If it's a forge I'd like to know what he's made the grille out of! I think it's an eel trap. They enter through the small hole at the bottom then get confused by the squares at the top and sit quietly until you eat them........
By Golly it's a smelting furnace made from scrap bits'n'pieces salvaged from work, total cost probably $80
The refractory material is made from clean, washed river sand and plaster mixed 3:1.
The outer steel body is made from a bit of thick well casing. The rest is just bits and pieces and about 12 hours work.
I'll need to let the refractory material dry for a cpla weeks before I attempt to temper it in stages at increasing temperatures. This gizmo will run on BBQ briquettes and gentle compressed air which should be sufficient for smelting aluminium. When I attempt brass I will likely need to introduce some propane gas.
The astute observer will of course notice that the air in-feed is pointed off centre to the inner chamber, this is to get a bit of a swirl or votex thing happening with the hot air.
Useful tool for getting to the bottom of an "overheating" engine scenario when the gauge reads hot but the engine may not necessarily be hot. Shoot it with this and see what's really going on [emoji106]
Given the high fire danger conditions in Brisbane these days I have been hesitant to fire the new furnace up for fear of torching the entire neighbourhood but while my neighbours were at work today I gave it the beans. I discovered that it would be way too slow without LP gas so I bored a 30mm hole in the plenum and installed a Gas torch to compliment the compressed air in-feed.
Bonza, it got up to 700 degrees in about 1.5 hours which was hot enough for the first go (next time I'll go to 750 or so) The first run gave me a dozen muffin shaped aluminium ingots.
What impressed me the most was that once the paint had burned off the plenum and other impurities were burned up there was no smoke and no embers, just clean heat.
So I fired her up again today and kept up the temp for 4 hours without any problems. I discovered that it takes 1.5 hours to get up to max temperature for the first crucible full of molten metal and a further 25 minutes to melt the next batch. I'm not too sure how accurate these digital thermo devices are but it looks like I got close to 849 degrees though I'd prefer 900 before I do any sand casting if I can get it, time for some fine tuning methinks.
My crucible holds 1.5 litres and that will be big enough for me for a while, I should have some fun with that. I now have a bucket full of aluminium ingots ready for what comes next, whatever that is.