Some of the grey iron castings required annealing as I ran into a few hard spots during machining.

For $50 I picked up what was left of large pottery kiln and then repurposed the fire bricks into a smaller design shop built oven.

I welded up a simple frame from 3/4″ angle and flat stock, made a door out of leftover sheet metal and attached it with two heavy duty hinges. The fire brick was hand cut to fit the frame and door and then channels were carved for the high temp Kanthal heating element. Refractory cement helps hold things together.

The old kiln’s analog control box was gutted and cut down to house the new digital Inkbird PID temperature controller and solid state relays. The oven runs on 240v and two 15amp fuses were installed for circuit protection. One toggle switch turns on the main power and a secondary switch turns the coil on and off.

A high-temp thermocouple was placed in the top center of the oven to relay real-time temperatures to the PID controller which regulates power to the heating elements.

A coat of red paint finished off the oven and after installing some high-heat door gasket material, it was ready to start “cooking” some cast iron.

This thing heats up FAST!! During a test fire, it reached a target temp of 1500° in less than 20 minutes and during actual annealing, the oven held high temps for nearly 12 hours with castings inside and the door latched closed. All in all, the oven worked perfectly as it is vital that gray cast iron cools very slowly after reaching approximately 1450° and holding for one hour. Almost like baking brownies!

The annealed castings now machine like butter.