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L&L JD18-JH Electric Kiln
In my attempt to acquire an electric kiln that could hold up to the repeated ^11+ crystalline firings I perform, I had the pleasure of configuring a design with L&L Kiln Mfg. president Steven Lewicki. The resulting JD18-JH was created to surpass the requirements for repeatable true ^10-11+ firings; however, it accomplishes much more than just higher levels of heatwork. The JD18-JH is capable of faster up-ramps and down-ramps, longer holds, and much longer element life at high temperatures beyond the norm of most commercially available kilns. To accommodate the requirements set for this kiln, Steve Lewicki and his staff developed the Quad Element Holder Design. This design offers better element potential in terms of wire thickness, watt density, and coil spacing, translating to longer element life and a greater use of power. *Follow this link to view more pictures of the new Quad Element Holder Design. Automated control using sheathed Type-S thermocouples offers a longer lifespan of accurate readings, while L&L's patented element holders allow for much easier element replacement. Having said that, I've performed over forty ^11-12 firings, with ohm readings, visuals, and firing graphs showing little to no degradation --so it looks to be a very long while before replacing the elements will even be necessary. The shell of the JD18-JH is comprised of 2500 deg. (K25) kiln brick throughout (rather than typical K23), forming 2.5" thick walls, 2.5" or 3" thick floor, and 3" thick lid. The thickness ratio of the brick has shown to accentuate thermal equilibrium within the kiln, by reducing the tendency toward hotter and cooler sections normally associated with many top loading electrics. The configuration also allows the kiln to cool more rapidly eliminating the "Achilles Heel" associated with many of the heavier insulated kilns on the market. Of course, if the user wishes to fire down slowly, then it's as simple as programming a slower ramp into the controller.
For more detailed information on why I bucked the trend and went with less insulation Click here. By keeping detailed firing logs, it has become apparent that the offset ratio of k25 shell, especially in conjunction with the zone control features of the Dynatrol (Bartlett Instrument's V6-CF 700 series controller) encourages even temperatures during faster ramps, and higher levels of heatwork without "hotface" deformation. It also allows for fast and even cooling out of those top temperatures (decreasing the effects of residual heatwork), yet still releases heat at a slower rate during critical phases such as quartz inversion and downward to 250°F, when dunting and crazing occurs.
I always gauge my peak temperature heatwork by using self-supporting witness cones. Therefore, a larger spy hole is currently in the works for this kiln. The goal is to accommodate the viewing of guide, target, & guard cones, allowing for precision firings beyond that of the computer controller. Capable of fully automated multi-ramp firings, the kiln controller allows for a manual override of peak temperature holds once the desired cone bend is achieved. |
L&L Quad Holder Element Design Images
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