Sunday, February 26, 2006

Stuff We Did This Weekend

We loaded and fired a bisque kiln on Saturday.

While it was firing, I pulled the elements out of the old kiln that we are converting to a raku kiln. Some of the elements were held in place in channels in the kiln brick with metal pins, about two inches long. I saved the pins off to the side.

After pulling the elements, I started to think about the fire box that we need to build for the kiln. We had purchased an old kiln section, two bricks high, wrapped in sheet metal, from the Daleys a couple of weeks ago. The kiln section is a decagon (ten sided), while the body of the raku kiln is an octagon (eight sided). The kiln section has a larger diameter than the raku kiln.

My plan was to take apart the kiln section, cut the bricks down a bit, rebend the steel sheathing around it, put a four inch round burner port in one side, then reassemble. I thought that, even though it didn't have the same number os sides, that the kiln body and firbox would overlap and work just fine.

My biggest hangup over the whole project is rebending the steel. I finally thought it through far enough, that I could clamp the metal to my workbench with a two by four, then rebend (with my trusty mallet).

I started to disassemble the kiln section. There were a lot of screws that passed through the metal, and then dug into the soft fire bricks a little bit that I removed. There was also bracing bracket made of a heavier gauge metal that wrapped across three sides of the kiln that I struggled to remove. I broke two screwdriver blades trying to turn the screws holding them in place, and and had to use a hacksaw to cut the heads off of two of the screws. I then placed my trusty metal screwdriver (the handle is metal, along with the blade, and half of the handle can fold out for more torque. It was my grandfather's and I think my dad got it from him off an aircraft assembly line), and worked to pop apart metal.

It came apart.

I learned a lot about how the kiln was put together, as flimsy metal sheath flopped open, and all of the kiln brick fell to the cement floor. Many of them broke, or were damaged.

I started salvaging the whole bricks, and stacking them on top of the raku kiln. It was then that I noticed that the brick length was the same as was used in the raku kiln. I ended up being able to salvage almost enough whole bricks to rebuild the firebox as an octagon. I bought a masonry disc for my table saw, and used it to rebevel all of the kiln bricks (plus one extra brick that I had). Some of the bricks had an end broken off, or broke cleanly in half. I used a hammer to drive the kiln elements pins through the bricks, to hold them together. Two badly damaged bricks lined up to where I would bore the hole for the burner, where I could cut most of the damaged brick away.

I made another run to Home Despot, to buy a pair of metal snips. I got the kind designed for cutting a left handed circle. I returned a bunch of copper pipe fittings that Julie had run across during the week, and used the refund to pay for half of the snips.

Returning home, I cut a four inch hole into the sheet metal, and cut a length off the end that represented two sides of the kiln. I stacked all of the kiln brick into an octagon, wrapped the metal around it, and position the hole over my damaged kiln bricks. I used a set of bungee cords to hold the metal in place, then a set of sheet metal screw to hold it permanently together.

I bored a pilot hole through the kiln brick where the burner port was, and threaded the blade of a coping saw through. It took a minute of two for me to cut out and shape the burner port.

The firebox is the same diameter as the kiln body, and the kiln will sit directly on top of it.

The next stage in the project is to cut vent holes into the top and bottom of the raku kiln, a set for the flames to rise out of the firebox into the kiln, and a chimney vent in the lid of the kiln.

I need to build the cinderblock pad out back. This will have a layer of sand on top, with the damaged kiln floor that we got from the Daleys. The fire box sits on top of that, then the kiln tops off the stack.

In a couple of weeks, we will order our burner from Wards Burners, along with two pairs of raku tongs and another set of gloves.

Maybe we can do our first firing before tax day.


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