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Kilns, Cone, And Tuning


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Hi all,

 

I'm trying to tune my new L & L E23 kiln. I did the burn in and test fire with two cone 5 cones in the load of just furniture. It ran a little hot. I only had the two cones that were supplied with the kiln. One of the cones touched the shelf and the other started to lay down beyond touching the shelf. I'm assuming at this point I was at cone 5.5 or 6. I adjusted the thermocouple 5 degrees more so the kiln would run a bit cooler. I ran a bisc load, with four cone 05 cones, I don't have the 04 and 06 cones yet, and the tips just touched the shelf. My questions at this point are, how will effect a cone 6 firing? Should I think about adjusting the offset on the TC another 5 degrees or should I fire it at cone 5 to get to cone 6 knowing it will run a little hot? This firing will have a full cone pack. There are important pots in this next load and I would hate to over fire them. Am i being too anal about this? Is there really a big temp difference from a normal cone droop and touching the shelf?

 

Thanks in advance!

 

 

 

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Consistency is generally the most important aspect of electric firings. People on this forum can and will go into the more minute details about firing and cooling. The peak temperature, hold times or cone reached, and cooling rate have significant influences on glaze results. Most of us have found what we like and continue to do it again and again.

 

When I opened my studio and got a kiln and glaze etc etc I fired the first glaze load full -- and generally had bad results because I wasn't familiar with this particular kiln/clay/bucket/etc.

 

So I would have to say: take the 2 days and little bit of electricity to fire some smaller glazed test pieces before finishing work you really care about in your new kiln. Hold off on firing the real pieces until you like the results enough.

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  • 1 month later...

Hello!  I'm new here and would love some suggestions.

 

My LL e28s has been underfiring at ^04 and overfiring at 6, (according to witness cones), and I've tried changing the thermocouple offset, and then the cone offsets, as recommended by the manufacturer, instead of firing a cone higher or lower.    Just when I thought I had it worked out, the last firing I did (with a cone offset of 75 degrees cooler), fired to cone 7.  It had gone to cone 6 at 65 degrees cooler.  Right now I'm running a glaze load to cone 5, with a 10 minute hold, and hoping it turns out somewhere between 5 and 6.    Anyone out there have the same model kiln?  I'm wondering how you set up your shelves as well.

Thanks in advance. 

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Hello!  I'm new here and would love some suggestions.

 

My LL e28s has been underfiring at ^04 and overfiring at 6, (according to witness cones), and I've tried changing the thermocouple offset, and then the cone offsets, as recommended by the manufacturer, instead of firing a cone higher or lower.    Just when I thought I had it worked out, the last firing I did (with a cone offset of 75 degrees cooler), fired to cone 7.  It had gone to cone 6 at 65 degrees cooler.  Right now I'm running a glaze load to cone 5, with a 10 minute hold, and hoping it turns out somewhere between 5 and 6.    Anyone out there have the same model kiln?  I'm wondering how you set up your shelves as well.

Thanks in advance. 

 

65-75 degrees is a huge offset. You shouldn't need to make adjustments anywhere near that big. I would set it back to the factory settings and go from there. It should not be that far off. Also double check the condition of your thermocouples. Are the thermocouples back to the factory settings? If you've got thermocouple and cone offsets changed, you may just have everything too out of whack for it to function normally. 

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I agree that it's very strange to have such a big offset.  I started off with factory settings and was told to adjust them 10-25 degrees because it was consistently firing to cone 7 when set to 6, but that didn't help.  I did thermocouple first, then cone offsets.  Separately.  The thermocouple offsets have been back at factory settings for a while now.  I just fired a load at cone 5 factory settings -  unfortunately I only had cone 7 witness cones, but they barely bent so I figure I'm pretty close now.  I didn't have glaze melt down either like I did last time.   I'll run another another glaze load in a week or so and I have witness cones at last so I'll get a better picture about what's really happening in there.

My kiln is pretty new.  I've only fired it 20 times. If there was a problem with the thermocouples what would that look like?

Thanks for your help!

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Hi, 

I also have an LL e28S and just finished my first bisque to ^04 and it over fired by a lot, the 3 cones 05, 04 and 03 were all the way down. The previous firing was the empty kiln, just furniture, and it also over fired by 100F. The empty one I was firing to cone 5 (2167F) and at 2063F the cones were touching down so I stopped it.

This time I was firing with a loaded kiln, a little loose, to ^04 (1945F) and unfortunately i couldn't see the cones well while firing but when unloading both packs were all the way down. I should have fired to 1940F but 5 degrees can't explain this. The last segment of the firing was at a rate of 108F/hour .

I had the vent-sure vent going the whole time, even when trying to check on the cones. Then I read this on the vent manual, and now I'm confused, one is not supposed to check the cones??

IMPORTANT CAUTION DO NOT OPEN ONE OF YOUR PEEPHOLES WHEN USING A THE VENT-SURE VENT (regardless of what it may say in the Dawson Kiln Sitter manual). Opening a peephole is acceptable ONLY when venting your kiln manually by opening the lid. Also do not open the lid when venting with the Vent-Sure. It will let in far too much air when you are using a motorized vent. THIS CAN BE DANGEROUS because the cold air can cool down the thermocouples or Dawson tube assembly and trick the thermocouple or cone into thinking that the kiln is much cooler than it really is. THIS COULD LEAD TO AN OVERFIRED KILN OR OVERFIRED WORK!

Not sure how to fix this. Thanks!

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I think it means keeping it open, not just opening it for a few seconds to check the cones.

 

Where were your cones? Too close to the elements can cause them to read inaccurately.

 

Make sure your thermocouples are touching the ends of the protection tubes. If they're not they'll read low and the kiln will overfire. 

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I was thinking that that's probably what they meant, but wasn't sure :)

I'll check where the thermocouples are, should I just push them? not sure how to check that , sorry.

The cones were ~2 inches from the edge of the shelf, one shelf closer than the other to the elements

Thanks!

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Hi RBS,   I also run the vent-sure the whole time, but I don't check the cones while the kiln is on, I look at  them after the load has cooled.  You are wearing the protective glasses when you peep in right?   I put my cones on the side away from the thermocouples - not sure if this is a good idea or not.   The glaze load I just ran at cone 5 went to cone 6 (cone bent all the way down, which I think is a little overfired?).  I was aiming for cone 6 so this is an improvement over what happened when I changed the offsets.     I found this         http://hotkilns.com/check-thermocouple-tip    on the website so I'm going to check my thermocouples too, but how can you tell if they are touching the ends of the tubes if you have to remove the tubes to check them?

 

Forum question - I want to talk about shelf placement in my shallow kiln.  Do I start a new thread for this?

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To get to the thermocouples you'll have to open the outer panel, disconnect the element feeder wires and thermocouple wires from the terminal strips, then open the inner panel. You'll see the porcelain thermocouple terminal blocks there. The thermocouples mount in the middle two screws, the wires in the outer 2 screws. Loosen the two middle screws and push the thermocouple ends in until they can't go in any more. Then tighten the screws back up.

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