Monday, May 25, 2009

Element Design for Electric Kilns

I'm in the process of designing new elements for my 3 electric kilns. 

For potters who do crystalline glazes, normal elements may last from 15 to 40 firings, and this means that we buy lots of elements, and that we spend lots of time changing them. But if an element is designed correctly, it will last for many more firings, and this was proven to me by redesigning the elements in my smallest kiln -- so far they have lasted 136 firings to cone 10-11. 

This redesign was the inspiration of my friend Jesse Hull. Steve Lewicki of L and L kilns actually did the calculations and made the new elements. It was a redesign of the whole kiln, as we now have twice the element wire as before, and it is much thicker -- gauge AWG 12 to be exact. 

The proper information to design elements is available online but it is much more complicated than at first glance. It's not as easy as it looks and you have to figure out basic parameters and then balance variables so that the elements work well. It would seem to be easy but it is not. However I am going to figure it out. 

This information is really essential if you do crystalline glazes but most helpful if you are anyone who wants to maximize the life of your elements. 

Before we get to the process of calculation -- and I admit that I do not have this all crystallized in my mind -- the most important variable is what is called watt loading. This is defined as how many watts per square inch of surface area do the elements have to generate. If they have to generate a lot of watts, they will not last as long. Bottom line. 

I wish it were this easy. Just design the kiln with thick elements and all is well. But it is much more complicated than that. Thicker elements have less resistance per foot, so we now have to have a longer wire to have the same resistance as before, and that longer wire may not fit in our kiln.

I am going to try to figure it all out and post it here. Dull subject but of great value. 


Anonymous said...

definitely not a dull subject... sounds like it's doable and not sure why manufacturer's haven't done it already (except the cynical built in obsolescence factor). i wonder if the standard thermocouple works just the same with the thicker and longer element?

Alex Solla said...

After talking with Stephen at L&L last week, I am sure you and he will come up with something that fits the bill. As for whether or not that will filter down to the avg kiln is doubtful. There has to be a need. By and large, octagon kilns are about economy. I priced out a DaVinci model at 20cu ft and it was just shy of $5K. That's a lot of beans. Wonder if maybe they could enable the DaVinci models to handle these higher watt-load elements?

Sure will be interesting to see what comes from your research. I dying to know how much more insulation (or LESS) Steve will recommend. Hard juggling all these variables!!