Fiona B Posted October 23, 2023 Report Share Posted October 23, 2023 Hi, thought I would see if the hive mind can point me in the right direction. I have an electric Rohde 43l kiln with standard controller fyi but I think the issues I'm having are with universal parts. I recently changed all the elements, which went smoothly and they all work, light and heat up. So far so good. The issue I have now is using the exact same bisque and glaze fire pre-programmes, the cones (I use witness cones) in my firings which standardly were a solid cone 04 for bisque and cone 7 for glaze before my element change are now different. My glaze firing is producing a hot cone 8 (Cone 9 just starting to bend). I can appreciate that potentially the elements being new may need some adjustment, so I did that and dropped both the top temp and the hold down for less heatwork. This changed nothing with the cones, it was still a hot cone 8. The bisque has me more confused. I presumed that would be over, however, with the same Cone 04 programme, and cones 05,04,03 in the kiln, none of the cones bent at all, indicating a lower than cone 05 temperature. All the bisque pieces looked fine and obviously cooked enough that I am happy to continue and glaze. I need to work out what is happening. I am fairly sure it is not the thermocouple. Rohde kilns have good ones and I spoke to the UK main Rohde supplier who said in his 25 years he had only needed to replace 6 thermocouples. Not very familiar with relays? Anybody any thoughts it would be much appreciated. Thanks Fiona Quote Link to comment Share on other sites More sharing options...
neilestrick Posted October 23, 2023 Report Share Posted October 23, 2023 What type of thermocouple? What firing schedules are you using? Fiona B 1 Quote Link to comment Share on other sites More sharing options...
Fiona B Posted October 24, 2023 Author Report Share Posted October 24, 2023 Sorry Neil. I replied to you last night but it doesn't seem to have posted. I cannot find any decent info online ass to a number or type ('k' or whatever). I can only find a spare parts (https://www.rohde.eu/media/pdf/c8/f5/cf/2020-Preisliste-KH-Ersatzteile_EN-web.pdf - page 9). My bisque is: Celcius: 50ph 100 83ph 600 133ph 800 72ph 980, 20 min hold Glaze fire: 90ph 300 115ph 1060 100ph 1220, 20 min hold. Someone elsewhere mentioned relays, it seems to be switching it on and off okay and time for firings are okay. Still a bit stumped. I have just borrowed a controller and put on another glaze firing to see if i can gain any more info... Thanks for your reply, Fiona Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted October 24, 2023 Report Share Posted October 24, 2023 (edited) Just to suggest to try ending at the rate published in the Orton chart if you are using Orton cones without a hold unless you want additional heatwork to move to the next cone. So cone for cone 04 go 60 deg. Per hour in the last 100c. cone 04 from chart : 1063c Last hundred starts at 963c last segment = 60 per hour starting at 963 and ending at 1063. The final 100c of the firing is generally where things mature to cone and Orton has tested their cones to operate this way. Just following the chart may improve your results significantly. Edit: I should add here I would use the center rate or 60c per hour. Many kilns fail or eventually fail to achieve much higher, for which unless you are timing and calculating the rate, really messes with the correct endpoint. It can lead to what appear to be random results especially between bisque and glaze firings. In North America we have a popular automatic controller that actually detects if things are going too slow and will display as an error. So unless you are checking time and temperature for the last hour to hour and one half, it’s hard to know what speed it is achieving really. The 60 c column seems to be a more dependable ending speed most kilns can achieve with reasonable elements. Edited October 25, 2023 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
neilestrick Posted October 24, 2023 Report Share Posted October 24, 2023 6 hours ago, Fiona B said: Glaze fire: 90ph 300 115ph 1060 100ph 1220, 20 min hold. I'm with Bill. Lock in the firing schedule so it matches the cone charts. That way you'll have a baseline to compare against. Start with firing all the way to the cone you're trying to achieve. Add holds after that to dial it in. Your 20 minute hold is equal to roughly one whole cone. Kilns often behave differently with new elements, but this is definitely a little odd. My gut says it's a thermocouple issue, but it's hard to say. Based on that link it looks like you have a type S thermocouple, so it probably does not need replacing unless you bumped it. Also check for loose wires along the thermocouple system. Quote Link to comment Share on other sites More sharing options...
Babs Posted October 25, 2023 Report Share Posted October 25, 2023 Is it pos with your bisque you put Cone 4,5,6 instead of cone 04,05,06? How did your bisque take tthe glaze? If below cone 06, as you have indicated, then it would suck up the glaze resulting in a different glaze thickness. Quote Link to comment Share on other sites More sharing options...
Fiona B Posted October 26, 2023 Author Report Share Posted October 26, 2023 No, definitely right cones. Haven't glazed as yet, this weekend. I’m just waiting on opening another glaze fire with pre-glazed pieces from before element change. I’ve changed the controller and schedule right now to get some more information, so we’ll see. I’ll do another bisque soon and look at that schedule. It’s the lower bisque that is throwing me but hopefully the bisque done will take the glaze okay, they look and feel no different than usual, perhaps more dusty. We’ll see if they act differently. Still perplexed! thanks for the input. Quote Link to comment Share on other sites More sharing options...
Babs Posted October 26, 2023 Report Share Posted October 26, 2023 6 hours ago, Babs said: Is it pos with your bisque you put Cone 4,5,6 instead of cone 04,05,06? How did your bisque take tthe glaze? If below cone 06, as you have indicated, then it would suck up the glaze resulting in a different glaze thickness. 3 hours ago, Fiona B said: No, definitely right cones. Haven't glazed as yet, this weekend. I’m just waiting on opening another glaze fire with pre-glazed pieces from before element change. I’ve changed the controller and schedule right now to get some more information, so we’ll see. I’ll do another bisque soon and look at that schedule. It’s the lower bisque that is throwing me but hopefully the bisque done will take the glaze okay, they look and feel no different than usual, perhaps more dusty. We’ll see if they act differently. Still perplexed! thanks for the input. Did you have a bank of cones on each shelf? Quote Link to comment Share on other sites More sharing options...
Babs Posted October 26, 2023 Report Share Posted October 26, 2023 (edited) Do you keep a log? Edited October 26, 2023 by Babs Quote Link to comment Share on other sites More sharing options...
Babs Posted October 26, 2023 Report Share Posted October 26, 2023 Can you read back, or have logged the actual temp reached/ hr? Does the controller signal an error code? Quote Link to comment Share on other sites More sharing options...
Babs Posted October 26, 2023 Report Share Posted October 26, 2023 On 10/25/2023 at 3:23 AM, Fiona B said: Sorry Neil. I replied to you last night but it doesn't seem to have posted. I cannot find any decent info online ass to a number or type ('k' or whatever). I can only find a spare parts (https://www.rohde.eu/media/pdf/c8/f5/cf/2020-Preisliste-KH-Ersatzteile_EN-web.pdf - page 9). My bisque is: Celcius: 50ph 100 83ph 600 133ph 800 72ph 980, 20 min hold Glaze fire: 90ph 300 115ph 1060 100ph 1220, 20 min hold. Someone elsewhere mentioned relays, it seems to be switching it on and off okay and time for firings are okay. Still a bit stumped. I have just borrowed a controller and put on another glaze firing to see if i can gain any more info... Thanks for your reply, Fiona When you turn on the kiln your controller may flick through a couple ofessages one of those, on mine is the thermocouple type, mine reads before I touch the buttons :Fail, tcR which is the thermocouple Type R. Then I go to the programme I want. The manual you need,if you haven't got one , is for the controller, not the kiln. Good luck, very frustrating. Quote Link to comment Share on other sites More sharing options...
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