Wednesday, 13 January 2010

Is this the curse of 2010? Kiln maintenance for complete ameteur technophobes part 2... and 3

I replaced the naughty element yesterday when the replacement part finally arrived. It was tricky, but I felt a huge sense of satisfaction when I tested it with a repeat of last week's paper test and all four elements were getting hot again. So I merrily filled my kiln, switched it on and waited. It seemed to be going well, the temperature was rising as expected, and after a number of hours, it had got up to 850 degrees C. All was going as expected. At the end of the expected firing time, I again went to check on the temperature... Error 1. Boooooooooooooo!!!!
The temperature had fallen to 590 degrees, and the cycle had not finished. I went to bed, and left it to cool down. I was not a happy bunny.
This morning, I emptied the kiln out, and repeated the paper test. I am happy to report that the element I replaced was still working fine. Hooray! At least I had done that part correctly. Which was just as well, as the culprit, clearly visible was one of the lower elements on the other circuits. Unbelievably, that had blown on the very next firing. Thankfully I had ordered a spare element the other day, so could change that one today.
For anyone who's interested in how it is done, (or in case I have to do it again in a few months and have forgotten) here in a nutshell is how to replace a kiln element...

1. Visually identify faulty part. Basically, which one has a break in it? That is the one. Try the paper test in my last post if you ned help narrowing it down.
2. Remove it. This is done by snipping the wire of the element close to the brickwork inside the kiln, and straightening it out. Then open up the kiln controller. This is done by removing the metal controller housing by unscrewing it and resting it on something. I used a box underneath, and a spare piece of wire to hold it in the position I wanted by attaching it to a handle on the side of the kiln. You have to do this, because the other wires coming off the kiln to the controller are not very long, and you can't rest it on the floor as they won't reach.
Then you can see where the element wires join the metal bolts and connect with the current carrying wires.
OK, here's a pic of the element wires (twisted silver colour) joining the bolt part. It makes a connection where it twists around the bolt, and is clamped in place with the blue and brown current-carrying wires by the nuts which are tightened. It then goes through the white ceramic plate that you can see here, through the metal body of the kiln, through a little hole in the brickwork, and then it turns into the coiled springy looking element that you see in my last post inside the kiln.
At this point I had already removed a little silver disk and a nut. I would definitely recommend taking a photo to make sure that you don't do that thing small boys do with bikes sometimes... I figured I needed a photograph as insurance should I get confused about what went where. I removed each part and laid them out in a row in order, so I was sure which order to put them back in. I left a large gap in my row where a wire like the blue one went in the order. I then wriggled the element wire off the bolt, and fed it through the hole in the brickwork, pulling it out from the outside.
3. Fit the new element. Firstly I put it into position in the groove inside the kiln, and fed the long twisted wire tail through to the bolt area pictured above. It was then a simple matter of twisting it around the bolt, snipping off the excess wire, and screwing it all back together.
4. Last but not least, inside the kiln, make sure that the springy bit is well pushed into the grooves and is in the right place BEFORE the first time you fire it. When you fire it for the first time, the elements will be set into that position forever.

So for the second time this week, I have replaced an element and done the paper test... They all work. It is loaded and ready to be fired in the morning... Again. Thanks again to Jonathan for the technical advice, and also to good old Dad who also had some tips. Wish me luck; if it doesn't work I'm going to apply for a job at asda.

No comments: