On Wed, 17 Oct 2007 22:59:58 +0200, "Bubbles_"
wrote:


Thanks for your diplomatic view, Bob :-)

Marianne


Hmm, "diplomatic" is not something I'm often accused of!

Seriously, I think the point that folks are missing is that
a good kiln controller *does* take heat work into account.
By "good", I mean one that follows a specified time-temperature
curve, so that if you set it to (say) "hold at 1000C for an hour"
at one point in the firing cycle, the controller cycles the power to
the elements just the amount needed to hold at 1000C.
That part is no different from the "inifinity control" on an ordinary
electric oven.

But in addition to this, if you tell it to ramp at a certain rate, it
can adjust the power moment-by-moment to hold that ramp rate
(within some tolerance, of course). This is critical, because it
compensates for light or heavy kiln loads: If there is a light load,
the elements (if unregulated) would heat it up more quickly than with
a heavy load.

One can debate that the controller only knows the temperature
of its thermocouple, which is not the same as the pottery itself.
But on the other hand, the exact same argument applies to the
cone. There is nothing magical about the fact that the cone is
made out of a ceramic substance and therefore holds some secret
knowledge about other (wildly different) ceramic substances in your
clay and glazes. The cone is just a "cheap and dirty" way to get an
estimate of heat work. Before the advent of computer controls,
it was the best show in town. Now, I think it is more like a security
blanket if you already have a computer controller. Barring things
like power outages that might confuse a controller, I you could have
only one or the other the controller wins hands down, every time.
After all, the cones only tell you about end-points, they don't allow
you to program cooling soaks for crystal growth, etc.

But I have a big box of number 6 cones, and they make dandy
sacrifices to the kiln goddess!

Best regards,


Bob Masta

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