Bill Arnold on sun 17 mar 02
It is quite easy to get a low rise arch using all wedges according to my old
A.P.Green manual. It simply depends on the choice of wedge angle and the
right scewblocks to anchor the ends of the arch.
----- Original Message -----
From: "vince pitelka"
To:
Sent: Sunday, March 17, 2002 8:36 PM
Subject: Re: NCECA Technical Session Notes
> > "Economical Refractory Shape and Composition for Kilns:" Jim Wunch, who
> > owns Larkin Furnace Construction Company of Conyers, Georgia, gave some
> > "kiln-building 101" basics and his no-nonsense opinions on which
materials
> > he liked for use in pottery kilns. He likes to mortar (very thinly) all
> > insulating fire brick in a kiln. He also likes to use a very short form
> for
> > supporting an arch while laying it. He pulls the form forward as the
arch
> > is laid up, and the form is then easy to remove when the job is
complete.
> > Wunch does not use straight brick, ever, in an arch. He discussed using
a
> > full half-circle arch, which he feels promotes more uniform temperature
> > inside a fuel-fired kiln.
>
> Dave -
> Jim Wunch is a hell of a nice guy, and gives great prices on refractory
> supplies, but I am not sure why he presented such a basic lecture. A lot
of
> people in the audience were very disappointed. I think Jim underestimated
> the level of knowledge in his audience.
>
> Also, his suggestions above are pretty basic and actually a little
strange.
> There is nothing technically wrong with a Roman arch (an arch which
> describes a half circle), but it does not make the kiln fire more evenly.
>
> The idea of NEVER using straights in an arch is very strange, especially
for
> someone selling refractories. If you do not use straights in the arch,
then
> you generally end up with a very high curve, or even a Roman arch. This
> requires a lot more arch brick, and they are normally more expensive than
> straights. I do not like to build arches with less than 2" of rise per
foot
> of span, or more than 2.5" of rise per foot of span, and for any normal
size
> studio kiln this usually requires some straight bricks. It is not a
problem
> at all, whether IFBs or hardbrick, as long as the straights are evenly
> spaced among the arch bricks.
>
> The only problem with using a shallow moveable arch form is that it makes
it
> harder to get a true locked arch. It is possible, but more difficult than
> with a complete arch form supporting the entire arch. You don't want to
cut
> any corners when building an arch.
>
> For the strongest arch (built on a full-size arch form), a row of bricks
is
> laid from front to back on each side of the arch, and the next course
> staggered one half brick, etc. This is continued all the way to the key
> bricks at the top, giving a much stronger monolithic locked arch with no
> joints lining up anywhere in the arch. A "ring" arch is where a single
> course of bricks is laid continuously from either side to the top, and
then
> another row is laid in front of that, etc. The joints line up all the way
> across the arch, and each "ring" is separate from the others. This gives
a
> weak arch that moves around a lot. There is no reason to build an arch
like
> this.
>
> Keep in mind that these are just my own opinions about brick arch
> construction, but they are based on lots of experience with and
observation
> of studio kilns.
> Best wishes -
> - 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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David Hendley on sun 17 mar 02
It works like this, Dave:
NCECA publishes a journal called 'the proceedings of the conference'.
It comes out usually almost a year after the conference.
Presenters are invited to submit an article for the journal. Not
everyone sends in a article, and of those that do, I don't know
if all are published.
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com
----- Original Message -----
From: "Dave Finkelnburg"
To:
Sent: Sunday, March 17, 2002 7:54 PM
Subject: Re: NCECA Technical Session Notes
> >These technical lectures. Will they be published? Somewhere?
> In the past there has been a book, which would come out many months
from
> the conference, which would include such information. Does anyone know if
> that will be done this year?
Dave Finkelnburg on sun 17 mar 02
Hi all!
Being a technical kind of person, I got all excited about the Technology
lectures Thursday afternoon in Kansas City. Here is a very, very brief
description of what I heard.
"Stable Glazes:" Ron Roy gave an excellent explanation of how he uses
software and a dilatometer to predict and measure glaze expansion. This is
great information in the light of recent reports on how glaze fit has such a
powerful effect on strength and resistance to cracking and chipping in fired
ware.
"Holistic Approach to Defect Reduction:" Despite the long title, Dr.
William Carty from Alfred University made this session fun, informative and
understandable. The gist of his talk was to say the majority of defects
which appear after firing, are really caused while making the ware. Dr.
Carty went on to clearly and concisely explain causes of common firing
problems -- warping and cracking, bloating and slumping. The most
fascinating part of his presentation, to me at least, was a short video
showing porcelain slumping between 990 and 1,100 degrees C, well below the
temperature at which the porcelain matures!
"Economical Refractory Shape and Composition for Kilns:" Jim Wunch, who
owns Larkin Furnace Construction Company of Conyers, Georgia, gave some
"kiln-building 101" basics and his no-nonsense opinions on which materials
he liked for use in pottery kilns. He likes to mortar (very thinly) all
insulating fire brick in a kiln. He also likes to use a very short form for
supporting an arch while laying it. He pulls the form forward as the arch
is laid up, and the form is then easy to remove when the job is complete.
Wunch does not use straight brick, ever, in an arch. He discussed using a
full half-circle arch, which he feels promotes more uniform temperature
inside a fuel-fired kiln.
"Sawdust Injection Burner:" Professor Lowell Baker at the University of
Alabama has been working on sawdust injection burners for years, and is
continuing to refine their design. For an excellent description of the
burner he referred listeners to Nils Lou's book, "The Art of Firing." A
current improvement includes a powered sawdust feed hopper that uses a
simple paddle-bladed "auger" to move sawdust out of a steep-sided hopper and
into the feed pipe. Baker is able to fire to cone 10 in as little as 3
hours with the sawdust burner and still get significant ash deposits on the
ware in the kiln.
These notes are far too brief to do justice to the presentations, but I hope
they give you some idea of what went on.
Dave Finkelnburg, safely back in snowy southern Idaho but with visions
of all kinds of ceramic art in Kansas City still swirling through his head
Craig Martell on sun 17 mar 02
Idaho Dave sez:
>He also likes to use a very short form for supporting an arch while laying
>it. He pulls the form forward as the arch
>is laid up, and the form is then easy to remove when the job is complete.
Hi Dave:
From the above description I'm assuming that this short form is used to
lay a ring arch, or in other words, and arch that isn't bonded by
staggering the joints in every course. I was thinking about the short form
though and came to the conclusion that it might be possible to lay a bonded
arch with a short form. The reason I'm mulling this over is due to my
preference for bonded arches. A ring arch will fail if you lose only one
brick while bonded arches will not fail if this happens. But, if Wunch
uses all arch brick and no straights and he mortars his arches they
probably wouldn't fail anyway.
regards, Craig Martell in Oregon
Ababi on sun 17 mar 02
These techinacal lectures.Will they be published? Somewhere?
Ababi
vince pitelka on sun 17 mar 02
> "Economical Refractory Shape and Composition for Kilns:" Jim Wunch, who
> owns Larkin Furnace Construction Company of Conyers, Georgia, gave some
> "kiln-building 101" basics and his no-nonsense opinions on which materials
> he liked for use in pottery kilns. He likes to mortar (very thinly) all
> insulating fire brick in a kiln. He also likes to use a very short form
for
> supporting an arch while laying it. He pulls the form forward as the arch
> is laid up, and the form is then easy to remove when the job is complete.
> Wunch does not use straight brick, ever, in an arch. He discussed using a
> full half-circle arch, which he feels promotes more uniform temperature
> inside a fuel-fired kiln.
Dave -
Jim Wunch is a hell of a nice guy, and gives great prices on refractory
supplies, but I am not sure why he presented such a basic lecture. A lot of
people in the audience were very disappointed. I think Jim underestimated
the level of knowledge in his audience.
Also, his suggestions above are pretty basic and actually a little strange.
There is nothing technically wrong with a Roman arch (an arch which
describes a half circle), but it does not make the kiln fire more evenly.
The idea of NEVER using straights in an arch is very strange, especially for
someone selling refractories. If you do not use straights in the arch, then
you generally end up with a very high curve, or even a Roman arch. This
requires a lot more arch brick, and they are normally more expensive than
straights. I do not like to build arches with less than 2" of rise per foot
of span, or more than 2.5" of rise per foot of span, and for any normal size
studio kiln this usually requires some straight bricks. It is not a problem
at all, whether IFBs or hardbrick, as long as the straights are evenly
spaced among the arch bricks.
The only problem with using a shallow moveable arch form is that it makes it
harder to get a true locked arch. It is possible, but more difficult than
with a complete arch form supporting the entire arch. You don't want to cut
any corners when building an arch.
For the strongest arch (built on a full-size arch form), a row of bricks is
laid from front to back on each side of the arch, and the next course
staggered one half brick, etc. This is continued all the way to the key
bricks at the top, giving a much stronger monolithic locked arch with no
joints lining up anywhere in the arch. A "ring" arch is where a single
course of bricks is laid continuously from either side to the top, and then
another row is laid in front of that, etc. The joints line up all the way
across the arch, and each "ring" is separate from the others. This gives a
weak arch that moves around a lot. There is no reason to build an arch like
this.
Keep in mind that these are just my own opinions about brick arch
construction, but they are based on lots of experience with and observation
of studio kilns.
Best wishes -
- 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/
Dave Finkelnburg on sun 17 mar 02
Ababi,
You asked,
>These technical lectures. Will they be published? Somewhere?
In the past there has been a book, which would come out many months from
the conference, which would include such information. Does anyone know if
that will be done this year?
Dr. Carty and Jim Wunch had handouts. When those were gone, more copies
were made and were at the NCECA booth in the exhibit hall. Perhaps those
are available from NCECA.
Dave Finkelnburg
vince pitelka on sun 17 mar 02
> From the above description I'm assuming that this short form is used to
> lay a ring arch, or in other words, and arch that isn't bonded by
> staggering the joints in every course. I was thinking about the short
form
> though and came to the conclusion that it might be possible to lay a
bonded
> arch with a short form. The reason I'm mulling this over is due to my
> preference for bonded arches. A ring arch will fail if you lose only one
> brick while bonded arches will not fail if this happens. But, if Wunch
> uses all arch brick and no straights and he mortars his arches they
> probably wouldn't fail anyway.
Craig -
The arch on our hoggama (groundhog/anagama hybrid) is about 16 feet front to
back, and it is a locked arch. As we laid the arch we just kept sliding the
archform forwards, and when the whole arch was done we did a little tapping
below and above with a hammer to get all the bricks perfectly even on the
inside surface. It worked out very well.
Best wishes -
- 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/
Brandon Phillips on mon 18 mar 02
I just built two sprung arch kilns these last two months and I used wedge
bricks for the arches. They taper the long way so you have a full 9" arch
without having to layer bricks. Our larger kiln is 45" wide (interior) and
using all #1 wedge bricks gave us I think about a 9" rise. No straights
needed. Just my two cents.
Brandon Phillips
>The idea of NEVER using straights in an arch is very strange, especially
>for
>someone selling refractories. If you do not use straights in the arch,
>then
>you generally end up with a very high curve, or even a Roman arch. This
>requires a lot more arch brick, and they are normally more expensive than
>straights. I do not like to build arches with less than 2" of rise per
>foot
>of span, or more than 2.5" of rise per foot of span, and for any normal
>size
>studio kiln this usually requires some straight bricks. It is not a
>problem
>at all, whether IFBs or hardbrick, as long as the straights are evenly
>spaced among the arch bricks.
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vince pitelka on wed 20 mar 02
> It is quite easy to get a low rise arch using all wedges according to my
old
> A.P.Green manual. It simply depends on the choice of wedge angle and the
> right scewblocks to anchor the ends of the arch.
Bill -
You are correct about wedges, but studio potters very rarely use wedge
bricks because it is so much more expensive to build a 9" arch from wedges
than to build a 4.5 inch arch from arch bricks. My first gas kiln had a
Roman arch built from wedges because I got them for free. Wedges are
available in more angle variations, whereas arch bricks are widely available
only in #1, #2 and #3. There is no compelling reason to use wedges on a
studio kiln.
Best wishes -
- 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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