Sentry 2.0
Digital Temperature Controller
Complete Operating Instructions
Cone-Fire (pg 8-11)
From IdLE, press 1.
Available only on ceramic kilns. Fires to a pyrometric cone. Enter cone, speed, pre-heat, hold, and slow cool.
See pages 28-29 for instructions on upgrading your DTC 100, 600, 800 or 1000 series board to the Sentry.
Delay (pg 6)
From IdLE, press 3.
Enter time in hours:minutes.
Delays the start of firing.
Ramp-Hold (pg 12-15)
From IdLE, press 4.
Select stored program (1 - 4). Enter rate, temperature, and hold for each segment.
Alarm (pg 6)
From IdLE or during firing, press 7.
Enter a temperature. When alarm sounds during firing, press Enter.
Enter/Start (pg 7)
Press Enter/Start after each step in programming a firing. Press Enter/Start once to begin the firing.
Add Time (pg 6)
During firing, press 2.
Each additional key press adds five minutes to a hold. It works in both Ramp-Hold and Cone-Fire.
Present Status (pg 6)
Press 5 during firing.
Shows the segment that is currently firing. Works in both Ramp-Hold and Cone-Fire.
Program Review (pg 6)
From IdLE or during firing, press 6.
Shows the program that is loaded in memory and ready to fire, or the one that is firing.
Options (pg 17 - 21)
From IdLE, press 0. Press Enter for option displayed. Cone-Fire Options
SPd Speed Change the speed of a Cone-Fire program beyond the Fast, Medium, or Slow.
OFST Cone Offset Adjust controller to a witness cone.
FAN Vent Fan Selects when the vent fan will operate. (Special option not on all kilns.)
Standard Options
TCOS Thermocouple Offset
Calibrate the thermocouple temperature.
CHG- Select °F or °C.
TC Thermocouple Type Select Type K, S or R.
AOP AOP Outlet Select vent fan or alarm. This is a special option not on all kilns.
Id Computer ID Select identification number for output to a computer.
TEdE Temperature Deviation
Set temperature sensitivity of error codes.
SFTY Maximum temp.
ELEC Electronics Temp.
Check board for overheating.
LOCK Program Lock Make a program tamper-proof.
CFG Configuration Code
For technicians.
SOFT Software Version
For technicians.
TEST Element Test Diagnostics tool for checking elements.
RST Reset Removes cone and thermocouple offsets, etc.
Stop/Back (pg 7)
Press during firing or programming.
Stops a firing. In Options, takes you back to IdLE. During programming, takes you back one step each time key is pressed.
Multiple Zone Options
Cone Table & Skip Segment (pg 7)
From IdLE or during firing, press 9.
From IdLE, shows temperature for the cone you enter. While Firing: In Ramp-Hold, skips to the next ramp. In Cone-Fire, skips out of Pre-Heat or Hold.
DIFF Difference Largest temperature difference between any two zones.
CAdJ Center Adjustment
Change center heat of some two-zone kilns.
T123 Zone Temperatures Shows temperature of each zone.
1
Introduction
Thank you for purchasing the Sentry micro processor, our most advanced generation of digital temperature controllers. The easiest way to learn to operate the Sentry is to sit down in front of it with these instructions and play with it. Spend time understanding the controller before you begin to use it.
Damage caused by failure to follow instructions is not covered by warranty.
The Sentry operates in Cone-Fire and Ramp-Hold similar to the earlier DTC 600, 800, and 1000 series. If you are familiar with the earlier controllers, you can follow many of the same operating procedures with the Sentry.
The Cone-Fire mode applies to ceramics only. If you purchased a heat treating, glass fusing, enameling or jewelry furnace, your version of the Sentry will include only the Ramp-Hold mode, not the Cone-Fire. In this case, please disregard “FAST,” “MEDIUM,” “SLOW,” “Cone Fire” and “Cone #s” on your keypad.
If you purchased the TnF 2 portable controller, you should find a TnF 2 installation instruction sheet in addition to these instructions.
Instructions for multiple-zone kilns are included in this manual. If you are not sure whether your kiln is multiple-zone, look into the firing chamber. If you see two or three thermocouple tips, your kiln is multiple-zone. If you see only one thermocouple, skip multiple-zone instructions.
Do not worry if you hear a distinct clicking noise during operation. Mechanical relays click as they turn the heating elements on and off.
You can connect your Sentry controller to a personal computer, which will allow you to graph your firings and to monitor them from a distance. Ask for the computer inteface kit, which consists of a cable, a computer chip for the back of the Sentry, and software for your computer.
Once you learn the basic features of the Sentry, you will be able to control every stage of firing. This offers learning opportunities and convenience difficult to imagine with a manual controlled kiln.
©2001, by Paragon Industries, Inc. IM-204/5-01
2
Contents
Basic Pointers . . . . . . . . . . 4
Which Instructions
Apply to Your Controller . . . . . . . . . . 4 Room Temperature and Humidity. . . 4 Thunder Storms and Power Surges . 4 Display Lights . . . . . . . . . . . . . . . . . . 5 How to Get IdLE to Display . . . . . . . . 5 Firing Completion Message . . . . . . . 5 Repeat Firings . . . . . . . . . . . . . . . . . . 5 Thermocouple Inspection . . . . . . . . . 5 The “LId” Display. . . . . . . . . . . . . . . . 5
The Keys . . . . . . . . . . . . . . . 6
Correcting Entries . . . . . . . . . . . . . . . 6
1 / Cone Fire . . . . . . . . . . . . . . . . . . . 6
2 / Add Time . . . . . . . . . . . . . . . . . . . 6
3 / Delay. . . . . . . . . . . . . . . . . . . . . . . 6
4 / Ramp Hold . . . . . . . . . . . . . . . . . . 6
5 / Present Status . . . . . . . . . . . . . . . 6
6 / Program Review . . . . . . . . . . . . . . 6
7 / Alarm. . . . . . . . . . . . . . . . . . . . . . . 6
9 / Cone Numbers & Skip Segment . 7
Enter/Start . . . . . . . . . . . . . . . . . . . . . 7
The Options Key . . . . . . . . . . . . . . . . 7
The Stop/Back Key . . . . . . . . . . . . . . 7
Cone-Fire . . . . . . . . . . . . . . 8
Standard Schedules
Low Fire Cones 022 - 011. . . . . . . . 9 Middle Fire Cones 010 - 01 . . . . . . 9 High Fire Cones 1 - 10 . . . . . . . . . . 9 Speed (SPd) . . . . . . . . . . . . . . . . . . . 9 Pre-Heat (PRHT) . . . . . . . . . . . . . . . . 9 Hold (HOLd) . . . . . . . . . . . . . . . . . . 10 Cone-Fire Programming . . . . . . . . . 10 Slow Cooling (COOL) . . . . . . . . . . . 11 When the Kiln Shuts Off Too Soon . 11 For Kilns with AOP Outlet . . . . . . . . 11
Ramp-Hold . . . . . . . . . . . . 12
Definition of a Segment . . . . . . . . . . 12 Ramp-Hold Programming . . . . . . . . 13 User Programs (USER) . . . . . . . . . . 13 Firing a Stored User Program . . . . . 14 Rate . . . . . . . . . . . . . . . . . . . . . . . . . 14 Hold (HOLd) . . . . . . . . . . . . . . . . . . 14 AOP Fan. . . . . . . . . . . . . . . . . . . . . . 14 Segments for Controlled Cooling . . 14 Sample Firing Schedules . . . . . . . . 14
Cone-Fire Program Fired in Ramp-Hold . . . . . . . . . . . . . . . . . . 14
Sculptured Stoneware Bisque Firing Schedule, Cone 04. . . . . . . 14
Glass Fusing Firing Schedule . . . 15
Glass Slumping Firing Schedule . 15 Starting a Firing in a Hot Kiln. . . . . . 15 When the Kiln Shuts Off Too Soon . 15
Multiple Zone Kilns . . . . . 16
An Overview of Multiple
Zone Firing. . . . . . . . . . . . . . . . . . . . 16
Viewing Zone Temperatures . . . . . . 16
Two Zone Kilns: Adjust Heat in
Center Section (CAdJ). . . . . . . . . . . 16
Thermocouple Failure
In a Multiple Zone Kiln . . . . . . . . . . . 16
Power Output Lights . . . . . . . . . . . . 16
Testing Multiple Zone Elements . . . 16
Options: Cone-Fire. . . . . . 17
Cone-Fire Speed (Spd) . . . . . . . . . . 17 Cone Offset (OFST) . . . . . . . . . . . . . 17 Interpreting Cone Bending . . . . . . 18
When Cone Temperature
Is Off More Than 20°F/11°C . . . . . 18 Fan (FAN) . . . . . . . . . . . . . . . . . . . . 18
Options: General . . . . . . . 18
Thermocouple Offset (TCOS) . . . . . 18
Thermocouple Offset for
Ceramic Firings. . . . . . . . . . . . . . . 18
Calibrating Thermocouple Offset With a Digital Pyrometer. . . . . . . . 19
Setting Thermocouple Offset . . . . 19
Multiple Zone
Thermocouple Offset . . . . . . . . . . 19 Selecting °F or °C (CHG-) . . . . . . . . 19
°F/°C Temperature
Conversion Formula . . . . . . . . . . . 19 Thermocouple Type (TC) . . . . . . . . 19 AOP Outlet (AOP) . . . . . . . . . . . . . . 20 Computer ID (ID) . . . . . . . . . . . . . . . 20 Temperature Deviation (TEDE) . . . . 20 Maximum Temperature (SFTY) . . . . 20 Electronics Temperture (ELEC). . . . 20 Program Lock (LOCK) . . . . . . . . . . . 20 Configuration Code (CFG) . . . . . . . 21 Software Version (SOFT). . . . . . . . . 21 Element Test (TEST) . . . . . . . . . . . . 21 Reset (RST) . . . . . . . . . . . . . . . . . . . 21
Options: Multiple Zone . . 21
Zone Temperature
Difference (DIFF) . . . . . . . . . . . . . . . 21
Two Zone Kilns: Adjust Heat in
Center Section (CAdJ). . . . . . . . . . . 21
Zone Temperatures (T123) . . . . . . . 21
Error Messages . . . . . . . . 22
FTC / Failed to Cool. . . . . . . . . . . . . 22
FTH / Failed to Heat. . . . . . . . . . . . . 22
LTdE / Low Temperature
Deviation . . . . . . . . . . . . . . . . . . . . . 22
PF / Power Failure . . . . . . . . . . . . . . 22
BAdP / Bad Programming . . . . . . . . 22
ETH / Electronics Too Hot. . . . . . . . 22
FAIL / Thermocouple Failure . . . . . . 22
FTL / Firing Too Long . . . . . . . . . . . 22
HTdE / High Temperature
Deviation . . . . . . . . . . . . . . . . . . . . . 22
PF 2 / Power Failure . . . . . . . . . . . . 22
PF 3 / Power Failure . . . . . . . . . . . . 22
How the Sentry
Handles Power Failures. . . . . . . . . . 23
Using Ceramic Witness Cones
After an Extended Power Failure . 23
PLOG Error Codes. . . . . . . . . . . . . . 23
TCdE / Uneven Multiple
Zone Temperatures . . . . . . . . . . . . . 23
TCR / Thermocouple
Leads Reversed. . . . . . . . . . . . . . . . 23
Appendix A
Display Messages . . . . . . . . . . . . . . 24
Appendix B
Standard Cone-Fire Schedules. . . . 26
Appendix C
Upgrading the DTC 100, 600, 800 & 1000 to the Sentry . . . . . . . . . . . . . . 28
Appendix D
Orton Pyrometric Cone
Temperature Equivalents . . . . . . . . 30
Appendix E
Ramp-Hold Shorthand . . . . . . . . . . 31
Appendix F
Cone-Fire Shorthand . . . . . . . . . . . . 32
3
Safety
The warranty on your Sentry controller does not cover damage from overfiring, regardless of the circumstances. It is the operator’s responsibility to make sure the kiln turns off at the end of the firing. Follow these safety rules in addition to the ones in your kiln or furnace manual.
When the kiln is not in use, disconnect the power and keep the lid or door closed. (For larger kilns with heavy cordsets, we recommend a power disconnect box near the kiln.)
Do not leave the kiln unattended, especially near the expected shut-off time.
Wear firing safety glasses when looking into peephole of a hot kiln.
Do not touch hot sides of kiln or furnace. Keep unsupervised children away.
Install your kiln or furnace at least 12 inches from any wall or combustible surface. (See manufacturer’s recommendation for your model.)
Do not open lid or door until kiln or furnace has cooled and all switches are off.
Fire only in a well-ventilated, covered and protected area away from flammable materials. Keep cordset away from hot sides of kiln or furnace.
DANGEROUS VOLTAGE! Do not touch heating elements with anything. Disconnect kiln or furnace before servicing.
Do not operate if the controller itself is hotter than 150°F/66°C. (See instructions on page 20 for checking board temperature.) Never allow the firing room temperature to exceed 110°F/43°C. (Measure room temperature three feet from the kiln.)
Stop a firing by pressing the STOP button, not by disconnecting the power. In certain conditions, the controller will interpret a power interruption as a power failure and turn the kiln back on when you reconnect the power.
Chapter1
Basic Pointers
Which Instructions
Apply to Your Controller
The Sentry fires in two modes:
■Ceramic Cone-Fire, based on pyrometric cones.
■Ramp-Hold, based on custom firing rates and target temperatures.
Ceramic kilns use both Cone-Fire and Ramp-Hold. Heat treating, glass fusing, and enameling furnaces and kilns come with Ramp-Hold only.
1 From IdLE display, press 1. If CONE appears, you have Cone-Fire mode. If the 1key does not respond, you have Ramp-Hold mode only.
2 Press STOP to bring the controller back to IdLE .
Note: FAST, MEDIUM, SLOW, CONE-FIRE, and CONE #s printed on the controller faceplate apply only to Cone-Fire mode.
If you have Ramp-Hold only, skip pages 8 - 11.
Room Temperature and Humidity
It is okay to store the Sentry at sub-zero temperatures. But before operating, raise the room temperature to at least 32°F/0°C.
Note: The Sentry will register sub-zero °F/°C temperatures. However, 32°F/0°C is the lowest recommended operating temperature.
The circuit board is rated for 158°F/70°C maximum operating temperature. However, the maximum recommended temperature is 125°F/52°C. Open windows and exhaust hot air from the room to lower temperature. (See page 20 to check circuit board temperature.)
High humidity will not adversely affect the Sentry unless water condenses on the circuit board. In this case, do not fire the kiln until the moisture has evaporated from the board.
Thunder Storms and Power Surges
Unplug the kiln when not in use, especially during thunder storms and in areas with frequent power surges. If the kiln is part way through a firing when a storm begins, it may be okay to continue the firing. When the kiln shuts off, disconnect the power.
CAUTION: when firing the kiln during a storm, do not leave the kiln unattended!
4
Display Lights
Single Center Light: Time
A lower center dot appears during time display. It separates hours from minutes (i.e. 1 hour, 30 minutes displays as 01.30). During temperature display, the dot disappears.
Power Output Lights
The Sentry turns on the heating elements intermittently through relays. The power output lights in the right side of the display appear when the Sentry sends power to the relay(s).
■Single Zone Kiln When the Sentry sends power to the relays, all three lights appear.
■Two Zone Kiln The top light shows power to the relay for the top section of the kiln. The bottom light shows power to the bottom. Ignore the center light.
■Three Zone Kiln The top light indicates power to the top section relay, the middle light to the middle section, and the bottom light to the bottom.
°F 
°C
Single Right-Hand Light: °C
When temperature is displayed in °C, a light appears in the lower right. In °F it disappears.
How to Get IdLE to Display
The controller displays IdLE when you first apply power to the kiln. Operations begin from IdLE . You can’t fire the kiln until IdLE appears.
■If you press STOPduring a firing, AbRT will appear. To get back to IdLE , press ENTER.
■If the display shows an error message such as FAIL instead of IdLE , see pages 22 - 23.
■CPLT (firing completed) appears at the end of a firing. To make IdLE appear, press any key.
Firing Completion Message
When the firing has completed, four messages will cycle one after the other:
1CPLT (complete)
2Firing time in hours and minutes (amount shown does not include Cone-Fire slow cooling time)
3The temperature the kiln fired to in Cone-Fire, or the temperature of the last segment in Ramp-Hold
4The current kiln temperature
Note: If the alarm (see page 6) sounded, and then the kiln fired to completion, you will see ALAR instead of CPLT . Press ENTER. CPLT will appear.
Repeat Firings
To repeat the last firing, press ENTER from IdLE . The kiln will begin firing. This works in both Cone-Fire and Ramp-Hold. But first, make sure you are repeating the correct firing by using “Program Review” (see page 6). For repeat firings that you don’t want to inadvertently change, see “Program Lock,” page 20.
Thermocouple Inspection
The small rod protruding into the firing chamber is the temperature sensor, or thermocouple.
CAUTION: Bumping the thermocouple can push it out of the firing chamber. This could cause an overfire! The controller does not contain an alarm to detect this type of failure.
Thermocouples come in different widths. The wider the thermocouple, the farther it should extend into the firing chamber. A ¼” diameter thermocouple should extend into the firing chamber about 1”. A 1/8” thermocouple should extend into the chamber ½” - 5/8”.
Keep shelves, posts and ware 1” - 1 ½” away from the thermocouple. Keep an extra thermocouple on hand, especially if you fire hotter than 2000°F/1093°C.
If you are using a portable, separate controller, you will need to install the thermocouple onto the kiln. See the separate TnF 2 installation instructions.
The “LId” Display
Reasons LId appears in the display:
■The kiln is equipped with the optional safety switch. (The switch turns off power to the elements when the lid or door is open.) LId appears in the display while the lid is open during firing.
■On the back of the Sentry circuit board, at the top right
side, is a small two-pin terminal. If the connector on that terminal is missing, LId will appear in the display during firing. The elements will not turn on. (If the two-pin connector is missing, you can buy another from a computer supply store.)
■The safety lid switch is defective or the safety switch wire is broken.
5
Chapter2
The Keys
Correcting Entries
If you enter the wrong temperature, cone, time, etc., while programming, enter 0000. Then enter the correct numbers before pressing ENTER. See also the Stop/Back Key, page 7.
1 / Cone Fire
Cone-Fire is a method of firing ceramics
to a pyrometric cone. See Chapter 3, page 8, for details. To find out if your Sentry in-
cludes Cone-Fire:
1 From IdLE display, press 1. If CONE appears, you have Cone-Fire mode. If the 1 key does not respond, you have Ramp-Hold mode only.
2 Press STOP to bring the controller back to IdLE .
2 / Add Time
This key adds five minutes to a Hold. It is designed for ceramists who watch witness cones through the peephole, and for glass
artists who inspect the glass near the end of firing.
1During a firing, press Add Time. HOLd , and time in hold, will appear.
2Press Add Time again. The time shown will increase by 5 minutes. In a few seconds, temperature display will return.
Note: Add Time will add 5 minutes to Hold in either Cone-Fire or Ramp-Hold, even if no hold had been programmed. After hold time displays, 5 minutes are added with each press of the key.
3 / Delay
This delays the start of the firing by the amount of time entered. Use it to fit a firing into your schedule or to take advantage of
lower electric rates at night. Delay zeroes out after each firing. Therefore, it must be programmed for each firing.
1A Cone-Fire or Ramp-Hold program must be in active memory, ready to fire. (See pages 10 and 13.)
2From IdLE press 3. Enter delay time (i.e., 5 ½ hours = 05.30). Press ENTER.
3To begin Delay, press ENTER once from IdLE . A Delay count-down timer will appear.
Note: Press START during delay to end the delay and begin the firing. The maximum delay is 99 hours and 59 minutes.
CAUTION: For safety, do not leave the kiln alone during a delay or a firing. We cannot guarantee your kiln against overfiring even though the controller is
automatic. The operator assumes full responsibility for shutting the kiln off at the proper time.
4 / Ramp Hold
Ramp-Hold fires the kiln to the temperature you specify, whereas Cone-Fire fires to a pyrometric cone. Press 4 from IdLE to
program a firing or to select a stored program. See “Ramp-Hold,” page 12.
5 / Present Status
Press 5 during a firing to display the current segment that is firing. The messages that can appear in Present Status:
■RA 1 Ramp (see page 12), and segment number.
■Hd 1 Hold (see page 12), and segment number.
■PRHT Cone-Fire Pre-Heat (see page 9).
■COOL Cone-Fire Slow Cooling (see page 11). Uses for Present Status:
■You are firing a program that contains several heating and cooling segments. Without Present Status, it would be easy to lose track of which segment is firing.
■In Cone-Fire, you may think the kiln has fired too long when it is actually only in a slow cooling.
6 / Program Review
When you press ENTER to begin firing, 
the controller will fire the program that is in active memory. Program Review shows the
values for that program. The program in active memory is—
■The program that was fired last, or
■The program that was selected since the last firing.
Start Program Review from IdLE , or while firing, by pressing 6.
Note: In Program Review, Cone-Fire Fast speed displays as F 20 . Slow speed displays as S 20 . (These speeds are 20% faster and slower than the standard speed.)
7 / Alarm
The alarm sounds when the kiln reaches the alarm temperature you enter. Use the alarm to alert you to—
■Lower the lid from venting position (ceramics).
■Check the witness cone near shut-off time (ceramics).
■Check the fusing or slumping of glass.
■Remove the knife blade from the furnace at the end of heat treating.
You can enter only one alarm temperature at a time. However, after the alarm beeps, you can set the alarm for another temperature, as many times as you want, during the firing. You can enter a higher or lower temperature than the current temperature. Entering an alarm temperature automatically erases the previous alarm temperature.
6
Setting Alarm From Idle
1 From IdLE , press 7. ALAR will appear alternating with the last alarm temperature entered.
2 Enter alarm temperature. Press ENTER. IdLE will appear. (Enter 0000 to turn alarm off.)
Note: 9999, as an alarm temperature, automatically changes to the maximum temperature rating of your controller.
When the alarm sounds, shut it off by pressing any key except STOP. (The STOP key does not work while an alarm sounds.) If the alarm sounds as soon as firing begins, it is because the alarm was set to a temperature below the current temperature.
Setting Alarm During Firing
1The alarm beeps while the kiln is firing. Press 7.
2Enter the new temperature.
3Press ENTER. The kiln will continue firing.
If you touch 7, enter a new temperature, and forget to press ENTER, the controller will merely continue firing.
Note: When an alarm sounds, firing to completion does not shut the alarm off.
9 / Cone Numbers 
& Skip Segment
Cone Table
Look up a cone temperature with the 9 key.
1 From IdLE , press 9. CONE will appear, then the cone, if any, currently programmed in Cone-Fire.
2Enter a pyrometric cone number. Press ENTER. The display will show the cone temperature. If you enter a non-existent cone number, the display will show CONE , ready for you to enter a different cone number.
Note: Do not be concerned if the actual cone shut-off temperature does not match the Cone Table. The temperature of a cone varies with firing speed. The cone temperatures in Cone Table are for self-supporting cones fired at a rate of 108°F / 60°C per hour during the last hour of firing.
Skip Segment
Skip Segment works only during firing. It jumps from the current segment to the next one.
To skip a segment, press 9. SKIP will appear, then the current segment. Press ENTER. (If you change your mind and don’t want to skip that segment, don’t press ENTERafter SKIP appears. Instead, press 9 again. The firing will continue in the same segment.)
Skip Segment in Cone-Fire
In Cone-Fire, Skip Segment works in Pre-Heat and Hold: ■ To skip out of Pre-Heat and begin the cone firing.
■To skip out of Cone-Fire Hold. Slow Cooling will begin. (If the firing does not include Slow Cooling, Skip Segment will not end a Hold. Press STOPto end the firing.)
Skip Segment in Ramp-Hold
In Ramp-Hold, the firing will skip to the ramp of the next segment from either a ramp or hold of the current segment. (See page 12 for details on ramps, holds, and segments.)
Skip Segment Examples
For additional examples, see Chapter 4, pages 14 - 15.
Cone-Fire
■In Cone-Fire you are firing to an 05 witness cone for the first time. You select cone 04 with a 60 minute hold and a slow cooling. After 30 minutes in hold, the 05 witness cone bends to maturity. Use Skip Segment to end the hold and begin Slow Cooling.
Note: Once you know how much hold time will bend the witness cone, program that much hold for the next firing.
Ramp-Hold
■Skipping to a Cooling Segment: You have programmed 2167°F for a cone 5 glaze firing, followed by a segment for controlled cooling. Watching the witness cone through the peephole, you notice that cone 5 is bending at 2150°F. Use Skip Segment to end the firing segment and begin the one for slow cooling.
Note: Make a note of the temperature at which the cone bent. Program that temperature for the next firing.
■Skipping to a Hold: Skip Segment does not skip from a ramp to a hold. It skips to the next segment. If you need to skip to a hold, program an additional segment with the hold that you want. Then skip to that segment. Example:
Segment 1: rate 500°F to 1828
Segment 2: rate 200°F to 1750 with 30 minute hold
Enter/Start
■ Press ENTERafter each step in program-
ming a firing.
■ Press ENTER once to begin firing.
The Options Key
See Chapter 6, page 17.
The Stop/Back Key
You can stop a firing at any time (except when the alarm sounds) by pressing STOP.
If you inadvertently enter Ramp-Hold, Cone-Fire, or Options, you do not have to go through all the prompts to get back out. Press STOP to go to IdLE .
The STOP/BACK key is also like the Back button on an Internet browser. It works in Cone-Fire and Ramp-Hold programming. It will take you back one step every time you press the key.
7
Chapter3
Cone-Fire 
Cone-Fire mode is based on pyrometric cones. It is not designed for heat treating, glass fusing and enameling. For these firings, see “Ramp-Hold,” page 12. Use Ramp-Hold to fire ceramic pieces that require a custom firing schedule, such as some types of stoneware sculpture or crystalline glaze.
Pyrometric Witness Cones
The Sentry shuts off automatically without cones. Nevertheless, every ceramic firing should include at least one witness cone (also called the shelf cone). The witness cone is the most accurate measurement of heat work in a ceramic firing.
If you fire the same size load and type of ware regularly, the witness cones let you compare one firing to the next and alert you when something is wrong. For example, if the witness cone bends less and less with each consecutive firing, this may indicate thermocouple temperature drift.
Note: If the bending of the witness cone does not match the Cone-Fire shut-off, you may want to adjust Cone Offset or Thermocouple Offset. See pages 17 - 19. If the witness cones bend inconsistently from one firing to another, see “Sentry Troubleshooter,” a separate publication.
How to Position Cones on the Shelf
Position the witness cones so that you can see them through a peephole during firing. If the kiln takes longer than usual to fire, you may wonder if something has gone wrong and the kiln is overfiring. But by seeing the cones, you will know how the firing is progressing.
If you follow these guidelines, you should be able to see the cones even at cone 10:
■Place the cones 8” - 12” away from a peephole. Positioning them closer makes them difficult to see.
■Have enough space around the cones to keep them from touching a piece of ware when they bend.
■Position cones so that when viewed from the peephole, they are silhouetted by an element on the opposite kiln wall. (Keep cones at least 2” from an element.)
■The element that silhouettes the cones should be level with the lower part of the cone. If the element is in line with the upper part of the cone, you won’t be able to see the cone when it bends.
■If you use the three cone system, always have the higher temperature cone on the same side in every firing. Otherwise you can lose track of which cone is which.
■Wear firing safety glasses when viewing the cones through the peephole.
Silhouette the lower part of the cone against an element. Keep the cone 8” - 12” away from the peephole.
See your dealer if in
doubt about which cone number to use with each clay and glaze.
Firing Schedules
Cone-Fire uses three firing schedules:
■Low fire cones 022 - 011
■Medium fire cones 010 - 01
■High fire cones 1 - 10
Should you ever want to customize a Cone-Fire program, transfer the firing schedule to Ramp-Hold. See Appendix B, pages 26 - 27.
During a cone firing, press 5 (Present Status) to see which stage, or segment, of the firing the kiln has reached. The number displayed will be a segment number from one of these firing schedules.
Note: Pre-Heat shows in Present Status as PRHT . It is not given a separate segment number.
Firing time in each segment is approximate and depends on the age of elements, voltage, size of load, and the firing speed you have chosen.
CAUTION: Cone numbers beginning with 0 are lower in temperature than those without the 0. When programing a Cone-Fire, be sure you know the difference between an 05 and 5. See “Temperature Equivalents Chart for Orton Self-Supporting Pyrometric Cones,” Appendix D, page 30.
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Low Fire Cones 022 - 011
This range includes decals, over-decorations, lusters, and golds. The firing can be fast. Good venting is important, because oils and other organics burn off. Do not close the lid from the vented position until all odor has disappeared.
Low Fire Cones 022 - 011 Firing Schedule
Segment |
Rate Per Hour |
Time in Segment |
1 |
396°F/220°C |
2 hours |
|
|
|
2 |
108°F/60°C |
1 hour |
Firing time is about 3 to 5 hours, depending on the cone and speed.
Middle Fire Cones 010 - 01
Use this range for earthenware and commercial low-fire glazes. Glazes fired on bisque ware (ware that has already been fired) can be fired faster than the unfired greenware. In this cone range, slow firings can produce poor quality glazes.
In the following schedule, the firing is slowed during the silica phase change (1063°F/573°C).
Earthenware and clays that contain ball clays, talc, and kaolin will burn off water, carbon, and sulfur. This reduces weight by 10%.
Cooling too fast can produce glaze pinholes, blisters, and craters. Unless cooling is slowed near 1063°F/573°C, a physical change in the silica can cause the ware to crack. For this reason we recommend that you use Cone-Fire’s Slow Cooling option (see page 11).
We recommend a 10 - 20 minute hold when firing lead-free glazes.
Middle Fire Cones 010 - 01 Firing Schedule
Segment |
Rate Per Hour |
Time in Segment |
1 |
324°F/180°C |
2 hours, 30 minutes |
|
|
|
2 |
153°F/85°C |
35 minutes |
|
|
|
3 |
180°F/100°C |
2 hours, 40 minutes |
|
|
|
4 |
108°F/60°C |
1 hour, 30 minutes |
Firing time is about 6 to 8 hours, depending on the cone and speed.
High Fire Cones 1 - 10
This is the firing range for porcelain and stoneware. These bodies fire nearly to vitrification and can shrink up to 16%. Water, carbon and sulfur burn out during the early stages and must be vented. The amount of oxygen in the kiln affects the color of the fired clay. The high fire schedule below slows down during the last 210°F/100°C to produce better density in the ware.
Typical porcelain clays are formulated from kaolin, feldspars, silica and ball clays. Weight loss is 10 - 12% and shrinkage is as high as 20%. If overfired, porcelain may warp or blister. Cone-fire’s Hold option usually enhances porcelain.
High Fire Cones 1 - 10 Firing Schedule
Segment |
Rate Per Hour |
Time in Segment |
1 |
324°F/180°C |
2 hours, 30 minutes |
|
|
|
2 |
153°F/85°C |
35 minutes |
|
|
|
3 |
162°F/90°C |
4 hours, 35 minutes |
|
|
|
4 |
108°F/60°C |
2 hours |
Firing time is about 9 hours, 30 minutes to 11 hours, depending on the cone and speed.
Cone-Fire Features
Speed (SPd)
The Cone-Fire schedules shown on this page are standard. When you select Medium speed in a Cone-Fire program, the kiln uses these standard firing schedules. When you select Fast (1), the standard schedule fires 20% faster. On Slow (3), it fires 20% slower.
You can also alter the firing speed even more under Speed (Spd) in Options. See page 17.
Pre-Heat (PRHT)
Moist greenware can explode during firing. This happens when the moisture in the clay turns to steam rapidly and cannot escape fast enough. The Sentry Pre-Heat feature dries the ware at low temperature before the moisture can turn to steam.
Pre-Heat is sometimes necessary when firing thick greenware, such as stoneware. It may also be necessary in humid weather, which inhibits drying. If possible, however, avoid using Pre-Heat to dry greenware. If the greenware feels damp or cool when you touch it to your cheek, dry it longer before firing. Use a dehumidifier in humid weather. Drying greenware in the kiln tends to rust the kiln.
Note: During Pre-Heat, vent the lid. Otherwise the firebricks will absorb moisture, leading to rust behind the steel case. Moisture in the firebrick can also slow the firing to a crawl.
CAUTION: Venting the lid during Pre-Heat is so important that some ceramists use the extended vent position or even leave the lid open. If you do this, you must be near your kiln at the end of Pre-Heat to lower the lid.
Pre-Heat raises the temperature 60°F/33°C per hour to 200°F/93°C. Then it holds at 200°F/93°C for the time you specify. Pre-Heat works in Cone-Fire only. After Pre-Heat is finished, the kiln will automatically begin firing to the cone you have selected.
Note: At high altitude, water boils at a lower temperature. This may cause moisture in the ware to turn to steam even during Pre-Heat.
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Cone-Fire Programming
Use these instructions for your first firings. Later you may prefer “Cone-Fire Shorthand Programming,” page 32.
As the Sentry prompts for cone, speed, pre-heat, hold, and slow cooling, values entered for the last firing will appear. To use these values again, press ENTER.
To fire without Delay or Alarm: Follow steps 1 through 7 below. Then from IdLE press START. To use Delay or Alarm, see also page 6.
1 Apply power to the kiln. 8888 then IdLE will appear. (Press ENTER if IdLE does not appear.)
2Press 1. CONE will appear. Enter cone number. (If the 1 key does not respond, your controller uses Ramp-Hold only.)
3Press ENTER. SPd will appear. Enter speed: FAST (1), MEDIUM (2), SLOW (3). (Medium speed will display as Std .)
4Press ENTER. PRHT will appear. To use Pre-Heat, enter time. Otherwise enter 0.
5Press ENTER. HOLd will appear. To soak the ware at the end of firing, enter a hold time. Otherwise enter 0.
6Press ENTER. COOL will appear. To use Slow Cooling, enter cooling rate as degrees per hour. (180°F/82°C is maximum rate. Press 0 to turn Slow Cooling off.)
7Press ENTER. IdLE will appear.
8TosetAlarm: Press 7. ALAR will appear. Enter alarm temperature. (Press 0to turn alarm off.) Then press ENTER.
9To set Delay:Press 3. dELA will appear. Enter delay time. Press ENTER. (Delay zeroes out after each firing.)
10To start program, press ENTER once. STRT will appear, then temperature. If
Delay was programmed, DELA will appear, then time remaining until start. To stop the program during firing, press STOP.
When program fires to completion, CPLT will appear. Press ENTER. IdLE will appear. To shut off the alarm when it sounds during a firing, press ENTER.
Mirror Test
This test will help you determine how much Pre-Heat to use. Occasionally during Pre-Heat, hold a mirror near the top peephole. (Be careful to avoid burns.) The mirror must be at room temperature, not hot, so hold it near the peephole for only several seconds.
If the mirror fogs, moisture is still escaping from the
ware. When the mirror no longer fogs, you can exit Pre-Heat and begin the firing.
To interrupt Pre-Heat and begin firing to the cone in Cone-Fire, press 9(Skip Segment). SKIP , alternating with 1 , will appear. Press ENTER. Segment 1 of the firing will
now begin. (See Cone-Fire firing schedules, page 9.)
Note: If you are using a vent fan, such as the Orton KilnVent, turn the fan on during Pre-Heat. The fan will help to remove moisture. (AOP Fan users: see the Fan option, page 18.)
How to Use Pre-Heat When Kiln is Above 200°F/93°C at Beginning of Firing
If you begin firing with Pre-Heat in a kiln that is already hotter than Pre-Heat temperature, the kiln will skip Pre-Heat and begin firing to the cone. There are two ways to use Pre-Heat in this situation:
■Wait until the kiln cools below 200°F before starting the firing. This is the preferred method.
■Load the kiln and start the firing, but include enough time in Delay for the kiln to cool below 200°F before Pre-Heat begins.
Hold (HOLd)
Cone-Fire Hold heat-soaks the ware at the cone temperature at the end of the firing. Without Hold, the kiln shuts off after it reaches the cone temperature. Hold maintains the cone temperature for the period you specify. Hold helps even out the temperature throughout the kiln. It also helps the heat to penetrate completely into the clay. (Rapid firing is like cooking: the turkey will be done on the outside but not on the inside.) Hold helps glaze absorb china paint. It helps to heal glaze defects such as bubbles. A little hold time can yield dramatic results.
CAUTION: Too much hold time can overfire your ware and burn out colors.
One way to add Hold time without over-firing is to fire to one cone cooler than needed. Then add enough hold time to bend the next hotter cone. Hold time needed to bend the next cone will vary. As a rule of thumb, 45 - 60 minutes of hold = one cone of heat work.
Example: to fire to cone 05, program Cone-Fire for 06 and add 45-60 minutes of hold time.
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