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TonyC

NEW RESULTS: L&L CNOS Adjustment Needed?

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I have the following:

2007 L&L e23S-3 kiln with Dynatrol 700.   Changed elements and thermocouples ~1.5 yrs ago, but only ran kiln 6 times since then (moved and had to rewire new house).

Recently slow bisque fired to Cone 06.   CNOS was adjusted to 9020 due to previous "hotter" firings (based on previouys actual cones).   I checked cones after this firing and the Cone 05 had bent some (see pic - Cone 05 left, Cone 06 right), and the Cone 06 was completely bent over.

Per the system, final temperature reached was 1804 F (with 20 degree offset = 1824 F).   Per the Orton information, the Cone 05 at the 1 3/4" height is equivalent to 'self supporting' data or 1888 F (cone 06 = 1828 at this height).    

QUESTION:   Is it okay for the kiln to demonstrate this kind of offset between thermocouple readings and actual?    I don't know how to interpret the latest Cone 05 bend, and how to correct the system for it.   Should I be offsetting 30 degrees or more?   BTW:  I had checked the kiln after reassembling it in the new house, and I know the thermocouples were pushed to the end of the ceramic tube.

I will welcome any help or additional questions.  Thank you.

Tony

 

2019-01-05 Cone Bisque Firing.jpg

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I'm not getting how those cones were placed in the kiln. Are those small or large cones and were they in a cone plaque?

edit: page 8, how to make a cone pack. 

Edited by Min
added link

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Yeah that's interesting, but using the cones like that won't give you an accurate reading, they need to be vertical at the angle indicated by the bottom, gravity has too much say when they're placed horizontally and it would be hard to tell when they've tipped

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25 minutes ago, liambesaw said:

Yeah that's interesting, but using the cones like that won't give you an accurate reading, they need to be vertical at the angle indicated by the bottom, gravity has too much say when they're placed horizontally and it would be hard to tell when they've tipped

Oh.   I have only put the cones in this way.  Ughh.   I put them in exactly as the picture shows.   All are basically at 3 o' clock (side view) going into the kiln.   I thought this would be okay.   "Min" above has added a link for a proper cone pack.    I better do it that way next time.    

 

For now, should I not trust that the kiln is 'too' hot?    I guess I won't know until next firing.

 

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3 minutes ago, TonyC said:

Oh.   I have only put the cones in this way.  Ughh.   I put them in exactly as the picture shows.   All are basically at 3 o' clock (side view) going into the kiln.   I thought this would be okay.   "Min" above has added a link for a proper cone pack.    I better do it that way next time.    

 

For now, should I not trust that the kiln is 'too' hot?    I guess I won't know until next firing.

 

Correct. You need to fire again with the cones set properly.

It doesn't matter what the temperature readout on the controller is. It only matters that you're getting the correct results. If that means cone 05 is bent perfectly but the readout is 20 degrees off from the Orton chart, that's fine.

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35 minutes ago, Min said:

I'm not getting how those cones were placed in the kiln. Are those small or large cones and were they in a cone plaque?

edit: page 8, how to make a cone pack. 

Min, it looks like I completely messed this up.   The cones were simply layed out sideways as in the photos (with the exception of the bending).    Someone told me this would be okay, but it appears not.   I reviewed your link, and will be sure to do it this way next time.   I am so glad that I asked.   Thank you for the feedback.   

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2 minutes ago, neilestrick said:

Correct. You need to fire again with the cones set properly.

It doesn't matter what the temperature readout on the controller is. It only matters that you're getting the correct results. If that means cone 05 is bent perfectly but the readout is 20 degrees off from the Orton chart, that's fine.

Thanks for the feedback.   My next firing should be glazing, but now I'm concerned that the kiln may not be best calibrated.   I wonder if I should consider bisque firing again.   I have less to lose that way.

 

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You have to remember that TC offsets affect every temp, but cone offsets affect only that cone. I would put everything back at factory defaults and do test firings with cones at both bisque and glaze (assuming they're different cones), and then determine which adjustment should be made.

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1 hour ago, neilestrick said:

You have to remember that TC offsets affect every temp, but cone offsets affect only that cone. I would put everything back at factory defaults and do test firings with cones at both bisque and glaze (assuming they're different cones), and then determine which adjustment should be made.

Just to add , test firing an empty kiln is ok, but you will need to test fire under loaded condition as well. Self supporting cones make this easier to do as it ensures they are initially set at the correct angle. Cones are made of glaze about six cones less than their firing temperature so as they soften gravity pulls them down.

as Neil said  desired results are most important, so as long as you are not significantly under or overfiring most folks put the greatest importance on experience and  the intended result for their glaze / work product.

Edited by Bill Kielb

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I fired the kiln this weekend for cone 6 glazes and have some results which prompt more questions for me.    I used self supporting cones this time.

       Setup:  Fast Glaze, Cone 6, 2232 F, No CNOS or TNOS adjustments, no Hold

       Final Reading:  2263 F, Total Time 4 hr 58 min,  Actual cones bent 5,6 AND 7 (See Pic)

I am confused that my final reading is so high.   Shouldn't the system have stopped at 2232 F?    My Hold time was set at 0.     As you can see, the Cone 7 is completely bent over (left to right - 5,6,7; front row - top shelf; back row - first shelf).    

Can anyone help explain?   Is there a software problem in shutting down the system at the right time?   If not, then how much should I be adjusting the CNOS?   Since both shelves appear to show similar cone results, I assume to leave the TNOS alone.     Thanks for any feedback as I get to know this kiln better.

2019-01-19 Glaze Firing - Cone 6.jpg

Edited by TonyC
added cone info

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This is not uncommon and on FAST GlAZE which is less accurate.  Some things that affect this

  • the kiln was loaded  with lots of wares
  • the shelving was spaced so as to restrict the radiant energy, ( not offset)
  • The kiln exhaust pulls  more air or through the course of the entire firing
  • the shelves are a tad large for the kiln with only 1” or less spacing between the wall and shelf.
  • many shelves installed for low flat wares
  • the elements have a considerable number of firings on them
  • kiln voltage calibration is not current
  • kiln calibration has not been done for cone value offsets

 

automatic controllers are great but not infallible. The difference between cone 6 and cone 7 is 30 degrees if fired at 108 degrees per hour in approximately the last 250 degrees of firing.

Quetiinsmto be answered

  • how long did you Fire?
  • how many firings on the elements?
  • how well packed was the kiln?
  • single zone or multi zone control ?
Edited by Bill Kielb

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Did you put everything back to factory settings? You should do that before changing anything else. There should be an 18 degree thermocouple offset to correct for the insulating effect of the protection tubes.  From L&L: If you have Type K thermocouples and there is a ceramic protection tube then the Thermocouple Offset should be typically be set for 00.18 (18 Deg F).  Also make sure your thermocouples are touching the ends of the tubes, otherwise they're further insulated from the heat.

You'll need to determine if the kiln is firing hot at all temps or just at cone 6. Run a bisque with cones. If it's also hot, then you should do a TCOS. If it's only hot at cone 6, then do a CNOS.

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2 hours ago, Bill Kielb said:

 

Quetiinsmto be answered (SOME WERE ANSWERED ABOVE)

  • how long did you Fire?  4 hr 58 min
  • what was the ending temperature on the display?  2263 F
  • how many firings on the elements?  Few.  Maybe six  cone 06 bisques and two cone 6 glze firings
  • how well packed was the kiln?  Lightly packed.  Bottom shelf  6 mugs and a bowl.  Top: 5 chalices and larger pot/vase

 

I will go take a photo of the kiln shelves.   This is an L&L e23S-3 kiln.   I bought it used, and these shelves came with the kiln.    Can you explain your "offset" shelves comment?   I am not sure if I understand what you are referring to.   Thanks.

 

2019-01-19 Kiln Bottom Shelf.jpg

2019-01-19 Kiln Top Shelf.jpg

2019-01-19 L&L e23S-3.jpg

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2 hours ago, neilestrick said:

Did you put everything back to factory settings? You should do that before changing anything else. There should be an 18 degree thermocouple offset to correct for the insulating effect of the protection tubes.  From L&L: If you have Type K thermocouples and there is a ceramic protection tube then the Thermocouple Offset should be typically be set for 00.18 (18 Deg F).  Also make sure your thermocouples are touching the ends of the tubes, otherwise they're further insulated from the heat.

I am using the Type K thermocouple which I know needs the 18 degree offset which I understood to be compensated for in the system when the CNOS display shows 0.   I don't know if things are back to factory settings.   When I programmed this,  the CNOS was displayed at 0.    I assumed 0 already incorporated the 0.18.   Does the factory setting display actually display 0.18 when I toggle through the settings?    

I don't ever remember seeing a display of 00.18 at any of the Cone settings.   However, I might add that I bought the kiln used, and never considered that the previous owner may have changed settings (which I assumed were default).   

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7 minutes ago, liambesaw said:

Wow, 5 hours to cone 6, that's fast!

I have attached the Fast Glaze Firing Profile which I just noticed shows 200F/hr for the final segment (not the 120F/hr).    Would that have impacted the Self Supporting cones????   I thought I read somewhere that the SS cones were developed to bend at 120F/hr rate.    Ughh.

2019-01-19 Kiln schedule Fast Glaze.jpg

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13 minutes ago, TonyC said:

I am using the Type K thermocouple which I know needs the 18 degree offset which I understood to be compensated for in the system when the CNOS display shows 0.   I don't know if things are back to factory settings.   When I programmed this,  the CNOS was displayed at 0.    I assumed 0 already incorporated the 0.18.   Does the factory setting display actually display 0.18 when I toggle through the settings?    

I don't ever remember seeing a display of 00.18 at any of the Cone settings.   However, I might add that I bought the kiln used, and never considered that the previous owner may have changed settings (which I assumed were default).   

Factory setting have the TC offset set at 18 degrees. The controller is not already compensating for the 18 degree TC offset. This controller is just a Bartlett V6-CF controller with a different name on it, so not every kiln that uses this type of controller has thermocouple protection tubes. Therefore the 18 degree offset has to be programmed in for each thermocouple. The TC offset should not read zero. That will account for a lot of the overfiring you're seeing.

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5 minutes ago, liambesaw said:

Exactly

So could this mean that my cones bent due to rate of temp change and not necessarily too high a temp?   BUT, my final temp reading in the kiln was 2263 which was 30 degrees higher than the program.

 

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1 minute ago, neilestrick said:

The controller is not already compensating for the 18 degree TC offset. This controller is just a Bartlett V6-CF controller with a different name on it, so not every kiln that uses this type of controller has thermocouple protection tubes. Therefore the 18 degree offset has to be programmed in for each thermocouple. The TC offset should not read zero. That will account for a lot of the overfiring you're seeing.

SO I need to see the TC offset.   How do I get to that?   That is not cone specific but system specific, right?   I need to toggle within the "Other" menu if I remember correctly.   I will check this and see what if listed.

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1 minute ago, TonyC said:

So could this mean that my cones bent due to rate of temp change and not necessarily too high a temp?   BUT, my final temp reading in the kiln was 2263 which was 30 degrees higher than the program.

 

With the TC offset not correct, it's going to overshoot by approximately 18 degrees regardless of rate. When the elements shut off, they still radiate for a short time, and with an empty kiln there's nothing to absorb the heat and keep it from climbing higher. Get the TC offset corrected, then fire the kiln with some pots and see what happens.

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Probably the fast fire coupled with your tc offset, looks like you're just about there.  Firing the cones too fast can make them behave a little weird.  I've had a cone 6 barely touch and a cone 7 almost flat before from accidentally opening my flue and rocketing the last 300 degrees.  The whole 120/hr thing is pretty important

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7 minutes ago, neilestrick said:

With the TC offset not correct, it's going to overshoot by approximately 18 degrees regardless of rate. When the elements shut off, they still radiate for a short time, and with an empty kiln there's nothing to absorb the heat and keep it from climbing higher. Get the TC offset corrected, then fire the kiln with some pots and see what happens.

Darn.    I just checked and the TCOS setting and both thermocouples were set for FOS 18 (see pic for T1).    I thought I had this right, and also just remembered that it explained why my room temp always displayed higher than the actual room temp.    

I still need to double check that the thermocouples are pushed right to the edge of the ceramic tube.   I checked once before, but I need to confirm it since it will clearly force the system to run hotter.   I still struggle why the system got ~30 degrees hotter than the shutoff temp of 2232F.     

As for the actual cones, I need to lok up the info on their bending based on a faster heating rate (200F/hr) associated with the fast glaze.   

TCOS.jpg

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Regarding Witness Cones:   The box states, "Faster firings require higher temperatures for cones to bend."

I think that makes my situation even worse.   This means that the witness Cone 7 bent although it needed to see higher temps in order to bend.   Did this system fire above Cone 7?   The cone 7 was quite a bit bent over based on my photos above.   

 

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