neilestrick
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Posts posted by neilestrick
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5 minutes ago, mattb said:
looks like you beat me to the punch on the chimney question. what kind of cfm would you suggest if i were to build or just purchase a power burner? I'll most definitely be researching this probably before you answer back, but hey it feels more personal getting an answer than just reading things.
also if i move to a single burner how would you suggest my layout change for even heating?
CFM of the blower will depend on the btu output needs, but for something small like this a little 50cfm squirrel cage blower would probably work. You'll want to have a rheostat on it to slow it down. The nice thing about a power burner is you can resize the gas orifice and get a really wide range of output without making any significant changes to the setup. If you really want to make it safe, put a solenoid on the gas line and connect to it a high limit shutoff, in addition to the Baso pilot system.
This is one of a pair of burners I built a long time ago for a gas kiln I no longer have. About 450K btu each. Baso, solenoid, rheostat, high temp shutoff, timer. About as safe as I could make it with off-the-shelf parts and without getting into complex and expensive control systems. These can get pricey by the time you buy all the parts, but they work well and are quite safe.
Ward Burner Systems is a good resource for burner info.
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The size of your burner ports will depend on the size of your burner tips. The port should be about an inch wider in diameter than the burner tip. The end of the burner should be set back from the kiln wall 1/4" for every inch of burner tip diameter.
I don't know how you'll make a bag wall that's only 1" wide and stay standing. Typically the bag wall is made of hard brick, set on side, so 2-2.5" in order to be stable.
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5 hours ago, mattb said:
It might be easier to understand if a pic of the kiln was googled.
I've seen that kiln, which is why I don't think the electronics bay is suitable for the burners. It's probably too shallow to house the burners, and I don't know how you'll be able to get to them to make adjustments during the firing if they're enclosed. Plus you don't want anything to restrict air flow around the burners. I would cut out a big panel from the right side of the cabinet from kiln floor level to the top so you have a nice open space to work within. Make the chimney a full brick thick (4.5"), and put in a damper about 1/3 of the way up from the bottom.
5 hours ago, mattb said:baso valves seem to be the way to go and I will do more research before making final decisions on plumbing the burners.
Baso with a simple thermocouple and pilot light like an old school water heater will work well and be a cost-effective safety system.
5 hours ago, mattb said:I built my own n/a burners for my gas forge so I'll need to dig out my old notes and I may build my own.
Just thought- if you make a power burner (with a blower) you'd only need one, and it would also eliminate the need for a very tall chimney. The chimney height is the number one issue we see here on the forum when it comes to successfully firing converting kilns. Most of those use venturi (n/a) burners, which are cheap but require a good dose of secondary air to fire properly, which comes from a taller chimney. With a power burner the chimney doesn't need to be any taller than the top the kiln. Having the front wall of the controller cabinet would also allow for mounting a rheostat for the blower.
This kiln is a much better candidate for conversion than the majority of kilns we see here. It should work well.
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Hi @mattb, and welcome to the forum. It would help if you could draw a picture of your plans. Here are some questions I have based on my understanding of the project:
You're making it a downdraft, correct?
What is the btu output of your burners? Powered burners or venturi? Natural gas or propane?
What are you using for a safety system on the burners- Baso valve?
Why do you want to run everything through the electronics bay? Seems like a lot of hassle to work in there, and you'll be restricting airflow for the burners.
How do you plan to construct the chimney?
Use 16x16 shelves. It needs space to breathe.
You can rewire the control transformer to run the controller on 120V if you want to use the thermocouple. I'd put the thermocouple in a protection tube or it won't last long if you plan to fire in reduction.
You can put the flue opening between the burner ports. Make the flue opening equal to the total area of the burner ports. You can always damper it down.
The bottom shelf will need to be above the burner ports. Have a bag wall for each burner under the shelf. Target bricks can just be a brick leaning against the wall at the end of the firebox, or a brick set upright but turned at an angle to the burners about 2/3 of the way from the burner.
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13 minutes ago, Min said:
It does look like a crawl/reticulated glaze but I think the tricky part would be how they got it to stay on the pot on the undercut vertical surfaces.
100 Grand maybe?
Those are the best! Seriously, I want to eat that pot.
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Luckily there are a ton of online resources to help people do their own kiln maintenance. It's a lot less daunting than before the internet. Most of the kiln manufacturers have good online videos showing how to test, diagnose, and repair kiln issues. It's a good time to be a kiln owner!
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So the metal rod is the stem? First you'll need to decide what size rod you're going to use. Then when you make the flower, make a short hollow stem at the bottom of the flower that the rod will slide into. Make it big enough to allow for shrinkage of the clay. Make the stem a couple inches deep, and thick enough to support the weight of the flower. Then after firing you can glue the rod into the pocket using marine epoxy.
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It's easier to overpower these little round kilns. Sometimes you need to back off the burners to get them to go. Also, what size shelves did you have in the kiln? You usually need to use a smaller shelf than what an electric kiln of that size would use, so there's room for air to flow. A lot of people also put a shelf at the top, like 3 inches below the flue opening. Even a short pipe over the flue will increase the draw. You can even make a small chimney out of stacked soft brick.
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Murphy's will work okay on the wood. The smoother the wood is the better, though, so the plaster doesn't have anything to grip on.
Tapping a bunch works fine. If you were making lots of mold then a vibrating system would be good, but for the occasional one-off you'll be fine.
https://ceramicartsnetwork.org/daily/article/Plaster-Mixing-101-How-to-Mix-Plaster-for-Ceramic-Molds
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14 hours ago, Twitchy said:
I decided to explore the opinion of AI on matters related to this subject, so I asked Google Gemini AI a series of questions.
Interesting stuff. The main thing it's missing is that the sodium is not just reacting with the silica. It also needs alumina in order for it to form the glaze. Pure silica will not be affected by sodium vapor. We used to dust flint onto our salt kiln shelves to protect them.
High zirconia blanket is about 15-17% zircon. It's in there primarily to bump up the heat rating of the blanket. It may help protect from the soda, but not much. High zirconia bricks are 60+% zircon, so it's going to be considerably more durable than the fiber.
The life span of salt and soda kilns depends more on the amount of salt and soda being used in each firing than which one you're using. Salt kilns can outlast soda kilns and vice versa. In general, I see soda people using a lot more material than salt people.
Neither salt nor soda is more dangerous than the other, and your car will create many times more pollution than a salt/soda kiln being fired every week. Much of what comes out the stack is water vapor, and about 96% of the salt/soda that goes into the kiln comes out the stack as the same thing.
Read 'The Truth About Salt' by Gil Stengel in the Sept. 1998 Ceramics Monthly. HERE is some other good info. HERE is a good discussion.
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Looks like it's wired wrong. You've got a wire going from the relay to the element, then jumping to the other end of the element. Each element needs both wires from the relay. So the relay wires should go to one element, then jump to the other element:
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Does the kiln have a safety switch on the lid? If so, it may be out of adjustment.
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I agree regarding the firing schedule. A shorter firing with holds in the proper places could cuts hours off the firing time, and probably reduce firing costs as well. The slow creep to 300F is totally unnecessary, especially if your work is dry. Just run it up to 200F or 220F, hold as long as needed to make sure everything is dry, then go for it. Also, that first ramp can be a lot faster than 60F/hr, like 150F/hr will work just fine. There's no reason to take 2 hours to get to the preheat temp, because the hold is where you're really drying things out.
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If the body bands are tight (check them) then the plywood is unnecessary, and you can definitely tilt the sections to get them through doorways. Just don't grab along the inside lip of the bricks you you could crack the grooves. Use the carrying handles and you'll be fine.
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Fibrecoat sounds very similar to other zircon based coatings. The problem is that fiber shrinks, cracks, etc, and those small cracks will allow for penetration by the soda fumes. You just can't create a complete barrier with the coating. it may last a while if you're religious about re-coating it, but there's a reason everyone uses hard bricks for salt/soda kilns. It's been proven to be the best option.
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Move it in sections, don't try to lift it all at once. Unhook and remove the lid. Stack the sections in the truck, making two stacks if you can. Put foam board underneath each section. The pink house insulation board works well. Set down the wall sections first, with the lid and floor slabs on top (if the floor is a separate piece). Foam board separating everything. Wrap it all up with plastic stretch wrap and secure the load as best you can. I use a cargo tarp and that works really well. If you put straps over the top, put foam board between the straps and the kiln. Don't crank down too tight with straps or you could crack the bricks.
- Piedmont Pottery and Hulk
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That's a cone 05, not 5. That would explain why the cone 5 glazes didn't melt.
- Roberta12, Bill Kielb, Babs and 2 others
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I usually fire my kilns at night so I don't really see what's happening with actual temps in the kiln, but today I started it up in the morning and was in the studio in the evening and got to see exactly what was happening during the cooling cycle. I do a slightly-slow cooling cycle to even out the results in my 3 kilns because they all cool at drastically different rates due to their sizes. I do a drop from the peak down to 2000F, then cool at 175F/hr down to 1500F. This gives me identical results from all 3 of my kilns. This firing I'm talking about here is in my 10 cubic foot L&L EQ2827-3, which has 3 zones, and was packed very tight in the middle. I was surprised at just how much slower the middle cools compared to the top and bottom. This photo shows how it's going part way through the initial drop from peak temp to 2000F:
As you can see, the middle and the top are nowhere close to each other. In a normal firing segment, a 73 degree difference would stop the firing with an error code. So why isn't it doing that here? It's because the cooling rate is set at 9999, or full speed. Any time you use 9999, whether it's climbing or dropping, the controller lets the kiln do its thing and doesn't care if the sections aren't even. Firing up or down at 9999 is the fastest, but you sacrifice evenness. As the temp continues to drop, we see this:
Here you can see that the top section (TC1) has started firing again. The set point for this segment was 2000F, at which point it should start cooling at 175F/hr, yet the top section passed that by about 20 degrees before the relay kicked on and the controller stopped the drop. Why did it let it get so far below the set point? Because it's averaging the 3 zones. Once the average of the 3 zones hits the set point it will start to fire each section again as needed to match the set point.
I get a lot of questions from customers about error codes and cooling cycles. The biggest problem is that the kiln can't always keep up with the programmed cooling rate. There are a number of firing schedules out there on the internet that people are trying that use a rate of 600F/hr or more for the fast drop portion of the cooling cycle, and many kilns simply cannot cool that fast, especially the middle section. When you have a specific rate programmed, the controller will send out an error code if the kiln can't keep up with that rate. So if you want a really fast drop you should use 9999F/hr, not a specific rate. For most people doing slow cooling with cone 6 work it won't matter if the sections are not totally even during the drop. If you do need more precision, like if you're firing crystalline work and it's important that you don't overshoot any target temps, then you'll want to put in a slower drop rate that the kiln can actually keep up with, and the controller will keep the sections even and not overshoot set points.
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They would probably be okay, but any time you shut down a glaze before it's gone through its complete melting cycle there's a chance of something going wrong like crawling. It would also depend totally on the glaze formula as to just how much things would harden up at low temps. I would just carefully wrap them in something soft and pack them so they don't move and rub. If you're using brushing glazes they tend to be pretty durable before firing anyway.
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Does the kiln come apart in sections or is it all one piece? Is the floor joined to the bottom of the kiln?
Kiln conversion
in Equipment Use and Repair
Posted
Bring the burner in along one wall, and have the flue opening centered on the opposite wall. Put a target brick about halfway in.