Tools, Glorious Tools! #3 - Home Shop Foundry: The Furnace

Hey Folks,

By request the full detail on my furnace, please enjoy!

Cheers,

Chris.

________________________________________________________
A very special thank you to Patrons:

Glenn Trewitt
Mike Manfrin
Christopher Warnock
Guy Loughridge
Charles Frodsham & Co.
Peter John Richardson
Adam Slagle
Tim Bray
Dan Keen
Samuel Irons
Sean Kuyper
Matteo Neville
Daniel Cohen
Larry Pardi
Olof Haggren
Stassinopoulos Thomas
Florian Ragwitz
Andrew Smith
Bernd Fischer
Sam Towne
Jack Cause
Jeremiah G. Mort
Andre van Soest
Matthew Middleton
Thomas Veilleux
Dave Seff
Robin Haerens
L'Enfant Watch Company
C. A. Patrick Voigt
Mark Coburn
Bogdan Dan
Steven R. Crider
Gary Levario
Pete Askew
Jeff Armstrong
Rudolph Bescherer Jr
Robert Petz
Ralph McCoy
Jim Popwell
Kaedenn
Bradley Pirtle
Alan Carey
PaxAndromeda
John A McCormick
Thomas Eriksen
Michael Hardel
Tim Ball
Dominik Rogala
Xanadu-King
Eric Witte
Peter
Grant Michener
Jonathan Teegarden
Steve Hossner
RuKiddin06
________________________________________________________

Furnace Dimensions:

Outside shell constructed from 0.8mm mild steel sheet, with spot weld joins. For the inside insulation details, refer to video.

Lid - Outside shell 330mm x 50mm, with a center hole in the top of 100mm OD. The actual OD of the exhaust hole is further reduced to approx 60mm after application of insulation/ITC100.
Body - Outside shell 330mm x 230mm. Central cavity has diameter of approx 220mm after application of insulation/ITC100.
Base - Outside shell 330mm x 90mm, with diameter of cast channel = 220mm. The Plinth OD is 150mm, giving a channel width of 35mm.

Regulator

Brass Fittings for the Reil Burner

Steel Fittings for the Reil Burner

Refractory, Insulation & Crucible

References:

... and many more builds that I've seen but don't recall precisely where - thank you!

[zuthalsoraniz]

I think at least part of why that lump of mortar works to hold the flame in place is because it makes the main jet of gas detach from the bottom of the furnace just behind it. This creates a turbulent recirculating zone with low flow velocity just behind the lump, where the flame can stay despite the main gas flow being faster than the flame velocity.

It's a somewhat similar mechanism to how the flame holder in a jet engine works.

[bellowphone]

I just felt a tremor rock the foundation of my world: I heard Chris utter the words, "I had a metal fabricator make... "

[paulthebaker]

I really like how your design removes the need for an extra tool. By being able to lift it from the side, you don’t need to take the extra step of rearranging tongs. The best part is no part.

[larrybud]

Clearly the next step is to start digging holes in your backyard and mine and refine some ore! Good stuff!

[dl]

With the epoxy, I suggest leaving the excess on the paper beside the project. That way you can check the paper for hardness instead of the item being bonded.

[plasmarc]

There are few things to make it even better.
On my furnace I added a metal grill to preheat the metal scrap and use up the exiting heat to remove the moisture prior to charging the crucible. Also, my crucible is lifted from the base on a small metal "stool" made from rebar to prevent the loss of heat through thermal bridge to the bottom. This thing with the lump of mortar is very smart.

[charliewynn]

Low thermal mass is a huge pro.. don't have to wait days to bring it back inside to store

[Craftlngo]

Since you are capable to melt copper, it could be interesting to make your own aluminium bronzes. This stuff is expensive but an amazing bushing material and resitant to corrosion in saltwater

[Tsl]

A tip about the burner -- with sheet metal ("flare") wrapped around the tip of the pipe, the, I think turbulence from the step, as the flow goes from pipe ID to OD to air, makes an effective flame stabilizer. I've built burners of this design which are stable down to a trickle of propane -- comparable to the flow rates of residential natural gas stoves, but with much simpler (read: not an array of holes) geometry!

So, a strip of sheet metal, long enough to wrap around the pipe OD, and about two ODs wide, so it sticks out about one OD. You can use spring force alone to hold it in place, or hold it with a hose clamp. It will of course get very crispy inside the furnace; a tight-fitting tuyere serves the same purpose.

[PPYTAO]

Molten metals are so beautiful. A mostly pure element holding a huge amount of energy, losing it rather rapidly and changing forms.

[timhyatt]

i've watched a lot of melting/casting channels. the ability to lift off the main body and then pick up the crucible using the same tool you'd use to pour with seems like a huge time/effort saver!

[steamfan]

Very nice build, one place to find smaller amounts of furnace building materials is at a pottery and ceramics supply. They usually have everything needed and are used to catering to hobbyists.

[Senki]

This kind of high quality no-nonsense description of a furnace build is perfect for hobbyists looking to learn

[zarathean]

alternative design options, mine has a T above the reducer and the gas pipe goes in line from a hole in top, i use a MIG tip for gas port and on side of T i have metal flaps to regulate air. having a bell reducer for a flame keeper also helped mine maintain velocity

[Masterman]

The other thing is since the furnace will wear out, having a lot of leftover supplies to make more is a good thing. It is also recommended for melting at higher temps to put cardboard under the crucible to prevent sticking.

[Roblecop]

BigStackD has a whole channel based around casting from a home furnace. It was cool to see your furnace set up compared to his. I think the 3 piece design does have a few benefits

[jamesbarisitz]

I made my own water glass using 100% silica gel kitty litter. Add it to perlite potting material with sand. Cheap and great casting material. It even makes great briquettes for the propane barbecue! 👍 😃

[utooth]

One addition you may like to look into is a flashback arrestor.
Great video as usual. 👍

[balaclavabob]

Give Big Stack D a call . He'll put you right on the finer aspects of pouring cast metal ... namely, opening beer and saluting the flag, seeing what the boys are up to and the esoteric choice of socks .

[viceskyre]

Gosh if I may?

I used to cast precious metals as as a precious metals fabricator (bullion, bars, and blocks) and some things that may help your cast are:
- put a layer of carbon on your moulds with a yellow oxidising flame after you've heated them up to evaporate moisture. You'll be able to then just tip the metal out immediately after it is set. Your moulds will live longer.
- if you can - which I know is not really possible on your own with a 2 handed pour unless you have a second person - but keep a flame on the molten metal at all times. In the crucible, pour stream, and mould; and keep it on there as it sets. You'll get a better result with very little sinkhole.