NEW FURNACE
This is my new furnace, it has been built to take up to a number 12 crucible. This furnace has been designed along the lines of the gingerly arrangement but there are a couple of subtle differences worth mentioning. The guide assembly utilizes ball bearings instead of the guide rollers, the lift arm arrangement has been redesigned to negate any offsets so no bending of the arms is required. I have used K21 insulation bricks available through Thermal Ceramics to line the furnace and coated the exposed surface with ITC100, if in Australia it is available at Pinches Alloys. There are a number of benefits of insulating in this way over using a castable.
1) These bricks can best be described as blocks of honeycomb, they are extremely lightweight.
2) They can be easily cut with a hacksaw or sharp knife and formed to suit the round shape of the steel barrel.
3) They are an extremely good thermal insulator, in fact better than Kao wool and without the exposure to Crystalline Silica.
The only down side to using these bricks is the temperature rating. They are capable of up to only 1170 deg C (2100 deg F) this is well below the melting temperature of some alloys I cast. To overcome this problem I have coated the interior surface with ITC100, this coating has the ability of reflecting a high percentage of the heat back into the furnace protecting the brick work. I have done many melts in this furnace and experienced only minimal cracking on the surface.
I can melt a fully charged number 6 crucible with Silica Bronze in 20 minutes with subsequent melts every 10 minutes.
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This photo shows the furnace in the operating condition. Sitting beside the furnace are a No 12 clay graphite crucible and a No 6 silicon carbide crucible. This furnace is portable, a handle can be inserted in the front and the whole show can be relocated.
The furnace can be separated as shown to allow removal of the crucible from the side.
A view from above showing the interior
The foot lever to the left allows the lid to be raised and pivoted to allow easy access and charging of the furnace
A close up view of the guide arrangement. I based this design on an arrangement from a bloke called Harvey Pennos. His furnace can be found on Robert Grauman's web page.
Lifting a large steel crucible out of the furnace. It was to large to use the split and lift feature of the furnace so some special lift and pour jigs had to be made.
Lift and pour technique
The pipe crucible which is equal to a #20 clay graphite crucible.
Its capable of around 12 kg's (26 lb) of aluminum
Lift and pour jigs
Pouring tongs for a No 12 crucible
Pouring tongs with a No 12 Silicon Carbide Crucible
Some of the different pouring shanks I use for No 4 and a No 6 crucibles
together with crucible lift tongs, metal tongs and skimmer for Aluminum.
The Aluminum skimmer is a kitchen soup skimmer I bought for a dollar at
the local Supermarket. Just remove the handle and skewer onto a piece of
1" Diameter round dowel for insulation. Throw away and replace when worn.
Pouring moulds made out of angle iron.