How to fix cast brass?

The other night I stole off to my shop to try and get in an hour of work between when the kids went to bed and when I needed to go to bed.

Ended up dropping a cast brass buttplate that was 3/4 of the way inlet. Of course it factured. it did not break, but the bottom inch of the plate is bent and there are factures snaking through it about 1/2 way through. I was able to bend it back into shape, but the piece is clearly deeply compromised.

Can this be fixed? I tried silver solder, but all the flux I put in would not entice the solder to flow into the cracks. I also tried brazing rod witout much success.

I have bought another butt plate. I would still like to figure out how to fix this though, given that the stock has been cut for the broken plate, and the inleting is almost done.

I hate working with brass. Its a shame that it looks so good and right on an early flintlock rifle.
Zach

Very weird that cast brass broke from being dropped. Maybe it is a bronze alloy. Let me ask whether it was wax cast or sand cast. Sand cast is normally of soft, ductile brass that would not fracture.

I don't think there is much you can do except get a new buttplate..

Very weird that cast brass broke from being dropped

Click to expand...

My first thought also. Strange.
What is the country of origin for your kit?

No idea.

I'm building this rifle for a friend of mine who got a collection of different parts, started the gun and never finished it. No clue where the butt plate came from, what it was made from - but I do assume it was sand cast as he is usually a frugal guy.

I did buy a new butt to replace it. But if I can fix this one (and the fix looks good) I'll use it for a rifle I'm going to build for my son. Otherwise, I figure this is at least a good practice piece now for fixing cast brass technique.

Zach

Youtube Brazing brass, may help you

As a caster of brass gun parts I can tell you that you will not likely ever fix that part. Providing that the caster knows what he is doing the only difference between sand casting and wax casting as far as quality goes is the surface quality. Few sand castings today are what I would call high quality. The surfaces of sand casting very according to the quality of the sand used and the experience of the caster. The casting you described gives me the impression that it may have been poured too cool. There are a lot of reasons a casting can do as you described but a good casting should not do that when dropped. That was a defective casting. Wax casting is poured into a preheated mold that has a very high quality surface. Sand casting is poured into a sand mold that is usually room temperature. Most of the time the surface of a sand casting will contain some pieces of sand from the mold making them hard to finish. From my experience most of the problems in casting but not all come from the metal used. A lot of sand casters use scrap brass. It is very hard if not impossible to analyze what is in a pile of scrap brass. Usually old brass fittings or cartridge cases make good brass. The proper alloy is called 360 brass. It cost a lot more money to do wax casting. The guilded casters in England in the 1800's used a special sand and made castings almost as good as the wax castings of today. Those English casters learned from childhood.

I wonder if you were to take the filings from cleaning up the brass and put them in the cracks with some borax and hit it with a torch if the filings would melt and fill the cracks...(I haven't tried it but I think it might work)

It might work if you were real lucky.

Don't forget, brass is an excellent conductor of heat and it is very difficult to get a tiny area of it to melt without melting a lot of material around the puddle.

Of course, when it melts, the brass will flow downhill (whichever way that is) so ending up with a welded crack without the whole area flowing away isn't easy.

It's more likely not true brass and made of added material than true brass. It would be easier and cheaper to buy new. If you want to play and learn with it, wear protection gear

Could he use the butt plate as a pattern and sand cast a new one ?

another thing that might work...use a small pipe cap held with vice grips held over a torch; fill it with the brass filings and borax, when it melts pour it where you need it (might file a spout in the pipe cap to help in pouring)

That might fill the crack but the poured in molten brass will probably not stick to the surfaces very well.

Take brazing for instance where brass is a common filler material.
The parent metal must be heated up to a temperature that actually keeps the brass in a molten condition.

If someone tries to braze parts together without heating them up to a temperature above the melting point of the brass filler, the filler will not stick in place.

It won't stick at all it will just run off. Might as well pour it on the floor

get another from dave keck, or Barbie chambers..... :thumbsup:
marc n tomtom