Oven Build Question

colu41

colu41

Joined
Dec 24, 2014
Messages
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So my oven is 99% complete. We plugged her in and it definitely gets hot. Problem is, we set it to 500, and it went all the way to 575 before it started to drop back down.
Is this a normal for new coils? Is there a wear in time for them? Or is this a programming thing? Everything else seems to be great. Holds heat great, and we set it to 800 and took just minutes. Just need to figure out this last little problem.
 
It takes a little bit for mine to even out when I'm tempering. Also, have you calibrated it? 400-500 is on the bottom end of what they are designed to do. It heats so fast at those temps it's hard to feather.
 
Ok. No we haven't calibrated it. Just the initial set ups. But just now temping at higher temps it seems to do a little better. Not shooting too much higher.
Is it not suggested to temper with these?
 
I'd calibrate it and see how it holds at higher temps. After some reading I no longer use my kiln for tempering. The temp fluctuates to much at the lower end because the relay has to kick on and it doesn't take much for your coils to soar past your tempering temps. It also takes my kiln a very long time to cool down after it hits 1000 plus. My kiln is 23" so you may have a different experience if yours is much smaller or larger.
 
Mines 6" square by 15" long. I'll have to do a little more research but. I'll have to temper in my typical oven.
 
One other thing I should ask. There were maybe 2 very small hot spots in the coils. Will this be ok? Or do I need to do something about that?
 
I'm guessing you've got a PID controller on it?

If so, running an Autotune should sort it out.

In most cases, the best approach is to run the oven to maximum working temperature before running the autotune (this gets a dark Oxide coating on the thermocouple and changes how it absorbs radiated heat slightly: you do not want to do the tuning run on a shiny new thermocouple because every other time it runs, it will have an Oxide coating). Run the tune from fully cold and tune it to the lowest (probably tempering) temperature you are realistically going to want to use it at.

The overshoot will always be much less at higher temperatures.

Get a notebook for your oven. Note down the P,I&D values the autotune gives you and the temperature you tuned it to. Then keep notes of everything you do in it.

The hotspots may or may not be anything to worry about. It's hard to tell without seeing them. Can you get pictures?

If they are thin spots in the elements, there's probably not much you can do about them except get a set of replacement elements on the shelf against the day they fail.
 
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