Building a Propane Forge

Building a Propane Forge Part 1

A couple of months ago I decided to attempt building a homemade propane fired forge for casting aluminium. The hope is to use scrap aluminium and recycle it into blanks and castings to be machined using my lathe or milling machine. I know from the outset that this will be a difficult project as I have a lot to learn in the way of metalworking and DIY skills. Hopefully by the end of it I will have a usable forge and have gained plenty of useful know-how and hard learned experience!

I decided to use a design by a YouTuber called Myfordboy (his webpage is here). 

His exact designs can be found here.

Laying out the sheet to roll the outer steel shell for the refractory. I picked this sheet up a local sheet metal supplier for about €10

Outer Shell Rolled Cutting the sheet metal was tough work using a hand shears, even though it was only 0.8mm thick!

Inner Form Rolled

Outer Form with plywood sheet to hold its shape.  Not a perfect barrel by any means but an acceptable first attempt.   

More bracing to make it rigid to hold the refractory 

Refractory cement ready to be poured. This cement is rated up to about 1700°C and so could in theory be used for melting iron. The first attempt at pouring the cement ended up being a disaster. The weight and hydrostatic pressure of the cement was sufficient to detach the wood form from the base resulting in a large flood of cement. Luckily with the help of my Dad we were able to quickly rejig a more sturdy base and re-pour the rapidly curing cement!

Burning out the wood base of the furnace and curing the cement.

 Disaster! Remnants of a steam explosion! The temperature must have raised too quickly causing an explosive  buildup of steam behind the inner shell. The furnace made an almighty "pop" and cloud vapor after the explosion. 

Inner form removed

Damage from the steam explosion. The inner wall has had its top surface blown clean off. I think that the large structural cracks are in fact due to rapid cooling - I didn't keep the furnace cool and wet enough during the setting stage. This is a valuable lesson for any future designs.
I was able to touch up this face and the structural crack with some more cement.

Part 2 to follow...!