Crucible Furnace

[BOB BLACKSHAW 1Participant @bobblackshaw1]

Hello, I was at the Old Warden steam rally today and an exhibitor there made brilliant working Beam Engines, he cast all his own materials Brass and Aluminum from scrap items.

These Crucible Furnaces are quite cheap but I meant to ask if he used a electric or gas, does anyone know which method of heat would be more economical for these 3 kg max furnaces.

The method used to cast square bar is four strips of steel clamped together, round I would imagine steel pipe.

Anyone here use a Crucible Furnace ?

Bob

 

 

[noel shelleyParticipant @noelshelley55608]

YEP ! I’m here. I would use gas ! You want your melt ready to pour in 15 – 20 Mins and 3Kg is not really big enough. Cooking slowly with electric for alli or brass is bad. There’s lots on y tube but much of it quite dangerous. I will be at the midland show for 3 days, come and talk to me. I will be giving 2 talks,Thursday and Friday. If you want success then economy should not be a criteria.  Good luck. Noel.

Ps The following was filmed at the midland ! Y Tube,   Dubious Engineering – melting brass in a spin drier

[John HinkleyParticipant @johnhinkley26699]

Bob,

John “Doubleboost” Mills posted a couple of video reviews on the 6Kg and 12Kg Vevor furnaces about a year ago.  His reviews are no flannel, down-to-earth ones.  If they’re no good, he says so – in his own inimitable way!

Here’s a link to the 6Kg one.

And another to the 12Kg one.

He uses gas – propane, I think, to fire these up.  They seem to work OK.

John (not Mills)

[BOB BLACKSHAW 1Participant @bobblackshaw1]

Thanks for the replies.

Interesting videos, like to have a try at a bit of casting. A chap down the road from me now restores classic cars but originally was a casting engineer for Allan`s in Bedford, he’s done some work on my old MG .

Bob

[John PParticipant @johnp77052]

You could try on here
https://www.academia.edu/115318929/Building_A_Gas_Fired_Crucible_Furnace

free download David Gingery crucible furnace.

I made one of these a long time ago 1990 i think
but used heat resistant bricks for the lining ,gas fired with propane  electric blower  .

This is the only photo i could find holds maximum A8 crucible
about 20 lbs cast iron /brass ,you need a fair bit of
other stuff to go with it moulding flasks , sand , tooling
protective clothing .

https://www.artisanfoundry.co.uk for foundry supplies.

You can use play pit sand for the molds and sodium silicate
binder they sell it or you can make your own with gel
cat litter and drain cleaner (sodium hydroxide).

John

[BOB BLACKSHAW 1]

On BOB BLACKSHAW 1 Said:

Thanks for the replies.

Interesting videos, like to have a try at a bit of casting. A chap down the road from me now restores classic cars but originally was a casting engineer for Allan`s in Bedford, he’s done some work on my old MG .

Bob

That’s where I hail from – not Allans itself but about a mile down Old Ford End Road into Honey Hills and Wingfield Close.

[BOB BLACKSHAW 1Participant @bobblackshaw1]

1. Thanks for the information John, they do look simple to make your own.

[noel shelleyParticipant @noelshelley55608]

For the price the Vevor item is a good way to get started, though it is easy to make your own furnace. The ceramic fibre used as the insulation is frail and insulating bricks are far better – mine has lasted 30 years. The skill comes in making things you need not just lumps of metal that whilst stock will not be so easy to remelt. The single most important tool you will need for success is a DIP PYROMETER. Remember that to pour into a mold the metal needs to hotter than just melted and for cast iron you will need more heat this type of unit will produce ! For brass you will be above the boiling point of Zinc and all the hazards that brings.  NEVER pour on concrete or slabs !  Good luck. Noel.

[jaCK HobsonParticipant @jackhobson50760]

I reckon it often doesn’t save much money (if any) to make your own. I think I’d go vevor or similar for a new big furnace or forge. Gas for larger castings.

Burners are simple to build, particulary forced air, but there is an art to getting an efficient natural air fed burner. For smelting, maybe a fine tuned burner isn’t so important as it is for forging, but consider Amal https://amalcarb.co.uk/amal-gas-injectors/propane-injectors.html which are the best of the best – really good control.

The 1-3KG electric furnaces are very convienient. They only just get to temp for pure copper… maybe not always… but it is rare to smelt pure copper and any alloy will melt at a lower temp. Ideal for making small billets of non-ferrous alloys or small castings. And you can use them indoors with care but you probably don’t want to pour significant castings (bigger than jewellery) indoors. You can use metal crucible in them as the heating element will touch and trip the RCDs in the house.  i use one as a salt pot for high and low temp salts for heat treating small items.

 

[noel shelleyParticipant @noelshelley55608]

NEVER SMELT IN DOORS ! Unless it is a proper facility. The slow speed at which most electric furnaces work will allow gas absorption and cause trouble with blow holes as the gas comes out of solution. Gas in this context means any gas, oxygen,nitrogen, hydrocarbons Etc.  Noel.

[Engine BuilderParticipant @enginebuilder]

Lets get the technical term correct. We are melting metal not smelting.

“Smelting is a process that uses heat and chemical reactions to extract a pure metal from raw ore (rock containing metal)”

[Author]

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