vince pitelka on tue 18 dec 01
First, you can get replacement Dawson parts from any ceramic supplier that
sells kilns, and that pretty much includes all of them.
There has been considerable mention of the problems with the cone support
prongs on the Dawson Kiln Sitter, and the possibility of cones sticking to
them and delaying the shutoff, with possibly serious results. First of all,
the cheapest replacement parts in your entire electric kiln are those cone
support prongs. They cost about two bucks per pair, and everyone with a
Dawson Kiln Sitter ought to have a half dozen pairs around, and at the first
sign of corrosion you should replace them. And as many people have pointed
out, it is also a good idea to periodically brush on a thin layer of shelf
wash. Definitely do not try to use anything else in place of the correct
cone support prongs.
There is another issues to consider here. Over time, dirt and debris will
accumulate within the porcelain tube that passes through the kiln wall, and
it will eventually intefer with proper movement of the sensing rod that
rests on top of the cone. Also, the sensing rod will eventually become bent
from its own weight, or from someone lifting up the catch on the outside of
the Sitter in order to shut the kiln off before the cone deforms (a very bad
practice). If that rod is slightly bent, then there is even more chance
that any debris in the porcelain tube can interfer with movement of the rod.
In either case, the rod may seem to move easily when cold, but can become
more resistant to movement when hot. It is a good idea to take a powerful
flashlight, lean down inside your kiln, and look into the end of the
porcelain tube. You will be able to see if there is any debris within the
tube, and whether the sensing rod is at all bent. If there is debris inside
the tube, DO NOT TRY TO BLOW IT OUT WITH COMPRESSED AIR, because you will
just impact it more firmly around the sensing rod. With a little care, you
can take a piece of thin stiff wire and bend a tiny "L" in the end of it,
and use that to rake out the debris. For best effect, remove the four
screws which mount the Kiln Sitter to the outside of the kiln, pull Kiln
Sitter away from the surface of the kiln, thus pulling the sensing tube out
of the hole in the kiln wall. You can then turn it with the tube facing
down and gently tap the tube, and all of the debris should fall out,
especially if you poke a wire in and out of the tube.
You can purchase a replacement sensing rod from Dawson, and it is not a
difficult replacement job. Be sure you get one of the appropriate length
rod, although they come oversize in several different lengths, and will have
to be trimmed to exact length with a hacksaw or heavy wire cutters. In
order to replace the sensing rod you will need to remove the porcelain
sensing tube from the kiln, and in doing so you will have the opportunity to
clean out any accumulated debris. Your kiln documentation should have
included a parts diagram for the Kiln Sitter, and that diagram will help
with the replacement. If you do not have that diagram you should ask for
one when you order the parts.
A common problem with the Kiln Sitter occurs when people loading or
unloading a kiln carelessly bump a shelf or a large pot against the cone
support prongs, possibly bending them and/or cracking or breaking the small
slots in the porcelain tube that hold the cone support prongs. If this
happens you need to replace the entire tube assembly. The part is a little
more expensive, but it is not difficult to do the replacement, as above.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
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