L&l/bartlett Controller Question

[Dick White]

An esoteric question for the cognoscenti - the Dynatrol/Barlett controller in L&L kilns prior to 2004 had the factory default thermocouple offset set to 50F, and is now set to 18F. Does anybody know why the change, but more to the point of my conundrum today, is there any good reason to leave it at 50 now? We are trying to tune an older kiln (using witness cones in all sections) and the TC offset needs some attention.

[S. Dean]

Dick,

 

Per the L&L website, the offset was changed due to a difference in the composition of the thermocouple protection tube.  See the  text highlighted in red below which came from

http://hotkilns.com/calibrating-kiln

 

HOW TO CHANGE THERMOCOUPLE OFFSET IN A DYNATROL: STEP BY STEP

• Turn kiln on with toggle switch. Wait 5 seconds.
• Press 1, wait 5 seconds. The kiln display will say STOP and then go into IdLE mode.
• Press OTHER about eight times until you see TCOS
• Press ENTER. See TC 1
• Press ENTER again
• It will flash between Â°FOS (which stands for Deg F Offset) and 0018 (The 0018 stands for a thermocouple offset of 18°F - which comes preprogrammed into the control to compensate for the ceramic protection tubes. By changing the offset to 0010 we are REDUCING the offset by 8°F- making it fire 8 deg hotter). (NOTE: On older kilns with a slightly different composition thermocouple protection tube the preprogrammed value is 0050).
• Press 0008 to reduce thermocouple offset by 10°F.
• Press 0013 to reduce thermocouple offset by 5°F.
• Press ENTER to accept your input.
• Do the same for all your thermocouples. The prompts will scroll past in the order of TC1, TC2 and TC3.

[Dick White]

Ah, thank you. I will have to look at the kiln and see if I can tell whether the tubes are original or have been replaced.

[oldlady]

so, when i need to change the thermocouple, i will get the new kind?  not sure of my kiln's birthday but i got it around then.

[neilestrick]

so, when i need to change the thermocouple, i will get the new kind?  not sure of my kiln's birthday but i got it around then.

 

When you change the thermocouple you do not need to change the protection tube.

 

Regardless of the original offset, you can change the offset to whatever you need it to be to give accurate firings.

[neilestrick]

 

Ah, thank you. I will have to look at the kiln and see if I can tell whether the tubes are original or have been replaced.

if you need to replace it, suggest you can check www.hkinventory.com for reference.

 

 

I suggest you buy directly from L&L or you'll have to do a lot of testing to figure out the correct offset.

[SunsetBay]

I have a brand-new L&L EasyFire kiln, and my test firing results were overfired by a full cone. When I went to adjust the thermocouple offset, I found that it was already set for 18 degrees. So if I want to add, say, 15 degrees, do I reset it to 33 degrees instead of 18? 

[Joseph Fireborn]

Sunset yes, your correct that's how I did mine.

[neilestrick]

I have a brand-new L&L EasyFire kiln, and my test firing results were overfired by a full cone. When I went to adjust the thermocouple offset, I found that it was already set for 18 degrees. So if I want to add, say, 15 degrees, do I reset it to 33 degrees instead of 18? 

 

That's interesting. I've never seen an L&L be off in the first test firing by more than 1/4 cone. Usually they're dead on. How close to the elements did you have the cones? Are your thermocouples touching the ends of the tubes inside? Check that the screws holding the tc's into the block are tight, and all the tc wire connections are tight.