Help with using a Duncan Automatic Teacher-Plus Kiln

[Nataniajoy24]

Hello folks! I received a Duncan kiln from a family member about 7 years ago and was never taught how to use it. I attempted to figure it out on my own, but gave up because I was having too much trouble with it. I have never operated a kiln on my own- only seen electric kilns in use. 

Has anyone operated this particular kiln (DA820-2), and if so, could you answer a few questions for me?

• I believe I was having trouble because I did not have any pyrometric cone/bar things to turn off the kiln when it reached the right temp (clearly I'm a newbie). In the manual I have for my kiln, it says I need 'ASD' cones.  If my kiln fires to Cone 8, which cone of pyrometric bars do I need ? Does it always depend on the clay's cone?
• Where do I place these ^ cones when I have them? Is there a hole in the bars that slides onto the knob on the inside of the kiln wall?
• Do I need to have witness cones + the ASD cones? 
• After each firing, do I need to have new witness cones? 

Thank you!!

Natania 

 

[neilestrick]

You need small cones or bars, for whatever cone you're firing to. Most folks bisque to cone 04, then you'll glaze to whatever cone your clay matures at. Your clay and glaze should mature at the same temp. In electric kilns, that generally means either cone 04/05 or cone 5/6. To use the cone, lift the weight on the sitter, push down the claw that holds the weight, then place the cone inside the kiln on the two bars in the sitter, with the rod sitting on top of the cone. That rod is connected to the claw on the outside. When the cone bends, the rod goes down, the claw goes up and releases the weight which hits the switch that shuts off the kiln. Have the number on the cone face toward the inside of the kiln, so you can see it. The timer on the sitter should be set to about 20 minutes longer than the firing is expected to take. It is just a countdown timer, it does not control how long the firing takes. So you'll need to do a bisque and glaze firing to figure out how long the firing will take and set the time accordingly. For the first firing just set it to 12 hours and do the math afterwards. You need a new cone for every firing. Witness cones are not necessary once you have the sitter calibrated. You may want to use them for the first couple of firings to make sure everything is good.

[Nataniajoy24]

Okay, thank you! Do I need to warm up the kiln before using it or do I load it and do the process you explained and then prop open the lid after the kiln shuts off? On some older kilns, I’ve found (from YouTube videos) that the people slightly prop open the kiln and set it on low for several hours with the peepholes open. Any advice for this part? 

[neilestrick]

If the kiln doesn't have a downdraft vent attached, keep the top peep open throughout the firing. You really don't need to prop the lid. Make sure everything is dry before firing. No need to warm up the kiln before loading. Keep the lid closed after firing until it's cooled down below 250F.

If you have a teacher that would let you help load and fire his/her kiln a couple times that would be good.

[yappystudent]

8 hours ago, Nataniajoy24 said:

pyrometric cone/bar things to turn off the kiln when it reached the right temp (clearly I'm a newbie). In the manual I have for my kiln, it says I need 'ASD' cones.

basically what you do is buy cones for different temps you might be firing to, and see which ones are melting while looking through the vent holes of your kiln. You'll need something to look through like welding glass or special glasses or you'll burn your retinas. If your kiln says cone 8 (mine does) it probably means it will technically fire around cone 8 but you'll get a lot more life out of the elements if you keep it around cone 6. Mine says cone 8-10 but since there are a ton of beautiful glazes and clays for 5-6 that's what I'm going with, and I'll save some money in the long run. Don't prop your kiln open just leave a kiln plug out through the whole firing like Neil said. 

8 hours ago, Nataniajoy24 said:

Where do I place these ^ cones when I have them? Is there a hole in the bars that slides onto the knob on the inside of the kiln wall?

just to be clear the cone does not shut off the mechanism, you'll just be checking it through a kiln plug hole and when the one that's the temp you want has melted, then the kiln has reached the temp you want it to get to. Place the cones where they can be seen thusly. To be honest I'm new to kilns and I don't know what your kiln means by "Automatic" since it looks like a manual kiln from the images. This means you have to watch the temperature and turn it off yourself. There is a thing called a "setter" involved in the process but someone else will have to pick up the thread because I don't know from manual kilns. I wouldn't fire it until you figure out how to shut it off. 

[Fred Sweet]

Do you have the manual for your kiln? The link below is for the manual Duncan kilns (includes yours) from the Paragon kiln company, who were providing parts and service after Duncan was disbanded.

https://www.paragonweb.com/files/manuals/LX_914_Duncan_Kiln_Owners_Manual.pdf


Regards,

Fred

[oldlady]

nataniajoy,  you are very fortunate to have such a nice manual kiln as a gift.  i thought by now you would have received an answer that addresses your problem as a totally new kiln user.

couple of things might help you understand the manual fred has so helpfully found for you.  you need to realize that the kiln is a very old one as far as its manufacturing date is concerned and there was a slightly different vocabulary used then.  "Automatic"  back then meant your kiln was equipped with a Kiln Sitter that would mechanically turn off the kiln when a particular temperature was reached.  the manual keeps referring to it as the ASD, automatic shutoff device (or sitter. prior to the use of a sitter, the potter had to watch the firing and turn it off at the end by looking into the kiln peep holes and judging the temperature at which to turn off the electricity. ) cones have been use for over a hundred years to help do that.

the temperature you select for each firing is commonly referred to by a cone number.   that means the same kiln can be used by potters who fire earthenware or stoneware which is usually fired to a higher temperature.  so you need to select the cone number for the clay and/or glazes you are using.

the number on the cone indicates a temperature but the firing can take a little longer as the elements wear out over time.  so the cone ,which you place HORIZONTALLY across the two little arms, will determine the time and temperature of your firing.  the arms hold up the cone and the rod end of the "claw" of the sitter sits over the cone resting on it.   SINCE THE INVENTION OF CONE BARS MANY PEOPLE USE THEM IN THE SITTER.  bars are of a uniform size end to end.  cones are tapered and some people have trouble putting them onto the arms and getting the claw rod in the middle of the cone.

when the cone gets hot enough for a long enough time, it will melt.  that means it sinks down and allows the rod end of the claw to sink as well.  the other end of the claw, the part outside the kiln, is really the claw looking end and it is holding a weight that will be released by the rising of the claw.  the weight will snap down and activate a round electrical shut off button that is located on the outside of the sitter.   (if you find you cannot start your kiln at any time, check that the claw is holding the weight and the button is close to the kiln, not sticking out.) 

i hope this is enough to help you read the manual and that will explain your particular kiln.  

the most important thing you need to learn is that it is CRITICALLY IMPORTANT that you understand the cone numbers of your clay and glazes.  look at a CONE CHART and read the numbers and the temperatures carefully.   there are some essential facts that are commonly glossed over when experienced potters are talking to each other.   

09 08 07 06 05 04 03 02 01 AND THEN CONE 1 2 3 4 5 6 7 8 9 10 ETC.  are each a little hotter running from left to right.  check the chart!  and check your clay.  write the cone # on the bag of clay so you  DO NOT make the mistake of thinking that cone 6 is the same as cone 06.  that is a completely different temperature and if you use cone 06 clay and use a #6 cone in your sitter, you will probably melt everything and ruin the kiln.

see the recent post by benzine for what can happen.

hope you bothered to read this long post and understand it.

 

 

[Jcots]

I have the exact kiln...I’m use to my old kiln which had three dials high med and low...I’m not sure how to use these dials...do I turn them clock wise...? Will they switch on their own...? How do I do a bisque cone 04 and what do I do with the dials for a cone 6 glaze...? Also at the bottom what’s that switch. For...thx in advance for any advice

[neilestrick]

2 minutes ago, Jcots said:

I have the exact kiln...I’m use to my old kiln which had three dials high med and low...I’m not sure how to use these dials...do I turn them clock wise...? Will they switch on their own...? How do I do a bisque cone 04 and what do I do with the dials for a cone 6 glaze...? Also at the bottom what’s that switch. For...thx in advance for any advice

Paragon Kilns serviced these kilns for years. They should be ale to give you instructions and/or a a manual.

[Wcrowe]

Another newbie here!!  I am getting ready to buy a Duncan automatic teachers plus model LT-3K kiln. The people bought it brand new a few years back, the got it all set up but then unfortunately she had a stroke and had never used it. I am getting my garage wired for it... 220..... but looking for a spot for it, but I don’t know the dimensions. Does anyone know how tall this model is??

[Min]

17 minutes ago, Wcrowe said:

Another newbie here!!  I am getting ready to buy a Duncan automatic teachers plus model LT-3K kiln.

Hi Wcrowe and welcome to the forum!

Lt-3K will be the model of the kiln sitter on the kiln, not of the kiln itself. Manuals for Duncan kilns about 1/3 the way down this from Paragon, it should have the height info in the manual. The kiln will have a faceplate on it with the kiln model number etc, you can see the model numbers in the link.

[Bloomfield Pottery]

Do I have to use the timer-dial with this kiln?  I put it on 13 hours, with a cone 6 cone placed in the automatic shut-off mechanism, and it never reached temperature after 13 hours.  I'm firing it again with the dial set to 20 hours.  that seems excessive for a cone 6 firing.  Any thoughts?

Also, is it possible for a new kiln to NOT go up to cone 6?  it had never been used, and I followed all directions for first (clear) firing, etc....  

Edited August 29, 2019 by Bloomfield Pottery
add another thought

[Bill Kielb]

@Bloomfield Pottery

Yes,

That is quite high time wise. Have you downloaded the manual above and  set your switches appropriately? If yes, then you may need to check your elements. Elements wear and as they wear firings will take longer as their resistance increases their output decreases. Elements that wear or increase in resistance by 10% generally should be replaced as they usually have difficulty achieving high fire temperatures. This is especially true for cone 8 kilns more so than cone ten kiln firing at cone 6  as they simply have less power available.

your kiln. Is 240v, 24 amps so new, the combined resistance of all your elements will be 10 ohms. Once this combined resistance goes up by 10% or to 11 ohms its likely time to change them as making cone six with full power applied begins to take super long or cannot be achieved..

A normal fast glaze often takes about six hours and a slow glaze say 7 to 9 hours but this can vary from kiln to kiln.

Edited August 29, 2019 by Bill Kielb

[Hulk]

Hi Bloomfield!

Curious, are you placing cone packs on each shelf? ...makes each firing a bit more expensive, however, you'll get clear indication of heat work achieved at each level. I see some variance between levels, and the cone in my sitter gives way a bit early. I'm watching the cone packs through the peeps (with appropriate eye protection) for the final shut down.

I'm also using a pyrometer for real time feedback, helpful for slowing down through the critical temperature ranges, and managing the initial cool down/hold - also helpful for note taking - repeatability is science!

I'm mitigating heat work variance by adjusting the load on each level - sizes, weight, density - and staggering half shelves. My kiln came with a full set of brand new half shelves! Initially I found half shelves to be a pia! ...now I love'm, as I'm getting much more even heat, and firing more pieces in each load (pieces with wide rims - bowls - at the edges of staggered shelves).

[Crystal McCann]

On 8/7/2018 at 8:50 AM, neilestrick said:

You need small cones or bars, for whatever cone you're firing to. Most folks bisque to cone 04, then you'll glaze to whatever cone your clay matures at. Your clay and glaze should mature at the same temp. In electric kilns, that generally means either cone 04/05 or cone 5/6. To use the cone, lift the weight on the sitter, push down the claw that holds the weight, then place the cone inside the kiln on the two bars in the sitter, with the rod sitting on top of the cone. That rod is connected to the claw on the outside. When the cone bends, the rod goes down, the claw goes up and releases the weight which hits the switch that shuts off the kiln. Have the number on the cone face toward the inside of the kiln, so you can see it. The timer on the sitter should be set to about 20 minutes longer than the firing is expected to take. It is just a countdown timer, it does not control how long the firing takes. So you'll need to do a bisque and glaze firing to figure out how long the firing will take and set the time accordingly. For the first firing just set it to 12 hours and do the math afterwards. You need a new cone for every firing. Witness cones are not necessary once you have the sitter calibrated. You may want to use them for the first couple of firings to make sure everything is good.

I have the same Kiln,  I need to know what type of Element for replacement.  My kiln is not firing at the correct heat.  Suspect element is out.  any help?

[Crystal McCann]

When I use the Witness cones they are not bending at all

 

[neilestrick]

34 minutes ago, Crystal McCann said:

When I use the Witness cones they are not bending at all

 

If all the elements glow when the kiln is on high, but it won't get to temp, then you need new elements. Turn it on high and carefully crack the lid and peek in to see if they're all working. If they are,  you can call Paragon and see if they still have any elements in stock. Also call Euclids.com and they should be able to help you.

[StudioJoKo]

I might have missed this in one of the previous responses,  but has anyone addressed the 3-way toggle switch at the bottom of the control box?  It reads Manual Low, Manual Hi, and Automatic.  What's the difference between Manual Low and Manual High?  Do they affect the performance of the infinite switch?  Am I correct to assume that "Automatic" gradually increases the rate at which the heat switch cycles on and off?  I can't find anything mentioned about that 3-way switch in any of the manuals available on Paragons website.  

[neilestrick]

15 minutes ago, StudioJoKo said:

I might have missed this in one of the previous responses,  but has anyone addressed the 3-way toggle switch at the bottom of the control box?  It reads Manual Low, Manual Hi, and Automatic.  What's the difference between Manual Low and Manual High?  Do they affect the performance of the infinite switch?  Am I correct to assume that "Automatic" gradually increases the rate at which the heat switch cycles on and off?  I can't find anything mentioned about that 3-way switch in any of the manuals available on Paragons website.  

https://www.paragonweb.com/files/manuals/LX_914_Duncan_Kiln_Owners_Manual.pdf

[StudioJoKo]

Thank you for the prompt response Neil.  That's the instruction manual Fred Sweet posted earlier.  I've run though that manual up and down numerous times already.   I've also read pages 8, 9 and 10 thoroughly, and I don't see anything mentioned about the 3-Way toggle switch.  Am I too impatient or need to have my eyes checked?  lol.  The switch is (kinda) shown on the manuals cover image, so you'd think they'd definitely mention it switch somewhere.  But I swear it's not in there.  What does that switch do exactly?

[Fred Sweet]

Start on page 21.

Regards,

Fred

[StudioJoKo]

Well there you have it.  My eyes need to be checked and I'm too impatient.  Thank you!

[K S]

I really like my Duncan Teacher Plus.  Question: For bisque and glaze firing, I start the switch at the 10:00 position, even though no markings are there. I turn the switch to 8:00 position two hours later, 6:00 position two hours later, etc. I keep the toggle at Low Manual. My witness cones from the top, middle and bottom shelves are all the same. Sometimes I do a drop hold on a glaze firing to heal pinholes. Do any of you have a better firing schedule?

[John S]

Hello everyone,

A newbie here! For decal on ceramic,  how much is the right amount of heat/ amount of time necessary? I use a Dowson kiln with infinite switcher. Thanks!

John

[neilestrick]

1 hour ago, John S said:

Hello everyone,

A newbie here! For decal on ceramic,  how much is the right amount of heat/ amount of time necessary? I use a Dowson kiln with infinite switcher. Thanks!

John

It depends on the firing temp of the decals. Find out what cone they go to. You can fire decals pretty fast, as long as the pots themselves can handle the speed.