shane mickey on sat 16 jun 12
hey all,
well john britt had pointed out me as a source. i finally jumped on and loo=
k=3D
ed at these responses.
same ol same ol. folks like to point out absolutes! i find that interesting=
.=3D
even noticed some oddities=3DC2=3DA0
as usual. IFB brick expansion is very minimal so expansion joints are gener=
a=3D
lly accepted as not being
needed in an all ifb kiln. Hard brick move like ticks in the night. I perso=
n=3D
ally build "loose" which means
about a 1/32 or 1/16th between brick. I also will use the difference betwee=
n=3D
interior hard and exterior
soft brick kilns. the hardbrick are generally shorter so i will leave gaps =
h=3D
idden in the corners.
now to answer johnathons question. floors! no one ever talks or addresses f=
l=3D
oors.
if your are doing alternating layers of hard and soft, the hard brick layer=
=3D
will be shorter so you can bury the
gap under the wall which allows the floor to expand. if not, just leave a s=
t=3D
rip under the wall anyway for expansion.
=3DC2=3DA0
OK. =3DC2=3DA0here is where i will upset some of the responders. metal will=
not =3D
expand in the same rate as the brick.
the metal gets warm, not super hot so its expansion is very minimal. also, =
i=3D
t is tightened down, or (hopefully not)
welded and thus cant expand. DO NOT LISTEN TO FOLKS SAYING THE METAL WILL E=
X=3D
PAND!
=3DC2=3DA0
here is why walls buckle in or out: it is all do to the metal. not expansio=
n=3D
joints. if you over tighten the metal
then the walls cant expand and hence the walls expand and like a strap of s=
t=3D
eel under pressure from the ends
it will bend. that is the main reason for walls buckling. springs?! never. =
h=3D
ow do you spring an arch securely if you
use springs? the tension is variable, bad idea.
I am using an almost (99%) full proof sprung arch these days. not giving ou=
t=3D
secrets as it is my=3DC2=3DA0
income to build kilns. before the hobbyist builders jump down my throat, pl=
e=3D
ase understand that i monitor=3DC2=3DA0
my kilns as they age, talk to clients past. I have a deep passion for the s=
c=3D
ience of kilns. not a relax and just
do it attitude. come on folks, we are talking about harnessing 2300 degrees=
!=3D
!! this is not a game!!!!
please be advised that when you give advice about this stuff you are messin=
g=3D
with someones safety.
Sure, kilns have been built for decades on a whim. that is fine. as marc wa=
r=3D
d has said, only take risks you=3DC2=3DA0
can afford to take. can you afford to waste thousands of dollars in materia=
l=3D
s? can you afford to blow up your
studio?=3DC2=3DA0
peace
shane mickey
=3DC2=3DA0
http://www.shanemickeypotterslife.blogspot.com/
James Freeman on tue 19 jun 12
On Sat, Jun 16, 2012 at 10:11 PM, shane mickey wrote=
:
springs?! never. how do you spring an arch securely if you
use springs? the tension is variable, bad idea.
I agree with Shane's comments regarding the use of springs in a kiln
frame. The Abernathy kiln at our local college was originally built with a
frame consisting of heavy angle iron uprights at the corners, held together
via threaded tie rods with automotive valve springs providing compression
at each juncture. When the kiln was firing, the valve springs did
precisely what they were supposed to do, and allowed the kiln frame to
expand freely as the kiln expanded. The problem with the valve spring
idea, though, is that when the kiln cooled, the springs could not possibly
provide enough compression to push the bricks back into place (if such were
even possible, which I doubt). Thus, the bricks just cooled in their new
pushed out position, to be pushed out even further with the next firing.
The door, plumb at one time, was 2" wider at the top than at the bottom,
and they had thick cables wrapped around the kiln in an attempt to hold it
together.
When I.B. Remsen and I moved and rebuilt the kiln, I welded the frame up
tight, with solid channel iron banding replacing the tie rods. We also
added metal to prevent the skew bricks from moving. This was about 8 or so
years ago, and the kiln is still straight and true after a couple hundred
firings. Not sure why our experience with a tight frame was different than
Shane's. Perhaps Fred's idea of the metal stretching is correct, or
perhaps the bricks just don't expand enough to cause themselves a problem
inside a tight frame. Note: The kiln is IFB, with a hard brick floor.
All the best.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
jonathan byler on tue 19 jun 12
IFB's don't move as much with heat, hence the tight frame, tight
construction working out for you.
On Jun 19, 2012, at 8:53 AM, James Freeman wrote:
> On Sat, Jun 16, 2012 at 10:11 PM, shane mickey
> wrote:
>
> springs?! never. how do you spring an arch securely if you
> use springs? the tension is variable, bad idea.
>
>
>
>
> I agree with Shane's comments regarding the use of springs in a kiln
> frame. The Abernathy kiln at our local college was originally built
> with a
> frame consisting of heavy angle iron uprights at the corners, held
> together
> via threaded tie rods with automotive valve springs providing
> compression
> at each juncture. When the kiln was firing, the valve springs did
> precisely what they were supposed to do, and allowed the kiln frame to
> expand freely as the kiln expanded. The problem with the valve spring
> idea, though, is that when the kiln cooled, the springs could not
> possibly
> provide enough compression to push the bricks back into place (if
> such were
> even possible, which I doubt). Thus, the bricks just cooled in
> their new
> pushed out position, to be pushed out even further with the next
> firing.
> The door, plumb at one time, was 2" wider at the top than at the
> bottom,
> and they had thick cables wrapped around the kiln in an attempt to
> hold it
> together.
>
> When I.B. Remsen and I moved and rebuilt the kiln, I welded the
> frame up
> tight, with solid channel iron banding replacing the tie rods. We
> also
> added metal to prevent the skew bricks from moving. This was about
> 8 or so
> years ago, and the kiln is still straight and true after a couple
> hundred
> firings. Not sure why our experience with a tight frame was
> different than
> Shane's. Perhaps Fred's idea of the metal stretching is correct, or
> perhaps the bricks just don't expand enough to cause themselves a
> problem
> inside a tight frame. Note: The kiln is IFB, with a hard brick
> floor.
>
> All the best.
>
> ...James
>
> James Freeman
>
> "Talk sense to a fool, and he calls you foolish."
> -Euripides
>
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/resources
shane mickey on wed 20 jun 12
James,
i when i spoke of not welding, it was for one specific reason. Tension on a=
=3D
sprung arch needs to be "sprung" which happens through compression of the a=
r=3D
ch once laid. If a Frame is welded first, then the arch laid, the only comp=
r=3D
ession happens when the last brick, the keystone, is forced into the arch. =
t=3D
his does some springing. I have found that forcing the keystone down then t=
i=3D
ghtening up on the irons just a little bit truly springs the arch upward. T=
h=3D
e kiln designed by I,B, is truly a wonderfully firing kiln. i remember the =
a=3D
rticle well! It has not walked or bulged for the reason you state, Its enti=
r=3D
ely IFB (minus the floor).
Happy firings!!!
shane
=3DC2=3DA0
http://www.shanemickeypotterslife.blogspot.com/
James Freeman on wed 20 jun 12
On Wed, Jun 20, 2012 at 9:01 AM, shane mickey wrote=
:
James,
i when i spoke of not welding, it was for one specific reason. Tension on a
sprung arch needs to be "sprung" which happens through compression of the
arch once laid. If a Frame is welded first, then the arch laid, the only
compression happens when the last brick, the keystone, is forced into the
arch. this does some springing. I have found that forcing the keystone down
then tightening up on the irons just a little bit truly springs the arch
upward. The kiln designed by I,B, is truly a wonderfully firing kiln. i
remember the article well! It has not walked or bulged for the reason you
state, Its entirely IFB (minus the floor).
Happy firings!!!
Shane...
I think we are kind of on the same page. I thought you were saying that
you did not weld up your frames tightly. As I read you now, I understand
(???) that you do weld up the frame tightly or cinch it up tightly with tie
rods or some such, but only after you set the arch. If I do understand you
correctly, I wonder how you are able to compress the sides of the arch
inward to "spring the arch upward", when it seems that to do so one would
have to at the same time compress in the walls of the kiln, which doesn't
seem possible. I guess I'm just not able to picture it. If this is a
trade secret, don't worry about it. My next kiln will be a flat top anyway=
!
I'm not sure I stated why I thought the kiln spread out, but here is my
hypothesis: When the top of the school's kiln expanded, which the valve
spring frame allowed, the arch sags and spreads. As the kiln cools, there
is no way a couple of valve springs can provide enough compression to
squeeze the walls back together and to push the arch back up to where it
was, so the sagged arch holds the walls apart. I do not believe any
compressive force could push the arch back up, because it seems like the
bricks would crush long before that happened. This is just a intuitive
guess, as I have no engineering data, nor do I possess the math skills to
construct the required equations, but I'm pretty sure it's correct.
Anyway, each time the kiln fired, it would repeat this sequence of
spreading and dropping until the point where the valve springs were fully
compressed, at which point the frame is essentially "fixed" rather than
expandable, which explains why the door was 2" wider at the top than at the
bottom.
The kiln we rebuilt actually predates IB's kiln by quite a few years. It
was built by JT Abernathy himself in Ann Arbor, about 30 or 40 years ago.
The college bought it used and moved it to campus about 20 or so years
ago. When the administration built the department a new kiln shed, IB and
I disassembled the kiln, then rebuilt it inside the new shed with a few
modifications. Funny story: The first time I met IB, he stuck out his
hand and said "IB Remsen". I shook his hand and blurted out "I be James".
Luckily, he has a sense of humor!
Take care.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Vince Pitelka on thu 21 jun 12
I acknowledge the expertise and experience of those who have written about
springing a sprung arch, but I do not see what the issue is. There is no
mystery to springing a tight sprung arch. You build the walls up first,
weld up a sturdy frame with appropriate buttressing members to support the
outward thrust of the arch, and then place the arch form on a temporary
support including removable wedges. With hard brick, you make sure you are
laying the brick up tight with no gaps using the right combination of skews=
,
arches and straights in the correct sequence, and then cast the key brick
with Mizzou or some other appropriate high-duty castable. With IFB you lay
the arch up tight with the right combination of skews, arches and straights
and then shave the key brick for a perfect fit. You tap out the wedges to
drop the arch form, and voila you have a correctly sprung arch that gives
very long service with no problem as long there a not other mitigating
factors like heavy and frequent atmospheric firings that will inevitably
cause the bricks to start shifting around.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Mike Gordon on fri 22 jun 12
All you have to do is look at any sprung arch kiln built by A.D.
Alpine, examine the frame take measurements & ask people who have had &
fired them for years. Ask them how long they have had them. Schools,
art centers,ect. Mike Gordon
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