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Uhhhhhg I'm going to tear my hair out...I adjusted the thermocouple offsets, but now the cones bent even less. Is it possible that ditching the second slow cool ramp accounts for this, and I need to adjust the thermocouples even further?

And yes, still pinholes/blisters, but fewer still.

20210128_092509~2.jpg

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Just curious if you run a standard cone fire program and drop 100 degrees and hold for twenty or twenty five, at least you are trending correctly. I am really not a fan of tuning the tcouple when using custom programs. Always felt tuning them using the default cone fire program  was more consistent with respect to what the controller was designed for.

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49 minutes ago, Bill Kielb said:

Just curious if you run a standard cone fire program and drop 100 degrees and hold for twenty or twenty five, at least you are trending correctly. I am really not a fan of tuning the tcouple when using custom programs. Always felt tuning them using the default cone fire program  was more consistent with respect to what the controller was designed for.

Hmmmm...if I plan on using a custom program for firing (because of the aforementioned pinhole/blister problem), shouldn't I calibrate to that program? That's the assumption I've been working off of, at least

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Maybe, I always approached it as get the thing calibrated using the the built in cone fire programs then work your schedules as you like from there. Assuming the kiln is really accurate it allows you to develop a schedule that hits a cone. My assumptions are based on what I know about PID controls, teaching how to program them and the complexity of tuning the proportional, integral and derivative parameters. The control manufacture has to marry those with a typical power output of most kilns with the thermodynamics of the mass of ceramics and the kiln and  quite frankly many other things to control the process..... I am old and PIDs have been a fantastic solution for many years. Steamships to large 100k cfm fans to cement and wood kilns to you name it. In fact we used pneumatics mostly for analog or proportional control exclusively before digital achieved enough precision and speed to compete. For time delay or to slow a response  in pneumatics I simply change an orifice size. Pretty easy actually. Google PIDs and read how to program, most folks give up after 1/2 page of instruction.

Anyway, not fact just my experience, but consider our past custom schedules never allowed us pick a cone to end at - just a temperature. As a result we were always subtracting 200 - 250. degrees from the perfect peak and trying to hit 108 degree per hour to bend the cone correctly.

I believe by design the control needs to be most accurate using the built in cone fire table and the parameter table built into it. The more one moves away from that the less accurate the control becomes. It’s awfully difficult  to build a control for such a wide variety of firing instances. Lots of parameters to get right and adjust for. Not fact, but my experience.

The cone fire programs allow one to preheat, fire to cone,  and drop and hold as you like, just curious why you would not use them first actually. They should be by default the most accurate program in the thing, unless the thermocouples have been adjusted for other custom programs first, then maybe they are no longer.

Consider if you have two unknowns, it’s really hard to solve a problem by trial and error. If you have a kiln that fires reliably to a cone then adjusting the custom schedule  not the tcouple is the only thing you have to work on. Your baseline condition is more consistent.

Perhaps just an old viewpoint though .............. but I am old.

Edited by Bill Kielb
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