Gordon on fri 18 jan 02
to fellow clayarters...... my boss and i were having a disagreement about
which is more acurate..
a junior cone in a kiln sitter or a computer run kiln......what are the
opinions of the group?
Paul Herman on fri 18 jan 02
Cones are better. They don't get their brains roasted from sitting too
close to the kiln. They like it hot.
Paul
----------
>From: Gordon
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: cone or computer
>Date: Fri, Jan 18, 2002, 3:36 PM
>
> to fellow clayarters...... my boss and i were having a disagreement about
> which is more acurate..
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
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melpots@pclink.com.
>
Snail Scott on sat 19 jan 02
on 1/18/02 6:36 PM, Gordon at emgordon@BATNET.COM wrote:
> a junior cone in a kiln sitter or a computer run kiln...?
A sitter cone will measure heat work, while a
thermocouple will only measure temperature. A
sitter is more likely to be miscalibrated, but
neither is immune to calibration errors, which
will increase with time if not checked.
A witness cone is the best 'reality check'.
-Snail
vince pitelka on sat 19 jan 02
> to fellow clayarters...... my boss and i were having a disagreement about
> which is more acurate..
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
Gordon -
A kiln run by a computerized controller relies on a thermocouple, which
responds only to temperature. A cone responds to temperature and duration,
just as do the clay and glazes. Any computerized controller working off a
thermocouple can never be as accurate as a cone. This doesn't mean that the
computerized kiln cannot be just as reliable (and certainly a lot less
bother) once one learns to use a specific kiln, but technically the cone is
always more accurate.
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/
Jim Tabor on sat 19 jan 02
My test kiln fires with cone 1 (2154) in the sitter with new parts and to get the
same results I have the large kiln program set to max at 2050. The metals in the
thermocouple and circuitry change over time. To me, it looks like the computer is
off by 104 degrees. I started using electronic controllers ( about 1980) before
they were featured on studio kilns and don't think they are any more accurate than
an analog pyrometer for reading temp. Time also takes it toll on kiln sitters. In
addition to the adjustment, the actuating rod gets thinner and bends to a point
that they are not very accurate.
In a disagreement, when you know you are right, the argument is over. Of course
your boss is right. He is your boss;-)
Anyway, depending on the condition of each device, either could be more accurate.
If both were new, I would go by the cone.
jt
Gordon wrote:
> to fellow clayarters...... my boss and i were having a disagreement about
> which is more acurate..
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Gary Ferguson on sat 19 jan 02
Gordon:
Depends on what you mean by more accurate.
A computer run kiln can be controlled to heat (or cool) to certain
temperatures over specified timeframes fairly precisely. This cannot be
done using just a kiln sitter and using low-med-high dial settings.
On the other hand if you want to measure actual "heat-work" which is how
clay and glazes respond and are really affected then the cone is more
accurate. It will mature (bend) when it has be at a temperature long enough
to "melt", regardless of what a computer setting dictates.
So basically a computer is excellent at controlling temperature but a cone
excels at determining maturity. This is why when I do Raku, I use a
pyrometer ("computer") to help monitor/control temperature, but then
visually check glaze melt ("cone") to determine when to remove the piece
from the kiln.
Gary Ferguson
www.garyrferguson.com
----- Original Message -----
From: "Gordon"
To:
Sent: Friday, January 18, 2002 4:36 PM
Subject: cone or computer
> to fellow clayarters...... my boss and i were having a disagreement about
> which is more acurate..
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
>
>
John Hesselberth on sat 19 jan 02
on 1/18/02 6:36 PM, Gordon at emgordon@BATNET.COM wrote:
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
Hi Gordon,
I don't agree with a couple of the answers you have been given, so I'll hav=
e
to add my two cents worth. A junior cone in a kiln sitter is subject to al=
l
kinds of drift and inaccuracy caused by gradual shifting of the kiln sitter
calibration, exact placement of the cones on the bar, particles of stray
clay or glaze interfering with the mechanism, etc. Computer programs are
far more sophisticated than just managing the temperature; there are
algorithms built in to simulate the behavior of the cones. They are, of
course, subject to thermocouple drift. On balance I'd say there is a sligh=
t
edge to the computer which is also (per info supplied by Stephen Lewicki of
L&L in a message a few days ago) significantly less likely to fail and
result in overfiring.
Of course the best of all is large cones placed in several places in the
kiln. I would not trust my pots to either of your two options. I have larg=
e
cones in every single glaze firing--the computer is usually allowed to be i=
n
charge of bisque firings. The Kiln Sitter's=AE role is one of safety
backup--period.=20
Regards,
John
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.co=
m
Email: john@frogpondpottery.com
"Art is not a handicraft, it is the transmission of feeling the artist has
experienced." Leo Tolstoy, 1898
Steve Mills on sun 20 jan 02
Cones measure heatwork, which is what melts glazes etc. computers take
the ache out of firing. At home and at work I/We have our kilns run by
automatic controllers, but the final shut off is by a Kiln Sitter,
thereby making the best of both worlds.
Whatever kit is used it MUST be properly serviced and maintained or all
advantage is lost.
Steve
Bath
UK
In message , Gordon writes
>to fellow clayarters...... my boss and i were having a disagreement about
>which is more acurate..
>a junior cone in a kiln sitter or a computer run kiln......what are the
>opinions of the group?
--
Steve Mills
Bath
UK
iandol on mon 21 jan 02
This is really a no issue argument.
Cones and information derived from a Pyrometer are based on separate =
concepts so they can never be directly comparable.
To get anything like a close comparison the junction of the thermocouple =
has to be inserted into the material of the cone to take the temperature =
reading. When I was working with the Chevenard Dilatometer and metal =
test pieces the thermocouple junction was split and forged into the =
test piece to get a complete circuit. This gave me an averaged =
temperature reading across sixty millimetres. There was always a =
discrepancy between this and the thermocouple which recorded my rate of =
temperature increase and decrease in the muffle furnace where the test =
piece was place.
If I had an exact match between the cone temp value and the thermocouple =
value I would be looking for causes. Obtaining precise reproducible =
temperature readings with the types of pyrometers which potters use, =
even with digital readouts needs special precautions and a special set =
up, like air aspiration.
Best regards,
Ivor Lewis.
Stephen J Lewicki on mon 21 jan 02
To all -
I would like to add one small opinion. I think the best system for
repeatability and accuracy is to use a three zone computer control and use
witness cones in each section and in each firing. Use the cones to
calibrate the control on a continual basis. Our DynaTrol control (and most
if not all others) have thermocouple offsets to adjust for drift and
varying kiln conditions and also cone offsets which allow you to match the
control to the witness cone performance when using the Easy-Fire cone type
programs.
Stephen J Lewicki
President
L&L Kiln Mfg., Inc.
877-513-7869
steve@hotkilns.com
Paul Taylor on mon 21 jan 02
Dear Gordon
Up to a few years ago I would have said the cone.
Now the computer has it . You can set it to turn the kiln on when you want
you can set rate in the rise in temp (The heat work) and record it JUST as a
cone does. you can set a soak rate - in a good kiln the atmosphere . You
can set the fall rate of the kiln and record it - a cone can not do that .
I wish it was not so. and I bet that the majority wish it as well because
cones come out as a few cents each and computers cost the earth. The only
thing a cone can do is be positioned any ware to make a record of kiln temp
difference.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
Alchemy is the proof that economics is not a science.
> From: Gordon
> Reply-To: Ceramic Arts Discussion List
> Date: Fri, 18 Jan 2002 15:36:29 -0800
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: cone or computer
>
> to fellow clayarters...... my boss and i were having a disagreement about
> which is more acurate..
> a junior cone in a kiln sitter or a computer run kiln......what are the
> opinions of the group?
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