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Hairline cracks in bottom of kiln


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#1 Ray Bright

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Posted 12 October 2012 - 07:02 AM

Got hairline crack. Is this catastrophic?

Ray

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#2 bciskepottery

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Posted 12 October 2012 - 07:10 AM

No. Not an issue or problem. Suggest, as a general practice, putting a shelf supported on 1/2 inch posts to serve as bottom. That gives you some space underneath for air/heat circulation. Plus, avoids wear on the kiln floor.

#3 pattispots

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Posted 12 October 2012 - 07:10 AM

Got hairline crack. Is this catastrophic?

Ray



Wanting to know the answer to this also. But my kiln has several more hairline cracks than Ray's.

Patti

#4 Ray Bright

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Posted 12 October 2012 - 08:19 AM

No. Not an issue or problem. Suggest, as a general practice, putting a shelf supported on 1/2 inch posts to serve as bottom. That gives you some space underneath for air/heat circulation. Plus, avoids wear on the kiln floor.


Good! Also, I've taken this kiln off its rusty old factory issue stand and put it on a heavy duty steel roller dolly. Is this a bad idea?

Attached File  P1030004.JPG   1.73MB   41 downloads


#5 DAY

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Posted 12 October 2012 - 09:42 AM


No. Not an issue or problem. Suggest, as a general practice, putting a shelf supported on 1/2 inch posts to serve as bottom. That gives you some space underneath for air/heat circulation. Plus, avoids wear on the kiln floor.


Good! Also, I've taken this kiln off its rusty old factory issue stand and put it on a heavy duty steel roller dolly. Is this a bad idea?

Attached File  P1030004.JPG   1.73MB   41 downloads


I would put a kiln shelf between the kiln and the dolly, so the entire bottom has support.

#6 JBaymore

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Posted 12 October 2012 - 10:02 AM

Did you check that the top surface of that roller dolly was preciely flat before placing the kiln upon it? If not, then uneven forces on the relatively weak brickwork could have stressed the IFB. Did the cracks show up right after you put it on the dolly?

When you stilt the shelves, if you leave that layout on the dolly the same, make sure that the tri-post system you aer using lines up with the three "arms" that are actually supporting the floor. That will keep the withght of the load wells supported instead of relying on the strength of the IFB.

That IFB is already being internally thermally "stressed" a bit by being hot on one face and cold on the other over only a distance of 21/2 inches. No sense in adding to the working load.

best,

.........................john
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Professor of Ceramics; New Hampshire Insitute of Art

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#7 Ray Bright

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Posted 12 October 2012 - 10:42 AM

Thanks. I'm starting to think I should just go back to the Skutt stand. With those cracks in the bottom, I wonder if I shouldn't build a firebrick on concrete board 'table' to put on the Skutt stand and the kiln on top of that. I have little space in my shop, so the wheeled dolly (which I had sitting around) seemed perfect. But burning down my house is the risk for the benefit of a little comfort.

R




#8 Mark McCombs

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Posted 12 October 2012 - 12:05 PM

I just had this conversation with Skutt a couple weeks ago. They said that it is normal to get fine cracks in the lower slab.

As long as the cracks are not going all the way through you should be fine.

My kiln is sitting on the factory stand with the Envirovent.
Mark
Fast Hawk Pottery


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#9 Lucille Oka

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Posted 13 October 2012 - 02:34 AM

Hair line cracks are usually not a problem but check your kiln with a level and be sure that it is level on all sides.
You may have to fix that.

John 3:16
"For God so loved the world that He gave His only begotten Son, that whosoever believeth in Him should not perish but have everlasting life".

#10 Jime

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Posted 17 October 2012 - 02:58 AM

If it's not impolite, I'll jump on this thread with a similar question. I am a self-taught potter that has never fired. I recently moved from Oregon back home to Costa Rica, and took an electric kiln with me (it was tested before I shipped it, and passed with plying colors). During the move the metal legs buckled and folded, resulting in some decent cracks in the bottom of the kiln. more than hairline, see the attached pictures.

someone recommended using a kiln-repair paste on those bottom cracks, so I had a friend bring some down, but haven't had a chance to use it or test the kiln yet.
My question to you guys, is for tips for a Newbie, on how to baby my kiln to compensate for those cracks. Being in Costa Rica, I can't easily order specialized items, and I can't easily replace that kiln, I need it to last me many years.

I will need to come up with a different base since the metal one is busted. I had never considered that the base needed to be perfectly level. what other things should I consider for the base support? I'll need to MacGyver it, and I had originally thought that I could sit the kiln directly on some cement blocks. bad idea?

thankfully I brought some extra kiln shelves with me, so I have both full and half shelves. should I just plop one on the bottom of the kiln? should I sit one under the kiln to help distribute the load?

thank you all for the amazing resource, this is incredible support.

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#11 bciskepottery

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Posted 17 October 2012 - 07:56 PM

The kiln repair paste should be fine for the major cracks. As the kiln heats, the bricks will expand, so I'd only fill the large ones. I'd sit a full shelf on short posts (1/2 inch) on the bottom -- again, to give some space for air flow during firings. A course or two of bricks can be used as a base; just make sure they are level and have a surface large enough to set the kiln on -- you don't want edges hanging over the sides of the brick base.

#12 Jime

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Posted 25 October 2012 - 10:20 PM

thanks for the great answer!! I too have been worrying about whether this was catastrophic.
it sounds like I can definitely work with it. thanks!

#13 Mark C.

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Posted 26 October 2012 - 11:14 AM

Put a 1/4 flat plate of steel under bricks and this all goes away.
Mark
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www.liscomhillpottery.com

#14 Ray Bright

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Posted 27 October 2012 - 08:32 AM

Put a 1/4 flat plate of steel under bricks and this all goes away.
Mark


I put a 1/2" layer of concrete "Hardy Backer" board under it. Hope for same effect.

#15 Mark C.

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Posted 27 October 2012 - 10:54 AM

Ray
I like your rolling stand-
The hardy backer is good stuff -not a stiff as steel-Its hard to see with your photo how much area is unsupported .
Let us know how its working out.
Mark
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#16 Marcia Selsor

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Posted 27 October 2012 - 08:53 PM

They do not look serious to me. It should not cause any problems
Marcia




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