Dan Frazier on fri 3 mar 06
Hello!!
I'm building a chanell fire downdraft kiln. It is 5 feet wide outside wall
to outside wall. The walls are 11 1/2 inches thick 9 of which is solid
hardbrick. I'd like to build a sprung bonded arch with a rise of at least
a foot. The steel is in place already. The question is what shape of
skews can I use? Also, I only have regular straight hardbricks to use and
can't afford to buy archbrick. (I can buy a few skews tho).
Thanks!!!
Dan the Petaluma Potter
BJ Clark | Stinking Desert Ceramics on fri 3 mar 06
Dan,
Check your local library for "The Kiln Book" by Fred Olsen. It's got great =
a
great reference on what size skew's to use, #'s of bricks needed, etc.
--
BJ Clark
Stinking Desert Ceramics
bjclark@stinkingdesert.com
www.stinkingdesert.com
Marcia Selsor on fri 3 mar 06
I have always built kiln arches based on the interior size figured by
brick size. Then I refer to the old A.P. Green charts for
the rise per foot of span.
If yours is 5' wide minus 23" of wall thickness, You won't have full
brick sizes.
60 - 23=37 35" would be 5 fire bricks wide. Next, a foot rise on
a 3' span seems too much according to the book.
In the A.P. Green book, the greatest rise is 2" per foot. For a 3 '
span, the toal rise would be 6" and the inside radius
( for making your support form) would be 2' 6"for a 74 degree angle
and would require the following pattern combination of 9 inch thick
bricks 7 #3 wedge ( 9 x 4.5 x 3-2) 10 #2 wedges ( 9 x 4.5 x 3-2 1/2)
total 17 per row.
with Brand 4160-F for the skew.
I usually build arches with 4.5" depth using 2 courses thick. I have
seen too much breaking of bricks when 9" deep arch bricks are used.
For a rise of 1.608"/ft. on a 3" span for a total rise of 4 13/16"
inside radius would be 3' for a 60 degree angle, you would need: 13
#1 arch bricks 4
straight bricks and a Brand 4160 A for a skew. I also use car
engine valve springs on threaded rods rather than a rigid welded
frame to allow for
movement during the firing. Also the arch can be tightened when needed.
If you can't afford to buy arch bricks, try making a cast arch. We
did this at school many years ago for a soda kiln. Worked great!
Try to find a brick handbook from a brick manufacturer. A.P. Green
doesn't exist anymore to supply these books.
Good luck,
Marcia Selsor in Montana
On Mar 3, 2006, at 1:11 PM, Dan Frazier wrote:
> Hello!!
> I'm building a chanell fire downdraft kiln. It is 5 feet wide
> outside wall
> to outside wall. The walls are 11 1/2 inches thick 9 of which is solid
> hardbrick. I'd like to build a sprung bonded arch with a rise of
> at least
> a foot. The steel is in place already. The question is what shape of
> skews can I use? Also, I only have regular straight hardbricks to
> use and
> can't afford to buy archbrick. (I can buy a few skews tho).
>
> Thanks!!!
>
> Dan the Petaluma Potter
>
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