This page is just starting out and shows my homemade kiln
that I built about 10 years ago for copper enameling. Also on this page
is a home built control system for temperature regulation. Currently
I am using the kiln for glass fusing and slumping.
The kiln in all it's rusty glory. I never got
a coat of paint on it. The kiln is constructed of 2.5 inch insulated
fire brick surrounded by 1 inch rigid fiber. The steel wrapper is
20 gage and pop riveted and screwed together. The counterbalanced
door is hinged at the bottom. Interior dimensions are 8.5 by 8.5
by 4.5 inches. Not much room for glass fusing but I get by for now.
The kiln is powered by two 600 watt side mounted elements. Twelve
hundred watts will get this puppy to 1850 degrees f in about 5 hours if
the wind isn't blowing. A little under powered but it works.
I can bisque fire ceramic molds in it.
This is an front view showing the fire brick and elements set in grooves in the side walls. Notice the wire pins to help hold the elements in place. They tend to move around after using the kiln for a while. The chains hold the door in the open position. The door is a welded steel box lined with brick and fiber, the three screws hold the brick in the steel shell. There are three on the bottom of the door you can't see,
The heart of the control system for this kiln is a Love
Controls 32A-020 digital controller. This type of controller will
accept any type of thermocouple input by selecting the proper type in the
setup program. Power for the control in the 020 option is anything
from 120vac to 240vac. You don't have to set a thing, just hook it
up. The 020 option specifies the controlling output voltage is 5vdc.
This is enough to power a solid-state relay used to turn the kiln on and
off. 
The
picture shows the controller mounted is a homemade box built out of aluminum
panels and wood sides. Just a little filing and hole drilling and
some paint and it was ready to go. About three evenings of work.
The gray cord in the picture plugs in the wall and the black cord and outlet
box are the output for the kiln. The thermocouple is the yellow wire
and connector resting on top of the box. The solid state relay is mounted
on the vertical panel at the back, This panel is 1/16 inch aluminum
and the relay is mounted with thermal heat sink compound to help get rid
of extra heat. Solid-state relays will die a fast death if they get
too hot. This relay is good for 25 amps and the kiln is only drawing
about 10 amps so there is some margin of safety. Heat sinks are a
subject in themselves and most suppliers have recommendations for the correct
size for each relay. Check out the details to be sure.
The next picture shows the details of the back of
the controller and how the wires exit. The plastic cover over the
relay keeps fingers out trouble.
The switches on the front panel control the main power
to the system and the power to the kiln. You can shut off the kiln
elements and open the door without shutting off the controller.
This
picture shows the inside view and how some of the wires run.
A close-up of the solid-state relay and how it's mounted.
The black and red wires are the power to the kiln. The green and
yellow wires are the control signal from the controller.
The schematic of the system. There is a fuse that
I installed in the line to the elements that does not show.
