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Jeff Conti
06-13-2011, 12:37 AM
Any advice on checking the calibration / accuracy of my oven. I have an Even Heat. My wifes pottery kiln wasn't getting to proper temperature (she knew because her witness cones weren't drooping properly and her glazes weren't coming out). We swapped out the thermocouple and all is well. How do I know if my knife kiln is heating properly?

Knifemaker.ca
06-13-2011, 08:16 AM
I keep a second pyrometer for checking accuracy - as well as checking temps at different spots in the oven. Of course that presumes accuracy of the second unit. Witness cones are not helpful because they don't measure temperature. They measure heat work. Orton has another product called tempchek that may be useful, but I was less than pleased with my ability to get good results.

You could do go/nogo tests with something known. ie; pure silver melts at 1763F

Rob!

Justin King
06-13-2011, 08:43 AM
I use the Curie point (non-magnetic temperature) to calibrate mine. Steel (regardless of alloy) will lose magnetivity at 1414 F on the upswing. I heat the oven to 1400, place a piece of scrap in, let it equalize, and check it with a magnet. Then raise the temp 5 degrees and repeat. The only thing you have to watch for is once the piece goes beyond the non-magnetic point, it may not become magnetic again until well below 1414 F, so the calibrating has to be done working up to 1414 without over-shooting it.