THE KILN SITTER
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The Dawson Kiln Sitter is an automatic shutoff used on manual-fire kilns. When a small pyrometric cone that is loaded into the Kiln Sitter bends, the Kiln Sitter shuts off.
THE KILN SITTER PLUNGER OVERHEATS
If the Dawson Kiln Sitter overheats, the white plastic plunger can get so hot that it melts. Ways to prevent this:
1) Make sure the high temperature washer on the porcelain tube is pressed against the firebrick kiln wall. A spring wire retainer keeps the washer in place. This helps prevent heat from escaping the kiln.
2) It is also possible that the wires connected to the Kiln Sitter contact block are loose or corroded, causing the block to overheat. This, in turn, overheats the plunger. Heating and cooling of the kiln can loosen the screws over time.
3) Another reason for overheating is that the wires connected to the Kiln Sitter contact block are too light a gauge.
4) Circulate air with a fan if the firing room temperature rises past 110 degrees F. (Measure room temperature about 3 feet from the kiln.) THE KILN SITTER PLUNGER DOESN'T STAY LOCKED ON
1) The plunger will not stay in unless you have time on the Limit Timer clock. If you have time on the clock, the Limit Timer may be burned up.
2) A wire may be in the way of the Kiln Sitter plunger mechanism, preventing it from locking in the on position. Sometimes heat causes a wire to move inside the switch box.
3) Something has fallen into the switch box and is interfering with the plunger: a matchstick, a piece of dried clay, a screw that has fallen into the switch box. If anything lodges where the contact blocks come together, the plunger will not stay locked on.
4) The locking catch is rusted or has material stuck to it.
5) The spring for the latch is broken.
Q. My digital kiln is taking too long to fire: 9 1/2 hours to cone 6. I want the kiln to fire in 4 hours.
A. 9 1/2 hours is the firing time programmed into the Sentry Cone-Fire mode at fast speed. The easiest way to go faster is to use Ramp-Hold mode, where you can program the exact speed that you want. Note, however, that the firing speed is limited to the kiln’s heating capacity.
Q. Can oils from your hands damage a new element?
A. Oils will burn off harmlessly the first time you fire the element. Salts can damage an element. However, the amount of salt on the hands is so small that it would have no effect on element life. But do not allow kiln wash to touch a new element.
Q. If an element burns out in the fiber roof of a GL-24 kiln, must the entire roof be replaced?
A. The fiber roof with embedded elements comes in three sections, which are placed side by side in the kiln. If one section burns out, only that section has to be replaced. You do not need to order the entire roof.
Q. I have programmed a cooling rate of 400 degrees F per hour, which should take 4 hours to cool down to 100 degrees F. Why is the kiln taking 7 hours to cool instead of 4 hours?
A. The controller's cooling rate is limited by the cooling rate of the kiln's insulation. If the kiln takes 7 hours to cool to 100 degrees, then the controller cannot speed up the cooling rate, even if you program a FULL rate.
The purpose of a controlled cooling is to make the kiln cool down slower than it would if you turned it off and allowed it to cool on its own.
Q. I have programmed a segment for flash venting, which takes the kiln down to the annealing range. I open the kiln to bring the temperature down, but when I close the lid, the temperature shoots right back up again.
A. If you flash cool the kiln by raising the lid, the rate for that segment should be FULL. If you have programmed a slow rate, the kiln will heat back up in an attempt to slow down the cooling rate.
Another possibility is that the elements turned back on because the temperature dropped into the next segment, which had a slower cooling rate.
Another point: Kilns are subjected to temperature rebound. If you opened the lid for a moment to lower the temperature, the temperature would go back up a little after you lowered the lid again. This would happen even if the kiln was turned off.
MY FAVORITE WEBSITE TOOLS
Hold down the Ctrl key while you turn the wheel on your mouse to change the type size of a web page.
Hold down the Ctrl key while you press F. A search box will appear. Type a key word into the search box to find that term on a web page.
In the last Kiln Pointer I mentioned the enthusiastic glass artists that I met recently while traveling. Joe Spitzer of Geneva, Florida wrote, “Your notes concerning the enthusiasm of the glass artists you visited reminded me of a quote from Charles Kingsley that has had a major influence on my life: ‘We act as though comfort and luxury were the chief requirements of life, when all we need to be really happy is something to be enthusiastic about.’”