Small Furnace

[Foccacia]

Hi
Does anyone have a set of plans or pictures for a small furnace, fired by LPG. The alloy I'm using melts around 327 degrees C.

[eskimo]

follow this to the links or the links that appear in this that link that are elsewhere

http://www.woodworkforums.com/f65/anyone-casting-foundry-work-135610/

or you can try this one

lots and lots out there

[RayG]

Hi
Does anyone have a set of plans or pictures for a small furnace, fired by LPG. The alloy I'm using melts around 327 degrees C.

Hi Foccacia,

A small electric or hot plate or gas ring should do that. Depending on how much material you want to melt of course.

Regards
Ray

[4-6-4]

The last time I talked about furnaces I got a negative reaction. The drawing recommended has some drawbacks. The overall dimensions OK but it looks as though it is made out of firebricks. These are heavy and I am not sure if they are easily found. The circular lay out with the burner coming in at an angle is good. This promotes a swirling action around the crucible. There has to be a hole at the top to let the heat out. I used as large a crucible as I could lift out of the furnace. ie 15 Kilos of Aluminum about 600 degrees and Gunmetal, Silicone bronze at about 1200. Now we come to the nitty gritty. I used a Drum from a reseller and I lined it with stuff called Caowool. You can purchase it from foundry suppliers in the form of a 25 mm blanket. It is then wrapped around the inside of the drum.This is a heat reflective material which will cut down on your time required to melt. It can be cut with a knife and there is a liquid available which puts a crust on it after the first firing I used a lump of firebrick to set the crucible on while heating and the appropriate tongs are needed to lift the crucible out. I cut the top of the drum off to use as a lid and packed it with Caowool. A largeish naturally aspirated torch I am assured will work. I user a vacuum cleaner exhaust to provide the wind. When working with raw Caowool I wore a dust mask. You will also need a heavy pair of gloves or mits when handling hot metal as well as all the other safety gear.
What metals are you melting and the other vital point is what are you casting in ie green sand or chemically bonded sand. I had my own non ferocious foundry and have had experience in Iron work as well. Give me more information I may be able to help you
Yours 4-6-4

[Foccacia]

Hi all
I have tried the gas ring and the heat loss won't allow the alloy to melt in the crucible. The alloy is 97% Tin, 2% antimony and 1% copper. It is sold at jeweller's supplies however I got mine from Northern Smelters in Queensland (much cheaper). I am only melting approximately 600g at a time and I was surprised that I couldn't get enough heat from the gas ring. The crucible is a commercial ceramic item, sold by a foundry supply place in Padstow and since it is a silicon carbide compound, it will act as an insulator from the heat source. Maybe I'm trying to be too technical as a colleague suggested purchasing a cast iron pot from the camping supply place and sticking it on the gas ring. I want to take this sort of work on as a hobby so I'm looking for a good long term solution.
Cheers all
Foccacia

[RayG]

Hi Foccacia,

The design that 4-6-4 describes is the way to go, what you want is low thermal conductivity, and low thermal mass, a few layers of Kaowool (or Cerachem) with an infra-red reflective coating on the inside. No sense wasting gas heating up all that heavy dense firebrick.

Even though you don't need it for what you are doing at present 327 C, building a better furnace that can do bronze and brass is a better approach for the longer term.

Regards
Ray

PS Also, have a browse around BackyardMetalcasting.com - Lionel's Laboratory :: Index (http://www.backyardmetalcasting.com/forums/index.php)

[4-6-4]

I hate to be a sticky nose but what is the medium you are going to pour the melt into. Usually melting the metal is the easy part its usually the mould that causes the most problems be it lost wax or sand. If its sand I found stuff called Petro Bond to give a good result. Its an oil based mixture and I used it as a surface coating on sand moulds to give a good finish. As an aside there is a bloke in the Live steam world in NSW named O,Brien who was building a number of 3 truck Climax Locos. The Climax had a strange spiral bevel gear which the shafts were not at right angle, to provide a drive to each axle. Petro Bond was used so that the bevel gears were used as cast. Mind you the wood pattern was pretty crash hot. Yours 4-6-4.

[Foccacia]

Hi
I am casting into a mould made from a 2 part silicone rubber - good release and reusable. I've coated it in graphite which allows for a good release and a slight tarnishing of the surface of the pewter.
I genuinely appreciate all of the advice that I have received and will receive in the course of this project.
Cheers
Foccacia

[QC Inspector]

A friend and I used to shoot muskets and made our bullets using a weed torch/roofing torch aimed at the side of the cast iron crucible, or maybe it was a cast iron pot, :rolleyes: to melt the lead. I think the same would work for your pewter if you want to keep things simple.

Pete

[rusty steel]

I remember years ago I helped a mate make some extractors for a Ford V8 and we used a forge made from a truck rim filled with coke and we fed compressed air into it. It got very hot . I dont remember the design details but someone on this forum probably does. Russell