neilestrick
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Posts posted by neilestrick
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The floor is shot, but the lid doesn't look like it's going to last much longer, either. The bad news is that new lid and floor slabs cost about $300 each, plus shipping by freight, so it may or may not be worth that for such an old kiln. Also, if the outer steel band that goes around the floor slab also goes around the bottom section of the kiln walls, it can be a real bear to change out the slab, and may require some sanding of the bricks to get a new slab to fit. Duncan no longer makes kilns so you'll have to get a slab from another kiln company and it may not fit perfectly. Also, the new slabs will be brick, not fiber, so they'll insulate differently and the peak temp rating of the kiln may be lower. Post a pic of the serial plate so we can see what the wattage of the kiln is.
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9 hours ago, LIT said:
Any other thoughts or ideas?
Leave the TC offset alone and just program it to a higher cone.
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Hi @MD pottery, welcome to the forum! Is this a fiber floor or a brick floor? Post pics if you can.
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If you can't figure out the timer relay situation or can't get parts, you can just add one more 15 amp infinite switch, do away with all the relays, and wire each element set to one of the switches. If it were me, I'd go ahead and replace the old switch, too, so you're starting fresh with matching switches. Any 240 volt, 15 amp infinite switch kit will work. I like Robert Shaw brand. Make sure it includes the knob, because many don't.
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If the timer shut it off before the cone dropped, then it didn't reach temp. Turn the kiln on high for a few minutes and see if all the elements glow. If one is out, then it's probably just a fried element. If two in the same section are out, then you probably have a bad switch. Or in both cases it could be a wiring connection fried out somewhere, which should be easy to see when you open up the control box (with the kiln unplugged). If they all glow, then they're probably worn and need to be replaced. Post a pic of the elements so we can see their condition.
- Sylla, Piedmont Pottery and Pres
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Sounds like a relay got stuck 'on' so the kiln climbed very quickly. 1.5 hours is at least 4 hours faster than it should fire. As Bill said, it's probably a problem with one of the timer relays at the bottom of the control box. Figuring out which one will take some doing with a meter, and you may or may not be able to find a replacement part. It looks like your kiln has two groups of elements? The easiest and least expensive solution is to pull out the timer relays and add another infinite switch so that you then have two switches, and each switch controls one section of the kiln. Post a pic of the serial plate of the kiln, and a pic of the entire element connection area.
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@Mary Delmege Does it have a high limit controller on it? Post some pics of the burner system.
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@clayenthusiast Here's a recipe for Betty Woodman White, which is a very popular magnesium white that I've never seen have any problems on stoneware bodies. I used it for many years on my own work. Give it a try and see what you think.
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It's a calibration issue. Either do a cone offset for 04 or just program it to cone 03 instead. I believe that has the same controller as the Skutt kilns, so THIS instruction page should work.
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Also check the condition of the inter-box plug, if your kiln still has it. That can cause issues, too.
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I think it's probably permanent. Mixing and packaging dry glazes is a real hassle, so you have to sell a lot of them to make it worth the work. I expect that the vast majority of people who buy the PC glazes are getting wet mixed pints.
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23 minutes ago, BobMagnuson said:
Sorry I'm late to this conversation. I see 3 problems with this glaze. First, the clay content is too high, which can cause shrinkage and separation before firing. It might not be noticeable before firing , but can show up as shivering out of the kiln. Second, the coefficient of expansion is quite low, which could be an issue with some clay bodies. And finally, it looks like it might be applied too thick. The first 2 issues could be resolved by reducing the kaolin by 25% or so. (Run a few tests in that neighborhood.) Finally, if you're dipping your glaze, keep the specific gravity below 1.5. 1.45 works for me with a 5 second dip.
If the problem is the clay content, another solution would be to replace some (half?) of the kaolin with calcined kaolin. That way you can keep the chemistry the same while reducing the pre-fire shrinkage.
I agree. The kaolin, silica, and bentonite make up almost 50% of this glaze. There's just not enough fluxing going on there. I'm wondering if there was a problem with converting the recipe at some point since the numbers add up in a strange way. Maybe someone messed up the math?
- Roberta12 and clayenthusiast
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Definitely check out everything Bill recommends. If everything looks good, then I would replace the wires going into and coming out of the switches. If they're old they can cause overheating.
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On 5/17/2023 at 6:55 AM, Pres said:
Interesting how some folks seem to be trimming yet not aware of how they do the specifics.
Teaching did more to improve my throwing skills than just about anything else, because I was forced to analyze everything I was doing in order to explain it to my students- hand position, body position, pressure, how I was holding tools, tool angle, wheel speed, etc, etc, etc. It was especially great for consistency, because once I could define exactly what I was doing I was able to repeat it every time.
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@Forest River Pottery Typically the bottom and top work the hardest, and the middle works the least. The fact that the middle is running at 100% doesn't make much sense unless it's really early in the firing, in which case it's possible. I would check that all the thermocouple connections are secure. Make sure a TC wire hasn't broken under the screws in the TC block. Also make sure the middle and bottom thermocouple wires aren't swapped somewhere along the line. Typically that would cause an error pretty quickly, but ConeArt are kind of unique with the floor element and graded elements. Have you checked the resistance and/or continuity of the elements to make sure they're all correct and not broken?
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I agree with Bill. Keep the buss bars, replace the other hardware. Buss bars seem to last forever even as the rest of the hardware corrodes away. The little square washer things can be replaced with fender washers. Use stainless steel hardware for everything. The bolts are probably 10-24, but take a buss bar with you to the hardware store to confirm. Splitting the ends of the element pigtails to go around the bolt is a real pain, so if you want you can just bend the end of the pigtail to go around the bolt. Also put new ring terminals on the wires, or replace the wires if they're old. Use high temp ring connectors, not the regular ones you get at the hardware store. You can find them online from a bunch of places.
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I've always felt that charging a percentage of sales is good for a lot of the artists, but bad for the promoter. As an artist, it limits your costs if the show is a dud, and the percentage isn't necessarily penalizing unless you sell a lot of work. If you're someone who typically sells $5000 at a show, I can see how it's not a great deal compared to paying a flat $400 booth fee. But for someone who typically sells half that much it can be a good thing. I think you just need to do the math before applying and decide if it's a good show for you or not. As a promoter, only charging a percentage of sales makes no sense because your costs for running the show are the same whether the artists sell a lot or a little, and it adds a lot of paperwork to the process. Flat booth fees are easy to deal with and easy to budget.
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Pottery wheels don't typically need any lubrication since they use sealed bearings. Unless it has a grease fitting then there's noting to grease. Can you confirm where the noise is coming from- bearing, belt, motor? If it's the bearing, then the bearing is likely worn and should be replaced. If it's the motor, then it may just need a quick touch with a commutator stone (depends on what type of motor it has).
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On 5/16/2023 at 5:03 AM, Nadrali said:
It is a low fire raku glaze
Definitely not a good glaze for pieces that could be used for food, due to the crazing and poor durability. Raku glazes are generally formulated for a certain look, not for functionality. With low fire work you really want a glaze that fits really well if you're making functional work, or anything that is used around liquids, since the clay body doesn't vitrify.
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2 hours ago, moonzie said:
Ooo I like the idea of using a pair of mechanical relays connected to a safety output! Or maybe just a beefy double pole single throw relay. The SSRs I ordered are rated for 50a so they should run a bit cooler.
That Duncan is only a cone 8 kiln so I'll probably just use it mainly for bisque fires with the occasional/rare glaze fire for extra large pieces. Lots of elements to maintain. They all appear good but I've got a few new old stock parts on-hand it came with just in case. A part of me wonders if I'm going too far if this is going to be a mostly bisque kiln. I had to calibrate a kiln sitter once on my wife's first kiln (an old L&L from 1971) and I hated it lol. That kiln was never right after she over-fired it one summer.
Each section would have a mechanical relay and an SSR. The mechanical is turned on by the safety relay at the start of the firing and remains on until the firing is done. The SSRs are connected to the controller outputs 1,2 , & 3 and get cycled on and off by the controller. I've attached a wiring diagram for a Skutt SSR kiln, which is how it should be done.
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It will work, but put a washer on it that tightens up the hole. The screws are #10.
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2 hours ago, moonzie said:
It will have zone control yes. I've got a full size Genesis controller (the older one).
I might build a wall mount box. I might just put it where the kiln sitter used to be and use a case fan to circulate ambient air. Not sure yet! I suppose a wall mount would give me more modularity. It's big. ES1020-1 with the added ring on top.
I'd go wall mount. It'll be easier to work on and everything will stay cooler and last longer. The Duncan box will be a tight fit, and may not be deep enough for everything, plus you could use the wall mount on other kilns in the future. You'll still want a cooling fan in the wall mount, unless you have a large heat sink. A fan is much cheaper than a heat sink. The fan can connect to Output 4, or just run it in line with a power switch. Run mechanical relays in pairs with the SSRs, with the mechanicals being controlled by the Safety output on the controller and the SSRs run by the Outputs. Use very fast acting Type T fuses for each circuit. The SSR control for the Genesis can be turned on in the Factory Config menu, use code 443.
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Any of the type K 8 gauge thermocouples will work fine, whether L&L, Skutt, etc.
Are you building a wall mount box? Are you setting it up with zone control?
Question about Kiln in classroom.
in Equipment Use and Repair
Posted
The kiln will take 6-12 hours to fire up, then another 12-24 hours to cool depending on how big the kiln is and how much work is in it. So at best you have about 18 hours where it will be hot and could be a danger to the kids. Plus the vent will be running and that can be loud. So no, it's not ideal. That said, I work on a lot of kilns that live in the classroom and they seem to make it work just fine- by firing on days when they don't have a full schedule, or timing the firing so that it's hottest when the classroom isn't being used and it can cool overnight. Ideally it would be best to have it in its own room, but I get that that isn't always possible. By only working at low fire temps you can shorten both the firing time and the cooling time. At the very least you should invest in a safety screen like THIS. They're usually available through Blick and School Specialty, too. Another option to keep the kids away is to build a chain-link fence around it. Dog kennel panels work well.
How is the kiln vented?