[Group Build] Back Garden Metal Furnace

The Build

This project is to build an ultra-low cost back garden furnance for melting metals such as lead, and aluminium.
The idea comes from Grant Thompson on YouTube:

We’re hoping for a low materials cost.

Build Participants

Please check this list to make sure your interest has been registered.

How to join in…

Registrations are now closed

The build will be run within a few weeks, more details to be announced.


You need an ominous countdown timer embedded into this post.

I’m in :slight_smile:

I am definitely in on this!

Sounds interesting :slight_smile:

Any plans on where this will be operated ?

We should be able to assemble them at GG, then go somewhere else to fire them up.

I think we’ll want to start crushing and stockpiling drinks cans so we have some material to use.

I have acquired (for some reason) an old hairdryer, we can use that for the air fan for now :slight_smile:

I have a steady supply of diet coke tins :wink:

Count me in for this !!

as for plans for where… how about stochastic_forest boot … his car has 2
of them I’m sure he can spare one (front or back…) !!! it’s a noble

It gets warm enough in the cabin already :slight_smile:

So one of the parts I wanted to improve on in this build is the crucible itself. The videos show a fire extinguisher cut in half to make a crucible, able to hold just under 500 grams of molten Aluminium.

Having spent a while checking eBay, I’ve found these ceramic graphite crucibles able to hold up to 890 grams of molten Aluminium.


I’d like some feedback on this choice of crucible, and any suggestions for a better alternative.

Looks interesting as a crucible Leo. I notice in the original video that the vertical sides of the fire extinguisher make packing the charcoal briquettes, prior to ignition, relatively simple.

I wonder if sloping sides might make that a little harder?

Clay graphite is presumably a better insulator than steel, might that impact on the efficiency or ease of smelting?

Waits for the hidden expert to raise their hand … :smile:

This is true. I’d like to talk to Reading hackspace about this stuff to see
what the implications would be using propane instead.

The graphite clay would be a better insulator, but would be much safer.

This looks like it will be an awesome project :smiley:

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I am interested and have some solid billets aluminium already.

Another update on the project:

I’ve been looking at the construction of the furnace itself.
While I’m still looking at using a 13 litre bucket as the base, I’m looking at something other than the usual mix of playground sand and Plaster-a-Paris. The best mixture I’ve found so far is the following:

  • Portland Cement
  • Silica Sand
  • Perlite
  • Fireclay

This is a mix I got from Back Yard Metal Casting’s “2 Bucks” furnace design, and looks to be a much more resilient and insulating than the sand and plaster mix.

With the furnace itself, and the crucible sorted, the last thing is the heat itself, I’ve been looking at various methods involving propane, which should burn cleaner and more controllably than charcoal.

With the deadline looming I’m going to be aiming to finalise the bill of materials and getting some feedback on it, sourcing the materials and costing it up.

So I think the easiest thing to use something like this 12 litre steel bucket.
Line it with the mix in my previous post, and use charcoal with forced air to drive it.

Need to find some smaller buckets to make the inside cavity. Saftey equipment is next up on the shopping list.

Hopefully will be able to get some pricing very soon and some dates for the build.

Hi All,

It’s been a while since a posted an update to this build, things have been a bit crazy.
I’m really hoping to get the build done in the (very) near future.

With that I’d like to post two options for the BOM for the furnace itself.

For Both Options…

  • 12 litre steel bucket
  • 5 litre plastic bucket
  • A bucket to mix the lining in
  • 5cm diameter steel pipe (about 30cm long)
  • 5cm diameter PVC pipe (about 2m long)
  • Air supply device (old hairdryer, fan etc.)

Option A

  • Silica Sand
  • Portland Cement
  • Perlite
  • Fire Clay

Option B

  • Plaster of Paris
  • Playground Sand

Both options will use the ingredients for the lining in equal parts, for a total of about 6 litres of mixture.
A drill mixer may be useful if available. For option B, a 25kg bag of sand and plaster should do all the furnaces.

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Don’t try this at home, folks :wink:

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I admit this project has been inactive for some time, but I have not forgotten about it. Things have been quite busy at work and the hacking time I do get I seem to always have a quadcopter or 3D printer to tend to. I’ve got a metal drum which I’ll post some pictures of soon which I think would make a good outer casing for the furnace. We’ve got the required piping etc, and some scrap Aluminium too, so now we just need the lining, safety equipment and frames/materials to moulds with.

Here is a video from EMF camp last year on 3D printed metal casting.

There is a handy summary of tips about 25 mins in and a website here.