Sunday, 20 January 2013
Help me...I'm Melting
So todays adventure...I managed to get my homemade furnace up and running and melt down a small amount of aluminium scraps and pour it into a crude sand cast to make a vaguely cylindrical bit o metal..
So above is the shot of my setup! Its an old paint tin into which I cut a hole and for a small tube to go into (about 15mm outside diameter about 12mm internal). In the bit of the tube that is inside the furnace I drilled a series of small holes about 10mm apart in a line to allow air to escape the tube. The paint tin was then lined with a 25-30mm depth lining of fire cement ( a lot of online guides for furnace making have quite complicated refactory mixes to line furnace but for a small one like this about 8quids worth (a large tub) of fire cement will do the job).
I did the cement lining of the base first up to the depth of the hole for the air tube, which I then cemented in place and then built up the sides.
On the end of the air tube is a cutoff plastic bottle top as a kind of wind funnel and then place in fron of the funnel is a hair dryer (set on cold..warm air is not as good and it would burn more electricity anyway). The piece of terracota pot on top was acting as a slight lid to try and keep as much heat in the crucible as possible. The heat is supplied by lighting a small fire of some broken down pieces of charcoal briquettes, incidentally the charcoal sold for bbq's will work (it's what I used today) but they say that better quality charcoal will burn hotter for longer.
I used a steel can as a crucible and after a while heating and adding aluminium scraps I poured the results into a crude sand mould which was a small tin filled with builders sand, very slightly moistened so it held shape.
Here's the result! Its vaguely round and although looks rough (due to the lack of resolution offered by building sand..oh and that I just pushed a lighter into the sand to make my mould!)..it would be round enough to put into a lathe to make something from...I WANT A LATHE SO BAD!
Next steps for this at some point are to buy a small amount of casting "green" sand and make a cope and drag (like splittable cases for sand moulds) and get casting some more interesting shapes.
If you're interested in casting metals please don't just read this...read as much as you can on the web as there is lots of safety stuff you need to follow...like don't wear any synthetic fibres as if you are splashed they will melt and stick....EEEK