Ann Semple on tue 5 mar 02
In my first firing of my new kiln, I discovered that the temperature displayed on the controller and the bending of the guard cones differed significantly . I suspect the only way to resolve this is to calibrate the sitter , and recalibrate as it ages.
I was going to set up a series of cone packs one behind the other on each level, and record the controller temperature when they bend. Is this a reasonable way to proceed or are there better ideas out there?
TIA for any advice.
Ann
annsemple@shaw.ca
Frederich, Tim on wed 6 mar 02
Ann,
The temperature that you saw may have been correct. The cones are measuring
heatwork so the temperature you see may change if the heating rate in the
kiln is not exactly the same as what you had programmed. Most electric
kilns tend to climb slower at the end of the firing as it reaches higher
temperatures. They will not match the rate in the program and so the end
point temperature will usually be lower than what you see posted on a cone
chart for a particular cone. This is the reason that it is important to use
witness cones to determine the true amount of heatwork taking place. Please
contact me if you have further questions about this.
I will be at NCECA next week either in the Clayart room or in the Orton
booth if any one has questions about cones or firing.
Best regards,
Tim
-----Original Message-----
From: Ann Semple [mailto:annsemple@SHAW.CA]
Sent: Tuesday, March 05, 2002 5:11 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: callibration of kiln sitter
In my first firing of my new kiln, I discovered that the temperature
displayed on the controller and the bending of the guard cones differed
significantly . I suspect the only way to resolve this is to calibrate the
sitter , and recalibrate as it ages.
I was going to set up a series of cone packs one behind the other on each
level, and record the controller temperature when they bend. Is this a
reasonable way to proceed or are there better ideas out there?
TIA for any advice.
Ann
annsemple@shaw.ca
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Steve Mills on wed 6 mar 02
Dear Ann,
The difficulty you are going to come up against is that Pyrometers (in
the controller) and cones measure 2 very different things: Controller
displays/Pyrometers measure the temperature in the kiln at the precise
moment you look at the display. Cones measure accumulated heat work over
the length of the firing up to the point when they bend. In that respect
they behave like the materials that go to make the pot/glaze, which is
why they remain firm favourites with an awful lot of Potters. What you
can do is set the finishing point way past the temperature that you
want, and fire watching the cones. When they bend, make a note of the
temperature reading, and set the controller to that point for that
programme for future firings. You will occasionally need to put a cone
into a firing to confirm that all is working as it should.
This is the technique we recommend to our customers when they buy a new
controller operated Kiln from us and want to confirm its *accuracy*.
Steve
Bath
UK
In message , Ann Semple writes
>In my first firing of my new kiln, I discovered that the temperature disp=
>layed on the controller and the bending of the guard cones differed signi=
>ficantly . I suspect the only way to resolve this is to calibrate the sit=
>ter , and recalibrate as it ages.
>I was going to set up a series of cone packs one behind the other on each=
> level, and record the controller temperature when they bend. Is this a r=
>easonable way to proceed or are there better ideas out there?
>TIA for any advice.
>Ann
>annsemple@shaw.ca
--
Steve Mills
Bath
UK
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