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Weird Cones From Elec Firing- Update

ran another identical kiln lo

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#1 clay lover

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Posted 10 December 2013 - 09:15 PM

I needed to finish the elementary kids Christmas ornaments, so ran another identical load. Same posts, shelves and ware. Same firing schedule.
Last time, the cone at the thermocouple shelf was solid ^6, the bottom cone was just barely a ^5. almost 2 cones difference. Neil says I might need new elements and relays.
Todays load, same everything, even cone 6 all the way through. WHAT DOES THIS MEAN I should do now????
What could make the bottom of the kiln fire 2 cones cool 1 firing and 3 days later fire a correct ^6 ??
All advice appreciated.

#2 JustPeachy

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Posted 10 December 2013 - 09:22 PM

I don't know diddly about kilns but I do know that some electronics die a slow death, meaning something screwy one day and the next time all is well....the next time, screwy again. Maybe you should just go ahead and replace your elements. The other option is tolerating under-firing on off days until it dies completely resulting in more work in the long run.



#3 clay lover

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Posted 10 December 2013 - 09:27 PM

I am happy to replace whatever, I want to be sure that what I'm replacing is what really needs replacing.
I am electrically challenged.....

#4 neilestrick

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Posted 10 December 2013 - 10:06 PM

Could be a sticky relay. This is a hard one to diagnose without getting my hands on it.


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#5 clay lover

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Posted 10 December 2013 - 11:23 PM

I don't have access to a kiln repair man, what is my next step?

#6 clay lover

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Posted 11 December 2013 - 08:57 AM

Norm, I said the bottom elements were red, doesn't that mean they were working at that time? And they were certainly working when the cone bent to ^6. It seems that something is working sometime, not working others.
The ware was flat Christmas ornaments, same as before, with 4" posts, same as always.

My whiz-bang IS a Bartlett.

#7 Chris Throws Pots

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Posted 11 December 2013 - 10:05 AM

Knowing that all of your elements are getting hot, I'd start by testing your relays. Do you have a multimeter? You'll also need some wire and a 9V battery... or you can just use your car's battery. Shut down the breaker and remove the relays from the kiln, marking each one's position.

 

Start by measuring the resistance (multimeter set to ohms) and confirm with the kiln company that the relay's resitance is in the right range. Next hook up the relay to the battery. Connect the negative side first so as to ground the charge. Then connect the wire to the positive contact point on the battery. Lastly, touch the free end of the positive wire to the positive contact point on the relay. Does it click? When you break the circuit does it click again? Do it a few times. Is it consistent? This will tell you whether you have a sticky or stuck/broken relay.

 

If everything reads properly, then you may have element issues, though from my experience those don't come back to life. When they're broken they're broken.

 

Good luck!


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#8 neilestrick

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Posted 11 December 2013 - 10:14 AM

With a multi-meter you can see if the relays are working. Open the control panel, turn the kiln on High (rate of 9999) and check the power coming out of the relays. Turn the kiln off, back on, and test again. Do this about a half dozen times to see if you can get a relay to stick again. It's the only way to test for sticky relays. The other option is to go ahead and replace all the relays. If they are several years old, they're probably due anyway. HERE.


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#9 Wyndham

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Posted 11 December 2013 - 11:47 AM

From a cold start, relays can work fine,but after some hours it may fail. Easiest and in the long run cheapest is to replay all the relays. Relays take more electrical abuse than elements and seem to fail  more often with older elements, just my experience.

Wyndham



#10 clay lover

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Posted 11 December 2013 - 05:15 PM

THANK YOU ALL.
A direction to go in and some directions on how to get there. exactly what I needed. Much appreciated.

#11 mregecko

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Posted 11 December 2013 - 11:27 PM

I don't believe anyone has addressed the issue that immediately springs to my mind.....

 

How are you loading these kilns, with regards to shelf placement?

 

You said that the bottom of the kiln is a full 1.5-2 cones lower... This has absolutely been my experience if you place shelves close together at the bottom of the kiln.

 

This may not be the case for you, but I just hadn't seen anyone propose that as a cause yet.

 

Since (on an elementary level), heat rises, the bottom of the kiln will tend to be cooler. You can mitigate this by creating larger "chambers" at the bottom of the kiln throughout which heat can circulate.

 

But if you have a few 4" layers of plates/flat ornaments at the bottom, with tall objects on top, the top of the kiln will absolutely fire 2 cones hotter.

 

-- M






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