Cress Kilnsitter Graded Element question

[jay_klay_studio]

Quick question for anyone that knows (or has an educated guess). I bought an Olympic Electro Sitter for my Cress Firemate. Currently firing now and the kiln was having a tough time reaching the set point at the beginning (was about 20 deg off) but seems to be keeping up just fine now. I know that the kiln has a graded top/bottom vs middle elements. Question is, does anyone know when the middle elements kick on, or how that works? Is there a special relay that eventually distributes full power to all elements at a certain temp? Or is it likely more of a set ratio through the whole firing (i.e. 75% of power to top/bottom, 25% to middle or something like that)?

[Bill Kielb]

The electro sitter expects to turn all the elements on 100% and off 100%. So having other controls interrupting things is just confusion. Normal procedure is to turn all the kiln controls to high or full on and let the electro sitter manage the firing. The firemate should go to maximum or 10 and depending on your model any other kiln control you have turned up to high.

To answer the question of how it works, a timer motor slowly turns up a standard infinite switch. So the infinite switch cycles on and off proportional to its setting (likely starting around 22% and somewhat linearly to 100% power within prox 330 degrees of rotation) …….  and the timer motor ramps this setting upward over some amount of time. Generally the most confusing thing for most folks but an early attempt at semi automation.

Edited November 23, 2023 by Bill Kielb

[neilestrick]

Graded elements means that the middle elements have a different resistance than the top/bottom, so the mids don't run as hot as the t/b. Some kilns even have 3 different elements in them. The controller doesn't alter the power to them in any way unless the kiln has zone control, where each section of the kiln has its own thermocouple and is controlled independently of the others.