|Monthly Tech-Tip |
We sometimes see customers doing this with cones: Putting them in the plaque backwards! Of course, they are not going to be accurate. Actually, self supporting cones are much better, they are idiot-proof because they enforce the 8 degree angle and bending direction.
Orton says “90 angular degrees is considered the endpoint of cone bending”. First, let's assume the normal: Examination of cones on kiln-opening to verify controller operation. Consider the cone on the left: The tip is touching. But it is also beginning to buckle, that means it was touching for a while before the firing ended . Who knows how long! The second one is not touching, but has still fallen a little too far. Why do we say that? The third one, positioned on the Orton guide, has reached the recommended 90 degrees. This demonstrates a good reason why self supporting cones are much better than standard ones: They are not touching when considered done. And standard cones, when sent in a 3/4" plaque, have a less consistent bending behaviour.
Devices that melt and bend in a ceramic kiln at specific temperatures when subjected to specific up ramps. Today, cones are used to calibrate controllers.