LOWELL BAKER on wed 31 jan 01
Since so many of you are asking I will send this to the list.
First of all you need a copy of Nils Lou's book "The Art of Firing".
Go to pages 51 and 52 to find the drawings of the sawdust burner.
The most recent modification I have made is to change the primary
air intake. I have changed the tube within the tube system that is
shown on page 52, back to the T with a gate valve as diagramed on
page 51. The tube within a tube simply clogged with sawdust too
easily and lacked precise air control.
I would place the T with a gate valve immediately outside of the
sawdust bin, not some distance away as shown in the diagram on
51. On my current burner it is actually inside the bin with a three
foot riser pipe and the gate valve on top of that pipe, but I plan to
change that to the outside soon. I like the idea of the riser even if
the T is on the outside because you can stand to make minor
adjustments in the mixture.
Finally, I am using 2 inch PVC for the injection pipe rather than the
3.5-4 inch pipe. I would not go to the larger pipe unless I was firing
a kiln in excess of 120 cubic feet.
Do remember to ground the pipe inside and out. This thing can
really blast you with a static charge. To ground the inside, I have
simply screwed dry wall screws through the pipe (only until the
smallest part of the tip penetrates the pipe) and attached the head
end to a wire and then to ground. This is a slight modification from
the published drawing and a lot simpler to build.
The fire box on my second chamber is 12 inches wide X 16 inches
tall X 36 inches long. This is what I call a half Olsen firebox
because it is below the stacking area. The size of the firebox
seems to be perfect for the sawdust burner on a two inch tube.
I believe that I have been feeding too much sawdust into my kilns
for years. The current rate of about 12 cubic feet per hour seems
perfect.
Finally a digital pyrometer is almost essential to help you get the
mixture and feed correct. When it is correctly set the heat goes up
at an astounding rate. You can set the mixture to the rich side to
slow the firing or hold temperature.
I have been using a stoneware body:
Goldart 60
Hawthorne Bond 60
Ball 40
Redart 20
Flint 10
Custer feldspar 10
Kyenite 20
35 mesh grog 10
The body is a little course but I like the way it works. My standard
classroom stoneware drops the Kyenite and grog.
I am getting a warm red brown on the unglazed parts where there is
no ash or the ash is light. This surface looks like a light even dark
salt glaze. The ash is dark green to dark brown. You can expect
a light Noborigama type ash, but if you want anything more this
may not be your burner. In a small kiln you could take the
temperature to cone ten or so, mix fireplace ash with your sawdust
and inject it on your pots then take it to cone 12-14 to melt.
I know you can melt Iron with this burner so don't run it into a
fragile firebox. I would not point it at an IFB wall because the
abrasion of the sawdust will cut through the wall in time. If you
have an IFB firebox use a hard target brick.
One last thing, really; I am sharing this information with you
because I think the burner is a good idea. I would like you to share
your findings, good and bad, with the group.
I have just been given the firing chamber of the new Tatsu Maki
Gama (Tornado Kiln) so I am going to make some pots to really
blast.
W. Lowell Baker
The University of Alabama
dayton j grant on thu 1 feb 01
man your thing sounds bad im in the middle of the city so i dont know
about wood firing that much but it sounds like you have a very efficient
deal worked out there and it really is our responsibility to make the
best use of our natural recources it sounds like your system should and
probably will become widely known and used i hope you are recognised as
the "cat"in the area of modern wood firing ..keep on doin this stuff
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