Soldering brass

[Clint Sharp]

I know bronze is fairly easy to work with, what are the pitfalls with brass? I've been told it was fairly straightforward.

Lost frog? OK, I'll go Google.

[Andy Dingley]

Bismuth is the safe replacement for lead shot. Nor do I see what this has to do with tin.

[Andy Dingley]

It's straightforward to "cast" it, harder to get a reliable pour in such a long thin section as this.

It also depends on your brass alloy. It's easier if you have something that can be taken to a higher temperature (without dezincing) and remains fluid to a lower temperature. Tin bronzes will generally be an easier route to this than zinc brasses.

Frog-feet cast in silver, but missing out the usual intermediate moulding steps. Burn-out is a bit stinky...

[Clint Sharp]

In message , Andy Dingley writes

Ahh, I see.

Longer working time essentially, contact with the mould cools it to a point where it's no longer free flowing or even solid, could you not pre-heat the mould or even work up a spin casting system I wonder?

Personal preference would be to make the walls thicker

Nice, think I'll pass on that one.

[Matty F]

The sample was cast. Perhaps it was cast upside down like this:

that the middle part of the hinge is thicker than the wall so the pattern would not extract easily: 'd prefer to cast it. I'm still waiting for a photo of the real original box. If I could get a solid block of brass that size I'd just mill it out.

[Rick Hughes]

why silver solder ?

[Rick Hughes]

If you want strength then bronze weld it, better than soldering.

[Andy Dingley]

Almost certainly gravity sand cast, by someone who knew what they're doing, probably in greensand. Although it's even castable in an open back mould, these were cast industrially by using a core (a separate shaped lump of sand, laid into the mould after moulding and before casting). If you're capable of doing cores at all, something like this is easier to cast with an added core than it would be to use a hollow- box pattern and to get clean pulls from the mould every time.

The big difference, in terms of pouring success, is that they'd gravity cast it and use quite a deep mould box to do it in, with a big pour. The inlet gate would be deep, so the pressure in the mould cavity is high and you'd get good flow into the mould before it chilled. Easy if you're tooled up to do deep moulds and handle the excess material for a deep gate. Most of us though are handling small crucibles and need every spoonful of the melt.

[Matty F]

Yes we seem to have all the gear for that. I'll have to learn how to use it over the next few weeks.

I have a variety of brass bits here.

The box is cast and is between 3 and 5 mm thick. I have plenty of 5mm brass plate and 0.5mm sheet (i.e. too thin), and some 2mm and 3mm plate. The supplier has sheet in 1 metre x 2 metre sheets, i.e. rather a lot!

[Matty F]

I wasted lots of time reading about =93Who took my frog?=94 (by an autistic teenager):