KYancey on mon 18 mar 02
Recently, my new L&L J-230 kiln arrived with all the bells
and whistles. 3" brick, digital
controller, sure vent, power bottom, heavy duty elements,
and heavy duty thermocouples. I
cannibalized my old kiln bottom to use underneath my new
kiln's bottom, which was an excellent
idea, since I can reach underneath to touch the bottom of
the metal stand, and it is still cool to the
touch at cone 6.
My old Jen-Ken kiln was with me for over twenty years. I
thought that this new kiln would take
away all the interaction I had with my old kiln, but I was
wrong. In fact I feel I have better control and at the same
time, more free to leave for longer periods of time, only to
return when it is necessary to check witness cones as
opposed to having to be there to switch switches.
My interaction with my new kiln is to develop firing
programs and predict times when certain
temperatures need to be monitored. Using the forms
provided by the instruction manual, I
figured out how to calculate firing time of each programed
segment, and enter them into a
spreadsheet. This way I can also use the delay option and
"in theory" start a firing program while
away from the studio and have a pretty good idea when I need
to be around when peak
temperature is about to be reached. Here's what I did.
Step 1. Deduct the current kiln temperature from the goal
temperature. For the first segment this
would be room temperature, or a little hotter if your
loading soon after an unloading.
A= goal temperature
B= current kiln temperature
(A-B)=?
Step 2. Determine how the controller will raise the given
temperature, per minute, for the
particular segment by dividing your preferred rate of
temperature climb by 60.
C= preferred rate of temperature climb
60= minutes in an hour
(C/60)
Step 3. Take the difference in step1 and divide by the
quotient as determined in step 2.
(A-B)/(C/60)=minutes it takes to reach A
Step 4. Divide the minutes by 60 to determine the length in
time in hours.
(A-B)/(C/60)/60
Step 5. Adding soaking time should be done in tenths of an
hour, which is 6 minutes. So if you
want to add 1 hour and 20 minutes of soak time, enter that
as 1.3 That's close enough. Now the
formula is revised to look like this:
(A-B)/(C/60)/60+X= total time for segment.
X, being soak or pre-heat time.
This equation is applicable to each successive segment.
Also, if you are ramping down, you would enter a negative
number for the rate of decline.
Now it is wise to consider that this is only a way to
determine a general time, since kiln load, age
of elements and other factors play a role in kiln
performance, but it sure helps in getting to know your kiln.
I have devised a Lotus 123 spreadsheet with these formulas.
If anyone is interested, I would be
more than happy to share it. Just e-mail me Hope this
helps. Ken Yancey
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