I've been interested in hobby casting for ten years or so. I remember avidly reading the build your own workshop from scrap series written by the late Dave Gingery . Until recently I haven't been able to try any metal melting due to lack of suitable space or free time. I also gained a lot of inspiration from Lionel's Lab Fortunately now the house extension is pretty much finished out attention has moved to the back garden and I have prepared a space that will be good for outdoor brazing and metal melting.
I had planned on building my own furnace but whilst browsing ebay one day I came across an auction for a Kasenit Natural Gas furnace with burner, crucible and tools.
The description was a little off in that it omitted to say there was results of a broken crucible stuck in the bottom. But it saved me making a furnace and burner from scratch. The furnace is extemely heavy it's made of steel and a concrete like liner! We were lucky enough to have a 150Kg hoist with us when we picked it up otherwise we'd have struggled. It's too heavy for two people to lift unassisted. Here's the name plate.
It reads Kasenit Bletchley Bucks. Serial number Z-8106, Pressure 6 WG, Drawing Number Z-5974.
I don't have a convenient way of getting Natural Gas to the back garden so I decided to run this burner from Liquid Petroleum Gas (LPG) or to be more specifically Propane Gas. Looking round on the web I found that the conversion would involve reducing the jet size but to how much?
I posted a request on the Yahoo HobbyCasting group. Luckily I got a reply from Ian Barker who had been through a similar process. He'd gone from the original jet drill size of 29 (0.136"/3.45mm) to drill size 39 (0.0995"/2.53mm) I've since had some correspondance from Peter Chadwick who is using a 0.9mm drill. The bigger the hole the hotter the burner runs and the quicker your metal melts. Fast is good! The burner will work well with this range of jets because it has and adjustable sleeve which alters the amount of air drawn in with the gas. I've started with a small jet (~1mm) but intend to try some larger jets when I can. Here is the original Jet
I had a selection of small brass jets so drilled and tapped the original to take the smaller jets.
Here's a top view compare to the original
You'll have to excuse the crappy photo quality I've now got a much better camera so close ups should be easier. Here's the new jet installed in the burner.
The knurled aluminium cylinder is screwed in and out to adjust the mixture. With such a small jet I had to reduce the air inlet until you could hardly see the jet! Note the concentric rings turned into the adjuster these make it easy to note what settings you are using. You also get a good view of the adaptor used to attach the LPG hose.
Here's the whole burner assembly. Note the flange with two holes, this is used to bolt the burner to the furnace.
I'm currently running the burner off a 0-4 Bar adjustable regulator set to about half way so hopefully around 2 Bar. This is hot enough to melt aluminium in small quantities. I will probably add a shut off valve after the regulator rather than use the bottles valve.
When we picked up the furnace there were two fire bricks in the bottom held in place by about two inches of Congealed Aluminium. I guess a crucible had broken at some point. I had to clear this mess out as it was absorbing a lot of heat and preventing the hot gasses from circulating correctly. After about an hour of heating and prodding with various implemented I managed to melt out enough of the aluminium to remove the bricks. This left enough space to prise out the rest of the alumimium. Here's all the mess which came out of the furnace.
I don't have a view with the mess inside but heres the inside after cleaning.
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