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Old 03-12-2021, 09:45 AM
Cathy Vance Cathy Vance is offline
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L&L kilns for glass crucible

I use a modified ceramic kiln to melt glass in an 80lb crucible. Getting tired of finding elements sagging out of the brick during changes. The L&L kiln company has a unique ceramic element holder that fits into a soft brick groove. I'm considering going this direction on my next element change. I have no experience with the durability of "kiln furniture" within a glass melting chamber. I'll be testing it by throwing some posts in the chamber with my last set of the old elements. Wondering if anyone has already tried this and if the ceramic parts were up to the task. They are pricey so I would like to avoid a predictable failure.
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Old 03-12-2021, 11:06 AM
Charles Friedman Charles Friedman is offline
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I looked at there web site. The element support furniture, looks very good. And with the quad system, will help in getting too temp. You do have to remember, it is a pottery kiln, designed to go up and down, not so much at holding at high temp for such a long period of time. Having the controls attached to the side, is not good. How long do you keep it hot for? How is the recovery time, after each gather?
If you are just using the element furniture for your existing unit, then go for it. They look good. A lot of routing-out of the old brick, will be fun.
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Last edited by Charles Friedman; 03-12-2021 at 11:12 AM.
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Old 03-12-2021, 11:28 AM
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Pete VanderLaan Pete VanderLaan is offline
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In the past, I got alumina rods from coorstek in Golden colorado and they go inside the elements. It takes a good deal of commitment to cut the rods to the right length and account for the octagonal bends in them but it's well worth it.

Elements flop over in my estimation from two conditions, first, they're simply run too hot and too long which some of the kiln makers encourage you to do because they want to sell you kilns that as Charles points out, were designed for intermittent use firing pottery.

I tend to think that the gauge of the element has a good deal to do with element flop as well. Heavier gauges seem to stand up better. I see 13 gauge wire used a lot in these things. 12 and 10 gauge would stand up better but are more difficult to install. Not running at unacceptably high temperatures would really help as well. Ideally building one's own kiln would be best where the groove and gauge can be dealt with. Something else I've done with those things is to mortar a little keeper over the groove at several points along each section of the octagonal section.

Charles is also on the money about the placement of the controls. The kilns are really simply an effort to sell a bisque kiln just by throwing a controller on the side. and declaring it a glass furnace . I preferred the JenKen as the best of a bad lot, at least in terms of insulation but I have to admit not having spent much time on considering the things at all.
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Old 03-12-2021, 02:27 PM
Cathy Vance Cathy Vance is offline
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Thank you for the analysis and recommendations. My setup is custom with a Watlow SCR and Omega controller housed in an enclosure on the wall. The elements are 11 gauge which Duralite suggested they could coil to fit snug into an old kiln brick groove. The length came out very close but they do require a bit of stretch which is not easy. My intention would be to buy the bricks and element holders of the L&L 10-sided kiln to add to my original housing which contains another 6"-8" of fiber insulation around the crucible chamber. It has two gasket-like access lids made of 3" kastolite and the door is a 6" thick piece of kastolite.
I have run it continuously for weeks and with more time to devote to my glass will start keeping it on for months long stretches. I use SP87 and it holds heat well albeit with a noticeable drop in workability at the end of a 6 hour shift. I like the idea of adding some mortar to keep the elements at bay. I was planning to use a lot more staples this time.
Another aspect of the L&L kiln design I like is the use of single row elements rather than the need for a terminal X brick and going around 2x. I have an old Duncan kiln bought for next to nothing just for the bricks and stainless hardware that was designed the same way. It will require a redesign of the elements to switch to this style but I like the simplicity of a single wrap.
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Old 03-12-2021, 02:38 PM
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rod from coorstek would certainly help and it sounds like a reasonably carefully considered design but it still is what it is. those rods take a while to get and the last time I was at their website, it was difficult.
Given that you're melting SP87, I have to assume you are at least at 2250F. Mark would be the person of choice to make the elements. L and L is not a company I'm familiar with. I did note Charles mentioning digging out the grooves which is no fun on a fired brick. A router sacrificed for the cause might be in order.

Antigua? Who knew?
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Old 03-12-2021, 04:10 PM
Steven O'Day Steven O'Day is offline
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We have been using an LL Kiln for about ten years in the ceramic shop. Works well, much better than the groove in soft brick. If the element holders get banged they can come loose from the channel in the soft brick but the actual holders stand up to a lot of abuse. They look like the same material that kiln furniture is made from.

The other thing I like about the LL Kilns is the zone control, each element has a thermocouple and relay so it can be controlled separately. This keeps the kiln at an even temperature top to bottom.
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Old 03-12-2021, 06:14 PM
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Actual design! What a concept!

https://www.sheffield-pottery.com/L-...SABEgKNaPD_BwE
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Old 03-13-2021, 08:05 AM
Steven O'Day Steven O'Day is offline
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LL Kilns makes a lot of different kilns for industrial and 'hobby' applications. While they are helpful at the factory for service and parts, I would recommend getting in touch with Robert Battey at http://www.nwkilns.com, he specializes in LL kilns.
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Old 03-13-2021, 12:15 PM
Charles Friedman Charles Friedman is offline
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element tabs

Here is a quick and easy element keeper.
Attached Images
File Type: jpg element tabs.jpg (13.3 KB, 33 views)
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Old 03-13-2021, 01:33 PM
Cathy Vance Cathy Vance is offline
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Thank you for the input. Charles, the style of your diagram looks right out of the Henry Halem books. Was that tidbit in Glass Notes? I don't recall seeing it. A nice method to keep the mortar from seeping onto the element. Have you considered a removal process for these dams when the time comes to change them? I would probably use a diamond cutoff wheel unless I'm missing an easier option.
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Old 03-13-2021, 01:47 PM
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I used to just use a ton of element pins. Works well, but chews your bricks up after time.
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Old 03-13-2021, 02:29 PM
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Quote:
Originally Posted by Cathy Vance View Post
Thank you for the input. Charles, the style of your diagram looks right out of the Henry Halem books. Was that tidbit in Glass Notes? I don't recall seeing it. A nice method to keep the mortar from seeping onto the element. Have you considered a removal process for these dams when the time comes to change them? I would probably use a diamond cutoff wheel unless I'm missing an easier option.
**
It should just pop off.
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Old 03-13-2021, 06:32 PM
Charles Friedman Charles Friedman is offline
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Been doing that for years, before glass notes. Old pottery trick. I think i got it from Carlton Ball. He used to turn it on and let it just burn off.
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Last edited by Charles Friedman; 03-13-2021 at 06:36 PM.
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Old 03-14-2021, 02:49 PM
Sean Jones Sean Jones is offline
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Since I installed an SCR (Din-a-mite) my elementals donít move at all.
They now sit in quite shallow, open grooves where they can radiate freely. Hopefully this minimises the temperature they need to run at.
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Old 03-14-2021, 06:07 PM
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Cathy did indicate that her kiln has an SCR. It would be helpful in diminishing the lie down problem but it is not the only issue.
She is melting a batch glass for prolonged times, a rather different issue.
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Old 03-14-2021, 06:22 PM
Michael Ahlefeldt-Laurvig Michael Ahlefeldt-Laurvig is online now
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I dont know Cathy, but if you are serious about glass ,get a real furnace, there are probably about 5000 for sale now, worldwide. Id give you mine, but its difficult to run
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Old 03-15-2021, 07:36 AM
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If it's gas Michael, this is in the caribbean and gas is unaffordable. Hugh Jenkins on the big island of Hawaii pays about $5.50 USD per gallon for propane. I'm not clear about what Franklin does.
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Old 03-16-2021, 10:37 AM
Cecil McKenzie Cecil McKenzie is offline
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i have a small Denver furnace with circular gallery for the elements. I have used old knob and tube insulators cut in 1 inch pieces to put inside the elements and it has helped a lot with collapsing elements. using appropriate seized mullite pieces might work even better. i also have the program set to take an hour to return to temp after adding more cullet.
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