The Cone-Fire mode in the Sentry digital controller is used for firing ceramics to a pyrometric cone. Cone-Fire is available in the Sentry controller used on Paragon ceramic kilns. Cone-Fire is not available on glass kilns.
To estimate the length of a firing in Cone-Fire mode, you will first need the Sentry instruction manual. If you do not have a copy, you can download it at no charge from the Manuals section of this website.
The firing schedules programmed into Cone-Fire are shown on pages 26-27 of the manual. These schedules are used in Medium Speed.
You will find a rate and temperature for each segment of a firing schedule. To estimate total firing time, first subtract room temperature from segment 1 temperature. Then divide by its rate. That will give you the firing time for segment 1.
To figure firing time for the other segments, subtract the temperature of the preceding segment from the segment you are figuring. Then divide by rate.
Example Firing schedule for cone 06, degrees F.: Segment 1: 324 rate, fired to 1022 Segment 2: 153 rate, fired to 1112 Segment 3: 180 rate, fired to 1720 Segment 4: 108 rate, fired to 1828
Figuring firing time:
Segment 1: 1022 minus room temperature (80) = 942 divided by 324 = 2.9 hours Segment 2: 1112 minus 1022 = 90 divided by 153 = .58 hour Segment 3: 1720 minus 1112 = 608 divided by 180 = 3.37 hours Segment 4: 1828 minus 1720 = 108 divided by 108 = 1 hour
2.9 + .58 + 3.37 + 1 = 7.85 hours total firing time, Medium Speed
Subtract 20% for Fast Speed. Add 20% for Slow Speed.
Fast Speed: 7.85 – 20% = 6.28 Slow speed: 7.85 + 20% = 9.42
Figuring the firing time of a Cone-Fire schedule will give you a good understanding of Ramp-Hold mode. Each Ramp-Hold segment has a rate, temperature, and sometimes hold. Once you understand this, you can change a Cone-Fire schedule to suit your needs and enter it into Ramp-Hold.