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Extruding Hollow Cylinders


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#1 Claynut

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Posted 04 October 2010 - 05:13 PM

I have started a new project using my extruder and have never used the hollow dies. My first extrusions were too flimsy so I deduced that they were to big in diameter to work for my application (the rim of a large flower pot). I didn't want to waste the clay or go through the trouble of drying it to reclaim it so I wedged the extrusions and put it back in the extruder. As a result some of my tubes still had a few holes in them. I plan on poking holes in the interior of each rim tube and slow bisquing. This is cone 10 black mountain clay should I be concerned that it will still blow parts off in the firing (bisque or glaze?) I wanted to once fire them actually and now I'm a little scared they will blow up so I thought I should bisque them to make sure they will be able to handle the cone 10 firing. I dont' want a mess to clean up in my kiln.

Your thoughts and experiences would be appreciated. Thanks :)

#2 Marcia Selsor

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Posted 04 October 2010 - 08:51 PM

Fire slow. Steam in air pockets is the problem. Put pin holes in them. Try to compress when possible. After glazing go slow too.

Marcia

#3 BradP

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Posted 05 October 2010 - 09:16 AM

I have started a new project using my extruder and have never used the hollow dies. My first extrusions were too flimsy so I deduced that they were to big in diameter to work for my application (the rim of a large flower pot). I didn't want to waste the clay or go through the trouble of drying it to reclaim it so I wedged the extrusions and put it back in the extruder. As a result some of my tubes still had a few holes in them. I plan on poking holes in the interior of each rim tube and slow bisquing. This is cone 10 black mountain clay should I be concerned that it will still blow parts off in the firing (bisque or glaze?) I wanted to once fire them actually and now I'm a little scared they will blow up so I thought I should bisque them to make sure they will be able to handle the cone 10 firing. I dont' want a mess to clean up in my kiln.

Your thoughts and experiences would be appreciated. Thanks Posted Image



#4 BradP

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Posted 05 October 2010 - 09:20 AM

I had the same problem with wet clay extruded cylinders. I put a table under the extruder and extruded a cylinder about two feet long. I put a bat under it and extruded it until it touched the bat. I let it hang full length with a small fan on it. I worked on other projects until it dried enough to stand on its own then I cut it off with my wire. If you need it in a real hurry this may not be applicable but I multi task and it is so much less frustrating to work on a cylinder that stands on its own then to fight with a collapsing piece of clay.

Brad

#5 Seasoned Warrior

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Posted 05 October 2010 - 11:44 AM

I had the same problem with wet clay extruded cylinders. I put a table under the extruder and extruded a cylinder about two feet long. I put a bat under it and extruded it until it touched the bat. I let it hang full length with a small fan on it. I worked on other projects until it dried enough to stand on its own then I cut it off with my wire. If you need it in a real hurry this may not be applicable but I multi task and it is so much less frustrating to work on a cylinder that stands on its own then to fight with a collapsing piece of clay.

Brad


I kinda do the same Brad but I use a propane torch, it's much quicker than a fan. I also use the propane torch to firm up work on the wheel sometimes if it's really thin and has a tendency to slump.

Best regards,
Charles




#6 Claynut

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Posted 05 October 2010 - 12:07 PM

Fire slow. Steam in air pockets is the problem. Put pin holes in them. Try to compress when possible. After glazing go slow too.

Marcia



Thanks :). I am tempted to put a pin hole design all along the rim so I dont have to worry about it. These pots will end up being the only thing in my kiln because they are pretty big so it would be nice for it to succeed. I get pretty bummed out when I ruin everything in a load from some blunder :)

#7 Claynut

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Posted 05 October 2010 - 12:10 PM

I had the same problem with wet clay extruded cylinders. I put a table under the extruder and extruded a cylinder about two feet long. I put a bat under it and extruded it until it touched the bat. I let it hang full length with a small fan on it. I worked on other projects until it dried enough to stand on its own then I cut it off with my wire. If you need it in a real hurry this may not be applicable but I multi task and it is so much less frustrating to work on a cylinder that stands on its own then to fight with a collapsing piece of clay.

Brad



That's a good idea, I like it. I do have a heat gun I could use for that. I needed 6 cylinders 16 " long for the rim of two pots and 2 22" long for the base of the pot to attach my feet to so I was a little impatient to wait for them to be strong. I reduced the size and increased the thickness in the clay to 1/2 " and had much better luck with bending them into arc's. Now i'm onto working on the feet :)




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