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Callie Beller Diesel

If One Does Not Possess A Firing Gauge...

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I presume you are asking about the things needed to properly adjust a kiln sitter. The item described as a firing gauge is a round metal disk with a hole in the middle area and two angled notches in the sides. It is designed specifically to slip over the cone rests and the sensor rod on the inside of the kiln sitter and hold the sensor rod in exactly the right place when it should release the drop weight on the outside. Because it is designed specifically for this task on this product, there is no common tool-box item one could use in its stead. You would need to order one from any of the usual online vendors or your local pottery supply house may have them. They are inexpensive.

 

As for the other adjustments once the firing gauge is in place, the claw must set with a 1/16 inch gap from the plate of the drop weight, but the drop weight plate must just barely clear the claw. That is hard to set all in one swoop. I have found it easier to raise the drop plate so it is caught behind the claw, then adjust the claw for the 1/16" gap, and then lower the drop plate until it just clears the properly adjusted claw. For the gap, you could use a standard feeler gauge, or if you don't have one of those, just pick up a common 1/16" twist drill bit at the hardware store and use that as a spacer between the raised drop plate and the claw.

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I am talking about a firing gauge, and I know what one is, yes.

 

After years of firing at my local arts centre, the electrician is coming Friday to hook up my very own kiln!

 

My new-to-me kiln has been in storage probably for a good 30 years, and from the looks of it, has only been fired a small handful of times before that. Along the way, one of the rests for the cone sitter got lost, along with the original firing gauge, and I suspect the ceramic tube the apparatus sits in may have shifted at some point, just from the look of it. (the tube seems more recessed than the one on one of the kilns I was using previously.) I have replacement rests in hand, and was reading up on some of the older topics regarding cone sitters, as my kiln predates public internet. I have a firing schedule worked out that gets the results I want in the arts Center kiln, which was a lovely new programmable Skutt (thermocouple; no sitter) and I'm trying to figure the best way to make the same thing happen with less technical equipment. I figure making sure all components are in good working order, and adjusted to a baseline is a good place to start. I was hoping not to have to drive out to the supplier boondocks again for extra parts before Friday. But one does what one must :).

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Yes, little seemingly useless things get lost, and the cone supports fall out when moving it. Been there done that. If you have a replacement support, slip it in and see if the claw still holds the drop. It is probably ok if the kiln has not been fired much, even 30 years ago. The parts don't go out of alignment just sitting; it is the repeated minor impact when it drops at the end of every firing and heat/corrosion of the sensor rod over time that causes it to bend out of place. I doubt the sitter tube has shifted. It protrudes into the kiln by different amounts depending on the brand. As long as it is an inch or so into the kiln, it should be ok. Load it up for a bisque firing and put some cone packs around inside and fire it to see what happens. While we might like our bisque firings to be precise, the reality is that some minor error probably won't affect the work in  a bisque firing as much as it might in a glaze firing. As Neil noted above, the mini-cone should be bent to a right angle when the sitter drops. You can adjust by eye from there, as well as make judgements based on the witness cones. In the meantime, you can order a firing gauge from one of the usual suspects, and if you can, find and order some pyrometric bars in the appropriate cones. The mini-cones are most commonly used, but have some built in inaccuracy from the triangular shape. If it is a little off center, the sitter will drop early or late. The square bars can be a bit off center and they are designed to bend at a slightly higher heatwork to account for the additional heat flowing up and down the unobstructed kiln wall vs. across the shelves.

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I use a mini bar in my cone sitter as they seem to work better than the mini cones. I only bisque fire. The bars are more accurate I read .

I would just have your supplier drop one in the mail for you. forget the drive.They are flat like a penny (in US).

The other adjustment is the claw and Dick covered that well above.

 

They do come with a new sitter tube as well or at least with the whole assembly. I saw mine in that package as I keep a spare everything.

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