David Hendley on mon 4 dec 00
I hesitate giving advice because all I have to go on is
personal experience, or jinxing myself, but.....
I have been using cracked silicon carbide kiln shelves
for decades. Can't remember the last time one broke,
probably in the 1980's.
These shelves are REALLY cracked. Some in two different
places on the same long side, halfway across, some
on BOTH sides of the long dimension. ALL of them
are cracked at least a few inches on both of the
short dimension sides.
These shelves are NEVER flipped, since they are heavily
coated on one side for use in my wood kiln.
About 1/2 are still flat, 1/4 have sagged down a bit, and,
believe it or not, 1/4 of them bow upwards!
There is one primo important rule to remember when
stacking a kiln: Line up the shelf supports directly
above the one below. One straight line from bottom to top.
Even if a shelf breaks, it won't do too much damage.
If it's on the top, the 2 pieces will simply come to rest on
a couple of pieces on the shelf below.
If a lower shelf breaks, the weight of the rest of the stack,
as well as the pieces below, will actually help to hold the
broken pieces in place.
The bottom shelf is the most important, because there's
nothing below to support it. That's where I put the handful
of new shelves I have.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
Barb Jensen on tue 5 dec 00
I always post the cracked shelves opposite the cracks; I think the weight of
the posts (if aligned) & shelves above the cracked shelf will keep the
cracked shelf from falling even if it breaks further, as long as the post
isn't right on the crack.
Works for me so far (25 years).
Barb
Edouard Bastarache on tue 5 dec 00
Allo David,
excellent piece of information drawn from years of experience.
Do you use extra posts under the most important cracks?
Please discuss this issue.
Later,
Edouard Bastarache
Irr=E9ductible Qu=E9becois
Sorel-Tracy
Dans / In "La Belle Province"
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
-----Message d'origine-----
De : David Hendley
=C0 : CLAYART@LSV.CERAMICS.ORG
Date : 5 d=E9cembre, 2000 06:25
Objet : cracked kiln shelves; one man's experiences
>I hesitate giving advice because all I have to go on is
>personal experience, or jinxing myself, but.....
>
>I have been using cracked silicon carbide kiln shelves
>for decades. Can't remember the last time one broke,
>probably in the 1980's.
>These shelves are REALLY cracked. Some in two different
>places on the same long side, halfway across, some
>on BOTH sides of the long dimension. ALL of them
>are cracked at least a few inches on both of the
>short dimension sides.
>These shelves are NEVER flipped, since they are heavily
>coated on one side for use in my wood kiln.
>About 1/2 are still flat, 1/4 have sagged down a bit, and,
>believe it or not, 1/4 of them bow upwards!
>
>There is one primo important rule to remember when
>stacking a kiln: Line up the shelf supports directly
>above the one below. One straight line from bottom to top.
>Even if a shelf breaks, it won't do too much damage.
>If it's on the top, the 2 pieces will simply come to rest on
>a couple of pieces on the shelf below.
>If a lower shelf breaks, the weight of the rest of the stack,
>as well as the pieces below, will actually help to hold the
>broken pieces in place.
>The bottom shelf is the most important, because there's
>nothing below to support it. That's where I put the handful
>of new shelves I have.
>
>--
>David Hendley
>Maydelle, Texas
>hendley@tyler.net
>http://www.farmpots.com/
>
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David Hendley on tue 5 dec 00
----- Original Message -----
Edouard Bastarache asks:
>excellent piece of information drawn from years of experience.
>Do you use extra posts under the most important cracks?
>Please discuss this issue.
No, no extra posts. If a cracked shelf can be rotated so the
crack can rest directly on, or next to, a post, it is used in
that position.
In re-reading my message from yesterday, I noticed that
it may sound confusing because I used the word 'piece'
to mean both the 2 halves of a broken shelf and also a
pot being fired in the kiln.
What I meant to say is that, should a kiln shelf break, the
mug or bowl or whatever on the level below the break will
hold the broken halves in place, just a little lower than the
original, pre-break position. All you lose are just a couple
of pots.
Your best shelves should be used on the bottom, if the
shelves span a flame trough as in most downdraft kilns,
because there are no stop-gap pots to hold up the two
halves should the shelf break.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
>I hesitate giving advice because all I have to go on is
>personal experience, or jinxing myself, but.....
>
>I have been using cracked silicon carbide kiln shelves
>for decades. Can't remember the last time one broke,
>probably in the 1980's.
>These shelves are REALLY cracked. Some in two different
>places on the same long side, halfway across, some
>on BOTH sides of the long dimension. ALL of them
>are cracked at least a few inches on both of the
>short dimension sides.
>These shelves are NEVER flipped, since they are heavily
>coated on one side for use in my wood kiln.
>About 1/2 are still flat, 1/4 have sagged down a bit, and,
>believe it or not, 1/4 of them bow upwards!
>
>There is one primo important rule to remember when
>stacking a kiln: Line up the shelf supports directly
>above the one below. One straight line from bottom to top.
>Even if a shelf breaks, it won't do too much damage.
>If it's on the top, the 2 pieces will simply come to rest on
>a couple of pieces on the shelf below.
>If a lower shelf breaks, the weight of the rest of the stack,
>as well as the pieces below, will actually help to hold the
>broken pieces in place.
>The bottom shelf is the most important, because there's
>nothing below to support it. That's where I put the handful
>of new shelves I have.
>
>--
>David Hendley
>Maydelle, Texas
>hendley@tyler.net
>http://www.farmpots.com/
>
..
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