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PCHPottery

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  1. Good question on the Dynatrol. Yes. The firing times for them are almost identical. We got the Genesis because there was not enough transparency with the Dynatrol. The Genesis has confirmed what I'd seen happening with the Dynatrol by sitting next to it for 90 minutes taking minute readings. I'd done this with the Dynatrol for various firing cycles in an attempt to understand what was occurring.
  2. Do you have an infrared thermometer you find most accurate and would recommend? Thanks so much for your help!
  3. Another issue is that without the current 35F offset, the kiln will be tasked with reaching 35 degrees higher. This will take a minimum of another 30 minutes. We did check the TCs and they are evenly placed into the kiln, not knocked out of place, or unevenly placed within the tubes.
  4. Thank you for the explanation. That makes complete sense. So if this is within tolerance, how would this kiln ever reach ^10, if it can't reach cone 6 temp without timing out for heat work in the final segment? Is it because it doesn't have 3" bricks? We believe that most of the voltage loss is due to the 60ft distance from my kiln to our panel. As noted above, we plan to change the wire to 4 gauge in the near future so that would fix the voltage issue. But would that small loss of voltage account for the difficulty the kiln is experiencing?
  5. We just measured all four elements individually end to end. All four were 10.9 ohms. The amperage measurement was taken with the kiln on. Do you know what the elements we installed are spec'd at in terms of ohms per element? Without the Tcos the orton cones were always overfiring to cone 7 with self-supporting cone touching the shelf. With what you're advising, that must be because of heat work due to slow rise at the end of the final segment.
  6. The following are results from my husband's testing of my JD18 kiln today. Thank you in advance for any guidance you're able to give! Idle configuration Two rings, both with two elements wired in series. Combined resistance of top ring 21.9 Ohms as measured from the plug to the controller while plug is disconnected. Resistance of bottom ring 21.8 Ohms, again as measured at the plug to the controller. Available voltage is 241V, measured at the main block inside the controller. Test Use program 12, Full Power Test, to turn the elements on full on and keep them there. Measurement point is now right at the block that the elements are attached to. For each ring, test while idle, as well as when relay is not calling for power, shows 0V. Under full draw, voltage moves from 241 down to 235 and settles there. All measurements made with quality digital multimeter. Ohm’s Law Based on these measurements, full power looks like: Resistance (Ohms) Voltage (Volts) Current (Amps) Power (kW) Ring 1 21.9 235 10.7 2.52 Ring 2 21.8 235 10.8 2.53 Total 21.5 5.05 Note that the data plate for the kilns says that it is: JD18 Serial 031802A Voltage 240 Phase 1 Amps 23.0 Watts 5520 Max temp 2350 Questions Is ~6V a reasonable amount of sag for a kiln switching between idle and full draw? I did check using a voltage drop calculator and 60’ of line at 240V and 23A of 10AWG should drop something around 3V. We are likely to replace this with bigger wire shortly, but even 4AWG drops 1V. So is this material? The kiln has brand-new elements, EJ18003H’s. The only way to get to 5520W, even at full 240V, would be for each element pair to fall closer to 20.9Ohms. Are these elements within normal parameters?
  7. I have a L&L JD 18 240-1 that I purchased new in 2002. Shortly after purchasing, my pottery life took a long hiatus. It's only been fired just over 30 times, a mix of bisque and glaze firings. I've recently gotten back into pottery and have been experiencing ongoing issues with reaching temperature at cones 5 and 6. The thermocouples have been replaced and are type K with the open ceramic sleeves that extend past the metal portion. I have a TCOS of 35 degrees F to account for the ceramic tube. I did this Based on advice from L&L tech support after over firing based on Orton cones without the offset. I've put in new L&L elements and replaced the Dynatrol with a Genesis 2.0 controller. The firing information coming from the Genesis has been great. I can now see that part of the problem is that the kiln is struggling to climb more than 65 degrees per hour during the last ramp section of a fast fire ^6 program. This cone 6 firing with the 35 degree offset produced Orton ^7 touching the shelf with glazes running. When I adjust the TCOS to achieve an Orton ^6, the offset is 55 degrees but the glaze is underfired. I'm assuming this is due to ^6 being achieved through heat work at the end of the firing instead of final temperature. Will this kiln not be able to climb the 108 degrees per hour at the end? Is it due to not having 3" brick? I've attached the firing file for a better description than I'm able to provide. Any help would be greatly appreciated! kiln firing graph ^6 Dec 12 2020.pdf
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