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Old 07-21-2010, 06:13 PM
Justin Thompson
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Pete.....

Thank you for the info. I was actually not thinking in terms of melting cycles as it effects the life of the pot. I know that makes me sound ignorant; however, in this case...I guess I am. To think of a pot's life in terms of melting cycles; it makes a lot more sense and helps me to think in a different way. As I said, I am pretty new to owning my own studio and being responsible for things like this. My experience with pot furnaces has always been 200lb and above sized pots, and those usually experienced a death as a result of pitting and detereoration. I haven't had much experience with cracked crucibles.

The information that I left out.....

I run a wiremelter (an AIM 1411) and the pot sits about 2.75-3 inches away from the element groove (so about 3-3.25 inches away from the element itself). I have added a layer of soft brick to the sides, so that the elements aren't sitting 1.5 inches from the floor of the furnace (a very poor design IMHO). Because of the added layer of 2300F brick, I have had to elevate the pot about 3 inches off the floor.

I keep the furnace idled at 1900 when not working. When working, I ramp it up (usually over 1.5 hours) to 2160. The furnace stays at 1900 (or above) 24/7. Since I am mainly teaching and doing about 2 days of small production, I find myself charging about once every 4-5 days. During the melt, I ramp it up to 2200 (usually after a day of blowing, so the furnace is already at 2160). BTW, I melt System96 nuggets. I charge at 2200 (usually about 8 lbs/charge cuz of the size of the pot). After the charge, I ramp up to 2300 and soak for 4 hours. From 2300-1900, I run an 8 hour ramp down.

When I have had to turn it down to do maintainance, I usually ramp the pot down over about 4 days. I, of course, ramp it down with a fully empty pot. I pay special attention to the pot during its ramp from 1400-800, usually with a hold and soak at 1400 (for 10 hours) and 1000 (for another 10 hours). I do this because I have been told that the pot is most fragile (to heat) in the range from 800-1400 degrees. There was only one time that I wasn't able to fully empty a pot before a turn-down. I blew an element (on the old 1411's, there are only two sets of elements, so one element isn't able to sustain above 1600). So, I came in to find the furnace at 1600, with about 1/4 pot full of glass. Since I didn't have a torch small enough to fit in the peep hole, I had to ramp the pot down being 1/4 way full. Again, I was careful to ramp down between 1400-800.

The furnace pretty much stays on 24/7 for about 4 months at a time (my elements usually have a life of 4 months), then I need to ramp down to switch out. I have been pretty good at being able to catch the elements in time, before they pop and am forced to ramp the furnace down, as is.

I hope that you don't find my knowledge (or lack there of) too comical and can offer a bit of advice on the ramping schedule for both charging and for the turn-down for maintainance.

Thank you.
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