Dave Finkelnburg on wed 4 dec 02
Hi all!
I'm busy and this has been beaten to death many times, so I'll keep my
whipping of this topic brief. :-)
EVERY electric kiln I have ever seen has a flat top. There are a lot
more flat top electric kilns firing pots than arched dome gas or other fuel
kilns. So what's my point? A flat top is not a dumb idea. It works.
At the same time, most electric kilns are relatively small. The width
of the kiln being spanned is not great, relative to the weight of the kiln
roof. So, the flat top design has some limitations. Springing a low arch
into a flat top design helps to combat that limit. Mel has posted before
how he does that, and it's in the archives. It's a very logical assist to
the flat top design.
A full blown sprung arch has design limits, too. In particular, some
restraint for the horizontal thrust is a requirement. That usually takes
some welding.
As a traditionalist, I like the look of a sprung arch, and built one
into my gas kiln. As a practical person I respect the fact that flat tops
are fast and easy to build, and they also work, within their limits. Rather
than arguing that one is better than the other, it might be more productive
to ask, what's causing a particular flat top to fail frequently. Are the
problems due to dimensions, method of construction, materials of
construction, manner of firing, or ???
Good potting,
Dave Finkelnburg in Idaho
vince pitelka on wed 4 dec 02
> As a traditionalist, I like the look of a sprung arch, and built one
> into my gas kiln. As a practical person I respect the fact that flat tops
> are fast and easy to build, and they also work, within their limits.
Rather
> than arguing that one is better than the other, it might be more
productive
> to ask, what's causing a particular flat top to fail frequently.
Dave -
Naaaaahhh, it's more productive to just admit that arches are better.
Seriously, I respect Nils Lou's innovative kiln designs and his firing
expertise, and there is little doubt that if someone follows his
construction plans and maintenance instructions for the Minnesota Flat-Top
to a "T," they will have a reliable, long-lasting kiln. But it still
remains a basic truth in the world of kiln aesthetics that flat-roof kilns
are UGLY, and additionally, they do not seem to offer the most streamlined
flame path. Arches are easy to construct, and when properly designed and
constructed they are completely maintenance free, with nothing that needs to
be tightened periodically. I say go with the low-maintenance design that
has been proven by several millennia of architectural use. If you don't
want to deal with a steel frame, then build a catenary arch kiln, where the
outward thrust of the arch is carried all the way down to the ground. A
sprung arch kiln gives more practical stacking space, and it is no problem
to find someone capable of welding the frame for you if you cannot do it
yourself.
Arches rule.
- 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://iweb.tntech.edu/wpitelka/
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