Tracy Dotson on mon 2 feb 98
I think Ellen Bakers information is informative except for the last part
about " Properly sized, a strong outer wall can contain a "sprung" arch
without a metal superstructure or welded frame."
The thrust of a sprung always needs major support to keep it from spreading.
Maybe with massive walls you could get away with it but with a 9" wall you
do not want the skew block bricks to move at all. Some people like Cynthia
Bringle has over the years not put iron around her Catanary arch kilns but I
still do not know why she can get away with it. Good luck
Tracy Dotson........Penland NC
Bill Aycock on tue 3 feb 98
Tracy- she "gets away with it" because a catenary arch has the forces
balanced because of the nature of the curve. This is true WITHIN the curve
of the C arch- at the ends of the arch, there is a side force, but it is
small, if the proportions of the arch are right.
The small side forces of a well designed Catenary arch are taken out at the
floor, which is why no extra bracing is needed.
At 09:46 AM 2/2/98 EST, you wrote: *** in part ***
>----------------------------Original message----------------------------
> Some people like Cynthia
>Bringle has over the years not put iron around her Catanary arch kilns but I
>still do not know why she can get away with it. Good luck
>
>Tracy Dotson........Penland NC
>
>
Bill Aycock --- Persimmon Hill
Woodville, Alabama, US 35776
(in the N.E. corner of the State)
W4BSG -- Grid EM64vr
baycock@HiWAAY.net
Tracy Dotson on tue 3 feb 98
Bill you are correct in theory but over time the floor tends to continue to
spread in most cases because of heat expansion of the bricks. I still always
recommend stabilizing the floor brick to prevent this.
Tracy Dotson Penland NC
WardBurner@aol.com on wed 4 feb 98
Yea, I have to agree with Tracy. After awhile a catenary will tend to "walk
out" a little. Like Tracy mentioned, this is due to expansion at temperature (
a linear foot of wall will expand 1/16 of an inch at cone ten). Another factor
can be the low frequency vibration of "combustion rumble". This subtle shaking
can also make the base walk out a bit. One factor not mentioned is the
realitive roughness of the material the kiln is built upon. If it is rough
enough, this can help prevent "walk out". Cinder blocks are pretty rough while
polished concrete is not.
You can build one without base support (I have), but watch to make sure you
don't develope gaps in your floor bricks. This is a sign that the kiln is
spreading at the base. If this occurs, you can then add some support.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
Bill Aycock on wed 4 feb 98
Tracy- I'm sorry I was not clear- when I said "taken out at the floor" I
meant that that was where the bracing was needed. There IS a side force-
the old saying "TANSTAAFL" still holds. Tension, by pulling the base sides
together, or compression, by building bracing to the outside, for the sides
to push against, is still needed. I dont know which type Cindy uses.
At 01:45 PM 2/3/98 EST, you wrote:
>----------------------------Original message----------------------------
>Bill you are correct in theory but over time the floor tends to continue to
>spread in most cases because of heat expansion of the bricks. I still always
>recommend stabilizing the floor brick to prevent this.
>
>Tracy Dotson Penland NC
>
>
Bill Aycock --- Persimmon Hill
Woodville, Alabama, US 35776
(in the N.E. corner of the State)
W4BSG -- Grid EM64vr
baycock@HiWAAY.net
Tracy Dotson on thu 5 feb 98
Hay Bill....What does "TANSTAAFL" stand for?
This has been a pretty good discussion on arches. Most of the failures of
kilns I have found to be in the selection of materials (bricks) in the fire
boxes and flu area as well as the the Iron work not being strong enough to
hold things togather. I hope no one does what I did years ago.......Gaps
appeared in the floor so I filled them with sand. That cut down on the air
coming through the floor but after a number of fireings, the strapping blew
out with a bang. I figure that the sand just kept sifting down with each
fireing putting more presure on the iron until it gave way. Live and
learn.....There is no end to it.
Tracy Dotson....Penland NC
Bill Aycock on fri 6 feb 98
At 11:29 AM 2/5/98 EST, you wrote:
>----------------------------Original message----------------------------
>Hay Bill....What does "TANSTAAFL" stand for?
>
>Tracy Dotson....Penland NC
>
You KNOW I was hoping you would ask!
"There Aint No Such Thing As A Free Lunch"
(used frequently in the works of the science fiction master, Robert Heinlein)
Bill, Happy he has the snow excuse to stay in on Persimmon Hill
Bill Aycock --- Persimmon Hill
Woodville, Alabama, US 35776
(in the N.E. corner of the State)
W4BSG -- Grid EM64vr
baycock@HiWAAY.net
paul wilmoth on fri 6 feb 98
Hi Tracy,
Just a note about sand in the cracks! When I was in grad school I
was putting sand under large platters and sculptures to allow them to
shrink and move.
My professor told me it was a good idea but to make sure that I swept all
of it off the floor because it would expand when heated and widen the
cracks, pushing the floor apart.
best regards - Paul
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