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2Nd Hand Kiln! Completely No Experience! Help

electric kiln controls

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#1 ToniEve

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Posted 10 December 2013 - 08:42 AM

Hello Everyone,

 

I am just setting up an olympic electric kiln and i understand pyrometric cones, kiln sitter, and stacking, but when it comes to the 2 dials that i need to operate i have no idea, there is no information in the manual referring to these dials.

 

ones is part of the kiln sitter which says 'hours of estimated firing time' fairly self explanatory however, how do i know how long to set it to, i'm planning to fire to cone 06, how long will that be roughly..?

 

The other dial says:  "LO - 2 - 3 - 4 - 5 - 6 - HI"   i'm guessing this is the temp/speed in which it reaching the temperature that the cone will bend at.. but i have no idea really... or how to use it in reference to cone 06...

any advice on this will be very much appreciated!!

 

thanks so much,

Toni

 



#2 jolieo

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Posted 10 December 2013 - 08:51 AM

Hi I too am new, and I too have a second hand kiln, except mine is discontinued , therefore old. I went on to the manufacturer's website and found the manual in PDF. If that hadn't worked , I would have called the manufacturer . They will still help you even if the kiln is not new. After all it is a big investment even for a little one, you will be buying replacement everything if successful , and if very successful you will need a bigger better kiln!:)
So once my kiln is set up I will test run it , noting when cones mature and then I will come here with my 6421 questions and hopefully get sorted out. Jolie

#3 Marcia Selsor

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Posted 10 December 2013 - 08:53 AM

The dial with the hours is a timer. My little kiln takes 6-8 hours to bisque.

For the heating element controls  start on low for 2 hours, then 3 or 4 for 2 hours and high for the rest. The first few times you fire it watch it closely. Put more time on it and use witness cones. Does this kiln have a kiln setter, some supports on the inside to set a cone?

 

Marcia



#4 neilestrick

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Posted 10 December 2013 - 09:21 AM

The timer should be set to approximately 1/2 hour longer than you expect the firing to take. It does not control how long the firing will take to get to temperature. It's a backup to shut the kiln off in case the sitter fails. It simply shuts the kiln off when it reaches zero. So set it to 15 hours for your first firing, and do the math at the end of the firing to see how long it actually took. From then on, fire with the exact same turn-up schedule, and set the timer to 1/2 hour longer than the actual firing time.


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#5 ToniEve

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Posted 10 December 2013 - 11:20 AM

Thanks everyone

yes the kiln has a kiln setter, so i know (providing it woks) that it will shut off when the cone bends. so i see now that i can just add time onto the timer mid firing if i ever had to do that! 
i will  follow your advice and set it to 15 hours, keeping a close eye on it, i will turn it from low to '2' and then up an increment every 2 hours. 
Am i aiming to get it to HI, or should that depend on the type of firing/clay/cone etc?

 

thanks for such speedy responses!

Toni



#6 neilestrick

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Posted 10 December 2013 - 11:33 AM

Assuming everything is dry and not overly thick: 1 hour on low, 1 hour on medium, then high till the cone bends.


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#7 Marcia Selsor

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Posted 10 December 2013 - 01:25 PM

Neil is right. I am use to firing student work. Very cautious.

Marcia



#8 neilestrick

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Posted 10 December 2013 - 06:34 PM

Most kiln sitters are a clockwork mechanism designed to fire more slowly at some parts of the firing and speed-up during other parts of the firing. One critical place they slow down is around 1,100 F as kaolin off-gasses to meta-kaolin.

 

Our old Cress with Bartlett Kiln Sitter was like this. The fast-to-slow-controller controls how fast this clock mechanism is advanced

 

Kiln Sitter is actually the brand name of the shutoff device from the W.P. Dawson company, and has nothing to do with the speed of the firing. The power goes through it, but the switches that control the rate of climb are a separate part. Skutt bought the rights to the Dawson Kiln Sitter a couple of years ago, and now makes them. Orton made their own version called the AutoCone, but I'm not sure if that's still being made.

 

There are numerous other firing controls used by various kiln manufacturers in combination with the Kiln Sitter that control the rate of climb automatically, so you don't have to turn the knobs every hour, but the Sitter itself is simply a shutoff device. The Cress Firemate is a good example.


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#9 Celia UK

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Posted 10 December 2013 - 06:47 PM

I have a small kiln with similar controls and have been struggling for a year to get my glaze firing right. The biggest problem for me was not knowing what heating rate each number on the kiln controller related to - all the firing programs said things like 100oC and hour for X hours then FULL TO max temperature. I didn't know whether 100oC an hour was ON, 1,2,3, or 4. Though I knew it had to be down the lower end! While brush on earthenware glazes were fine with, for example 2 hours on 2 then FULL to 05 minibar in the kiln sitter, I had crazing problems with dipped/poured transparent glaze over and over again. My 40 litre top loader fired in 4-5 hours, which seemed on the quick side, but it had had all replacement elements when I bought it second hand, so I thought it was just super efficient,

Eventually I called in the kiln engineer who thought perhaps the thermostat (controller) had failed, but on testing, this was not the case. I borrowed a digital controller and was able to measure the temperature for each number on my manual kiln controller, as the kiln fired - and hey presto I have discovered that even number 1 on the controller, was firing at more than 100oC an hour. My crazing problem was the result of the kiln firing too fast in the early stages. At last! Problem solved. I've even refired a number of pieces that had crazed, this time going slowly (100oC / hour) to 600oC then full to 1100oC and they are fine.

The other thing that helped me was coming across a Potterycrafts document (online) called Programming your electric kiln, that explained, the firing process in a very straightforward manner, including the importance of the rate of temperature increase through 573oC. It also gave firing schedules for different clays and making techniques. My wheel thrown, white earthenware with dipped / poured glaze needed to be much slower than I had appreciated, and coupled with a 'vigorous' kiln, had caused me great frustration over the year. I don't want to invest in a digital controller for this small kiln as it will cost almost as much as I paid for the kiln itself, but I do now know the manual settings I need in order to get the right firing speed. Good luck with yours, I hope you get it sussed out quicker than I did,

#10 neilestrick

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Posted 10 December 2013 - 08:18 PM

I agree, Norm. If you really want to have control over the process, a digital controller is a must!

 

Celia UK, crazing can be the result of poor glaze/clay fit, or of cooling too fast. Since the glaze isn't even melted at the early stages of the firing, the speed of the temperature increase doesn't really affect the glaze directly. So I'm a bit confused by how going slowly at the beginning has helped with crazing. But my best guess is what is actually happening is that by slowing down the firing, the bricks in your kiln have more time to absorb heat, which then slows down the cooling. John, Norm, anyone else have thoughts on this? What am I missing here?


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#11 Celia UK

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Posted 12 December 2013 - 11:31 AM

I penned quite a lengthy reply to this post last night, but it seems to have 'disappeared'. Can't get all my thoughts back together now, but found previous posts very interesting, thank you!

Thought I'd solved my problem but am wondering if you're right Neil, along with the fact that I brought the kiln into the house to keep an eye on the controller, so the room temperature is much higher than in the garage - which would also slow down the cooling rate. If I set it off in the garage again, this would tell me if this part of the hypothesis is correct. Hubby has decided that a digital controller will solve his Christmas present dilemma - and I'm not about to argue!

#12 ToniEve

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Posted 12 December 2013 - 12:54 PM

Hi everyone!
thanks for all of the advice, i have now started the kiln up for the first time following everyones advice, just one more question, it makes a buzzing noise every 20 seconds that last for about 8 seconds. it this the elements turning on and off...is this how its supposed to work/heat?   or is this a sigh of something bad?  
ive had it on for 2 hours now! 

 



#13 suzannah168

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Posted 13 December 2013 - 12:06 PM

I too have recently bought a small 2nd hand kiln, a Cromarty Little Wonder fitted with a Kiln Sitter, quite old but in good condition.  I've stocked up with mini cones for it but then had no idea how long to fire for and how to ramp it.  Consequently I've just invested in a Stafford Instruments ST222 Controller.  I'm now trying to understand how to program it.  Now reading manual for 3rd time. Slow on the uptake - Me? Just like to make sure I've got it right  :).  Will keep you updated with my progress.   



#14 Chilly

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Posted 14 December 2013 - 05:53 AM

I too have recently bought a small 2nd hand kiln, a Cromarty Little Wonder fitted with a Kiln Sitter, quite old but in good condition.  I've stocked up with mini cones for it but then had no idea how long to fire for and how to ramp it.  Consequently I've just invested in a Stafford Instruments ST222 Controller.  I'm now trying to understand how to program it.  Now reading manual for 3rd time. Slow on the uptake - Me? Just like to make sure I've got it right  :).  Will keep you updated with my progress.   

 

Hi Suzannah

 

I've got the Stafford ST315 and find it really easy to program.  Set up a new program last night to run a slow bisque.  On another thread there was mention of a Potterycrafts document, which I read yesterday, it really helped me understand the reasons for different firings. http://potterycrafts...g_Your_kiln.pdf  Good luck.  I've just looked at the instruction manual, it's similar to mine, so PM me if you want to talk....


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#15 suzannah168

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Posted 14 December 2013 - 08:41 AM

Hi Chilly,

Thank you for the info. I've saved it to my computer and will study it tomorrow.  I'm off to see Military Wives this evening so won't have time today.  I think your Stafford ST315 is the next one up from mine. There is an instruction book but I learn better by being shown so if I have to work it out for myself it will take me longer. I'm not great with tech stuff. So it would be great if I could ask you questions if I have a problem.  Thanks again  :)






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