would know something we don't.
If you have some scrap available to do a test on, I'd try a local welding shop with a TIG welder, you can use the same alloy brass wire or strip as filler.
You need someone used to doing delicate work, so the weld puddle is just big enough to do the job - I have a friend who fixes injection mold cavities for a living who can do itty bitty beads. And the beauty of TIG is lots of control.
Then the color match shouldn't be a big issue (except for the brass alloy mix getting a bit out of balance because of the weld puddle) it's more a matter of grinding and buffing the repair flat again.
Jewellers use solders in various shades of gold but these are hard rather than soft solders and so might not be suitable for the application. I'm afraid that I don't have my reference books to hand to look up the melting points.
Where on the instrument is the hole? Could you patch it from the inside with brass or copper shim? You will need to get a dremel or similar in to clean up the surrounding area if you go down this route to get the solder to take but it might be possible, I've seen this method used to repair valve ports, apart from the cleaning the difficult part is holding the shim patch in place while you solder it, this usually involves making up some sort of 'hairgrip' spring to hold it in place. K&S material centres (hobby stores) do a small pack of various thicknesses of shim.
Nope. TIG is used in a few application in the instrument industry, but the fabrication process is really designed around it - often the workpiece is water cooled. Instrument brass is just too thin (.014"), and the zinc likes to vaporise out of it with some sputtering - had really bad results on stock twice that thick. Once place that uses tig starts with a double thick workpiece, no filler, and a water cooled mandrel, then grinds the result down.
I'd be hesitant to use soft solder for patching - it's for large area joints not for structure. But one of the lower temperature hard silver solders with a wide plastic range, and a really really tiny flame might be an option. Unfortunatley the low temp hard solders - 56% silver, etc have a silver rather than brass color. The brass colored ones are mostly high temp, unless you get one with cadmium in it.
If it's in cylindrical tubing I'd try to remanufacture the part. In a critical taper like a leadpipe, I'd want to replace the entire section. Only in a bell section or possibly bell branch would I be likely to try a patch.
I had wondered if solder would plate. Thanks for the info. At this point I am trying to make a solder out of powdered brass. I haven't got it right yet, the powder is indeed melting to the tube but each grain of powder IS NOT melting to its' neighbor. The repair looks jagged. LLB