Custom Services on wed 27 sep 00
I need help. We are in the process of building another kiln. The plan was
to build a flat-top kiln, but one member of the team talked to two potters
who told her not to build a flat-top kiln. I have not heard any reasons not
to build one before. I like the concept and have heard good reports on
them. Now the project is bogged down with this doubt hanging over us. I
need data on the flat-top to get over this hump.
If you have experiences, both good and bad, with the flat-top design,
please email me. We are in the process of building this kiln now. Time is
critical. The slab was poured yesterday and the kiln shed is being built
right now.
The top will span an opening that is 63 x 54 inches. The walls are 9 inches
thick.
I am not concerned with the exit flue size debate, only the ability of the
flat-top to survive cone 10-11 firings in a gas kiln over a long time
period without failing. I would also like to hear the pros and cons of
firing characteristics. Any experience with excessive debris with these as
opposed to arches? We are using soft brick with the hard brick corner
bricks, as per Nils Lou' s book.
If Nils reads this, I respect your work tremendously. I would like to build
this kiln with a flat top and would welcome your input.
I will compile the responses for re-posting to the list after a couple of
days. If there is too much data to post, I will put up a small web page for
you to read the responses. (I pay for clay habits with web design work)
If you send posts with the word "flat-top" in it, I will build an email
filter to compile the posts.
Thanks in advance.
Pat Chesney
The Potter's House
Waco, Texas
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ARTISTINSC@AOL.COM on wed 27 sep 00
not the answer you are looking for but give that slab time to cure the
concrete. there is a need for it to cure to properly achieve its strength and
you do not want all that moisture in it that a little aging removes. i was
told a couple weeks would be recommended and a month would be the best. make
sure the concrete blocks underneath are aligned to vent under the kiln. what
are they using these days in place of transite on the concrete blocks between
them and the bricks?
Margaret
Ps. I built sprung arch myself, never did trust a flat top.
Tom Wirt/Betsy Price on thu 28 sep 00
Tonya...
First off, it is critically important, when the kiln is first built,
to check the snugness of the top frame after every firing. You should
have a torque wrench and be taking the bolts to 45 ft-lbs for the full
size kiln (don't know if this varies with smaller versions).
Think about what the bricks are doing up there during a firing. Quite
a bit of expansion on the hot face at temp, which then shrinks back
during cooling. This obviously slightly crushes the hot side of the
bricks and taking up the frame slack tightens this up. After a number
of firings, maybe 6, maybe 10, maybe 15, you'll find the bolts no
longer need snugging....things have settled in. Do not overtighten!
The fix you've tried, may or may not work long term. We did have to
rebuild a lid after maybe 100 firings, but that was mostly due to the
fact we used a 2" high temp brick. If you do find you have to
rebuild, be sure to look at Nils' latest plans if you don't already
have them. He recommends using 3" brick in a staggered pattern that
gives greater strength.
Tom Wirt
>Subject: Re: emergency flat-top kiln question
> I built a MFT last year. But I am having
> trouble with the top. I have had to put the original board back in,
give it
> a boost with a hydraulic jack, and retighten----twice. I think I am
going to
> have to take it loose in the spring and completely re-do the top.
Tjo62@AOL.COM on thu 28 sep 00
I built a MFT last year. I love the way it fires. I get cone 9 down and 10
bending pretty evenly top and bottom in about 11-12 hours. But I am having
trouble with the top. I have had to put the original board back in, give it
a boost with a hydraulic jack, and retighten----twice. I think I am going to
have to take it loose in the spring and completely re-do the top. Tonya
Johnson in Louisville, KY
Kurt Wild on thu 28 sep 00
>what
>are they using these days in place of transite on the concrete blocks between
>them and the bricks?
Expanded metal.
Kurt
email: KURT.L.WILD@uwrf.edu
website: http://wwwpp.uwrf.edu/~kw77
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