search  current discussion  categories  kilns & firing - misc 

questions about mft kiln

updated fri 2 jun 06

 

Linda T Ferzoco on thu 1 jun 06


I've just been looking at a ton of photos of MFT kiln
construction on Nils Lou's site and have some
questions.

What is the wedge in the car floor accomplish?

I am surprised that the burner ports are in such
proximity to the flue opening. Doesn't that make for
an uneven heating of the kiln interior?

Mind you, I won't need to build one to make bonsai
pots, but inquiring minds want to know.

Cheers, Linda Ferzoco
Pacifica, California

Hank Murrow on thu 1 jun 06


On Jun 1, 2006, at 5:38 AM, Linda T Ferzoco wrote:

> I've just been looking at a ton of photos of MFT kiln
> construction on Nils Lou's site and have some
> questions.
>
> What is the wedge in the car floor accomplish?

dear Linda;

Makes the car fit real tight when it is closed. No scraping of brick
while opening too.
>
> I am surprised that the burner ports are in such
> proximity to the flue opening. Doesn't that make for
> an uneven heating of the kiln interior?

The flame gets across the floor and up the other side before wrapping
around the roof and out the chimney. Works pretty well in the examples
I have seen.

Cheers, Hank
www.murrow.biz/hank

Jennifer Boyer on thu 1 jun 06


To add to what Mel said:

My kiln is a 43 +/- cu ft modified MFT type kiln. I put an arch on
it. Who wants to be gypped out of building an arch?? That's the fun
part!. Also I didn't use Nils's flue design, since I don't reduce. I
have a 42 sq in flue opening in the kiln wall and a fairly standard
chimney design with a culvert. And I used Nils's car design. But hung
my fiber door from barn door rollers on my rafters rather than
attaching it to the car.

The traditional shape of a car is straight sided: same width at front
and back: imagine closing one like that: if it's a tight fit the
bricks are going to grate on each other and possibly bind as you
close the kiln if the bricks are just a bit out of line. In a MFT the
back of the car is wider than the front. The kiln floor is tapered to
match that shape. So the car and kiln floor really don't touch each
other til the car is finally closed. Then they meet for a nice tight
seal. I have stuff under my car that has blown in there: tree leaves,
a few packing peanuts. It's totally cool under the car.

The MFT isn't the only kiln plan with rear mounted burners. The flame
path is sort of a big circle. The flames go forward and up and then
back to the flue. You have less of an issue of trying to protect pots
from a direct hit from the burners. My last kiln design (before my
modified MFT) was one with 4 burners pointing in from the sides. You
always needed a bagwall and if the kiln wanted to be tuned for
evenness with a low bagwall, some lower pots would get hit pretty
hard by the burner flames. I've eliminated bagwalls altogether with
rear mounted burners.

I tune it with a slanted brick at the front of the flame path towards
the front of the kiln. I also place some bricks in the flame path to
create flame turbulence which evens out the kiln. I have to admit
it's not the evenest firing kiln in the world since it really does
better when I reduce. I think the kiln in reduction has longer lazier
flame that evens things out. But it's good enough. Maybe about a cone
difference top to bottom. But my glazes handle that just fine.


On Jun 1, 2006, at 8:38 AM, Linda T Ferzoco wrote:

> I've just been looking at a ton of photos of MFT kiln
> construction on Nils Lou's site and have some
> questions.
>
> What is the wedge in the car floor accomplish?
>
> I am surprised that the burner ports are in such
> proximity to the flue opening. Doesn't that make for
> an uneven heating of the kiln interior?
>
> Mind you, I won't need to build one to make bonsai
> pots, but inquiring minds want to know.
>
> Cheers, Linda Ferzoco
> Pacifica, California
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.

*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************