About time I'm getting around to writing this... had this thing for a little while now :o Darn this laziness...!
Foundry setup. Tongs to the left (made them specially for the furnace, well actually I fit the furnace to the tongs, so I don't have to make it bigger than I have to!), furnace, lid, gloves, cut milk jug of bronze scrap, extra crucible (still caked with aluminum from its first melt so I'm not using it here) and propane tank. Not seen: monster burner. Would I have it [heated] any other way?
Down inside the furnace. You can see I've already burned it out, twice... the first burnout (way too fast of course... so sue me) and an aluminum melt, gathering up fine scraps in the #6 SiC crucible and pouring a few ingots. Furnace body is constructed entirely of LWI-26 castable, while the lid is a rammed mixture of ball clay and vermiculite. It insulates very well, but shrinks a lot when it gets real good and hot (probably 2300°F around the vent hole), leaving massive cracks. Some furnace cement filled this in, putting it back in pristine condition at the moment I type this. Oh, and that's a #4 clay-graphite crucible in there I picked up from a foundry guy for $15...(gloat? What's a gloat?)
Lighting up, the flame spirals around inside. The tuyere gets a good white heat going after half an hour, nearly melting the LWI-26!
Standing in the basement doorway I watched the tuyere glow... it's only yellow here. Doesn't look like there's much gas flowing either, for these melts I crank it up to 35PSI (or whatever it maxes out at) and that gets it singing... Note also the firebricks on the lid - good idea, bad execution. The heat, being deflected sideways, warps the lid metal temporarily, so scratch that.
There's the white heat I spoke of! :D The bronze scrap is about 1500°F right now. Still a bit before it melts.
Fifteen minutes later, I've melted all the bronze and made my additions of slag, and zinc (carefully!). A few more minutes and it is superheated sufficiently. Then I poured it. As you can see, it was a little more exciting than the textbook aluminum reverb melts, not to mention neat looking because it was fuming (more than 15% zinc). Got to love those calm blue to green flames!
And here ya go, one complete(!, having failed twice before in aluminum) cast bronze trivet. I later melted it because I didn't want to ruin my files (and you need *sharp* files for bronze!) on all the stuck sand.. I think I poured this one too hot. Later ones proved quality:
This is another one. The pattern is the center section of the above pattern, cut from the second failed aluminum casting. The aluminum pattern releases very nicely from the sand, getting those utterly clean parting lines. In fact, for a few inches on one side, you can't even feel the parting line!
If you are interested in one of these (large (10" square, $30), medium (7" round, $20) or small (copy of cactus or mining wagon, neither are my design; $10), please send me an e-mail! Choose your metal: zinc, aluminum or brass - for finish, I can do bare metal (zinc, aluminum or yellow brass), painted (pick a color) or various patinas (blue, green, brown, coppery, etc.) on the brass.