Annealing Kiln — Adam Jablonski

THE KILN

I was discouraged by the price and yet the seemingly simple design and operation of even the smallest kilns so I built my own!

I wanted to expand so I bought a hotter oxygen/propane torch, built a small kiln and set up a workbench in my apartment. This allowed to to make larger beads and expand into borosilicate glass to make marbles and pendants.

Here's a few pictures of the kiln.

Materials:

2300 degree firebrick
1" x 1" angle aluminum,
20 gauge aluminum sheet.
Aluminum rivets.
1/4" threaded rod, washers and nuts to reinforce the roof

The total cost of the kiln was around $230.

Kiln Mockup

I cut the firebricks with a handheld wood saw and did a dry fit to make sure the pieces would fit together. Fire brick is extremely easy to cut but produces a lot of dust. The trick is to design a kiln that maximizes the number of whole bricks used to minimizes cuts and seams needed.

Fitting the Encloser.

Making sure the aluminum enclosure fits well. The legs ensure airflow can reach the surface it is sitting on. Aluminum was chosen because it was easy to cut and drill with the tools at hand.

Fitting the Encloser.

Fitting the Top of the Enclosure.

I put the element in the roof of the kiln. I wanted an even heat far away from the work on the floor, I'm not sure I would do it again this way. Kanthal expands and sags when heated which makes attaching it to the ceiling of the kiln a challenge. I used pins made of kanthal wire pressed into the brick to hold it in place. A better solution is to cut a groove in the walls of the kiln and embed the element there or sleeve the element in fused quartz tubing and hang that from the ceiling to eliminate sag.

Waiting to Attach the Roof and the Door.

It's not the prettiest but it worked well. I look forward to using it for more than just glass as well like burning out molds for lost wax casting and maybe small clay work If I can fire it to temperatures hot enough. I used a 9 amp kiln element made of kanthal wire designed for another kiln on the market of a similar size.

THE CONTROLLER

The controller was also built by myself with a PID temperature controller found on ebay, a K type thermocouple, and a 25 amp solid state relay. The project box was from RadioShack and the total cost was around $60. It doesn't have some of the features of other more expensive kiln controllers such as programmable ramp/soak and annealing settings but it can hold the temperature well and the PID controller can easily be upgraded in the future.