search  current discussion  categories  tools & equipment - extruders 

air pockets in extruder

updated tue 15 apr 08

 

Lou Roess on sun 13 apr 08


Does anyone have any thoughts on how to keep extruded coils from
having air pockets that "pop" as the coil is extruded. They can be
fixed but I'd rather eliminate them.
I wedge the clay thoroughly just before using it so the air must get
in when I am loading the clay into the tube.
I have a Northstar with a square barrel, and make a large short
coil that clears all the sides as I load it. Then I push the plunger
down to flatten the clay, add another coil, and flatten and so on
until the barrel is full.
What can I do differently to avoid the pooping?
Any and all help appreciated.
Thanks,
Lou in Colorado

Larry Kruzan on mon 14 apr 08


Hi Lou,

I also have the Northstar and a Bailey extruder system - both are great
extruders but if I try to add one lump on top of another like you describe
air pockets are going to be present. Try filling the chamber with one
larger lump of clay instead of the smaller coils. The closer it conforms to
the chamber shape and size the fewer air pops you will have.

I also LIGHTLY spritz the chamber every few loads with WD40. I feel that it
keeps things moving smoother (Ex-Lax had this idea years ago) and allows
trapped air to escape around the plunger. I cannot prove this by any
scientific study but it works for me.

Lastly, I go straight from a de=airing pugmill to the extruder - I hate
wedging. I rarely have many air pops.


Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com




-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Lou Roess
Sent: Sunday, April 13, 2008 5:49 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: [CLAYART] Air pockets in extruder

Does anyone have any thoughts on how to keep extruded coils from
having air pockets that "pop" as the coil is extruded. They can be
fixed but I'd rather eliminate them.
I wedge the clay thoroughly just before using it so the air must get
in when I am loading the clay into the tube.
I have a Northstar with a square barrel, and make a large short
coil that clears all the sides as I load it. Then I push the plunger
down to flatten the clay, add another coil, and flatten and so on
until the barrel is full.
What can I do differently to avoid the pooping?
Any and all help appreciated.
Thanks,
Lou in Colorado

____________________________________________________________________________
__
Clayart members may send postings to: clayart@lsv.ceramics.org

You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here:
http://www.acers.org/cic/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com

Dale Neese on mon 14 apr 08


Lou,
it is when you are loading the barrel of the extruder that you are creating
air pockets. I suggest loading the extruder with one solid amount of wedged
clay instead of the coils. The compress the plunger. Less chance of creating
air.

Dale Tex
"across the alley from the Alamo"
San Antonio, Texas USA
http://www.daleneese.com

David Hendley on mon 14 apr 08


To reduce pop-outs, try to shape the clay so it will
exactly fir the barrel. You want it to slide down, but with
very little space around it.
I think adding the clay a little at a time gives more
opportunity for the air pockets to form.
I don't have any hints for eliminating pooping.
David Hendley
Maydelle, Texas
david(at)farmpots(dot)com
http://www.farmpots.com


----- Original Message -----
> Does anyone have any thoughts on how to keep extruded coils from
> having air pockets that "pop" as the coil is extruded. They can be
> fixed but I'd rather eliminate them.
> I wedge the clay thoroughly just before using it so the air must
> get
> in when I am loading the clay into the tube.
> I have a Northstar with a square barrel, and make a large short
> coil that clears all the sides as I load it. Then I push the plunger
> down to flatten the clay, add another coil, and flatten and so on
> until the barrel is full.
> What can I do differently to avoid the pooping?
> Any and all help appreciated.
> Thanks,
> Lou in Colorado

Taylor Hendrix on mon 14 apr 08


Hey David,

I know you're one of the experts in all this, but I feel eliminating
pooping is redundant.

Call me crazy...

Taylor, in Rockport TX

On Mon, Apr 14, 2008 at 12:48 AM, David Hendley wrote:
...
> I don't have any hints for eliminating pooping.
> David Hendley
...

Steve Mills on mon 14 apr 08


From experience: only load one "log" at a time and extrude it. It's when you load 2 or more the air gets trapped betwwen the "logs"

Steve
Bath
UK

Lou Roess wrote:
Does anyone have any thoughts on how to keep extruded coils from
having air pockets that "pop" as the coil is extruded. They can be
fixed but I'd rather eliminate them.
I wedge the clay thoroughly just before using it so the air must get
in when I am loading the clay into the tube.
I have a Northstar with a square barrel, and make a large short
coil that clears all the sides as I load it. Then I push the plunger
down to flatten the clay, add another coil, and flatten and so on
until the barrel is full.
What can I do differently to avoid the pooping?
Any and all help appreciated.
Thanks,
Lou in Colorado

______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org

You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/

Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com