James Freeman on sun 21 aug 11
I have used my small Brent extruder for many years to form small structural
components, without any problems. Five or six years ago I purchased the
large Bailey extruder with the 9" expansion box, with the idea of playing
around with large extrusions. It served as a very nice wall decoration
until I finally got around to trying it out yesterday with some of the
collection of dies I got from an art fair potter who went out of business.
Ended up wasting half a day, and salvaged nothing.
The dies I used were all for medium to large, hollow forms. The 12" long o=
r
so extrusions were massively thick, a good 3/8", and weighed about 5 pounds
each, which may go a long way toward explaining why the previous owner of
the dies went out of business. I will need to fashion new, much larger
internal "plugs" for the center of the dies in order to thin the walls to
something reasonable, but the question is, how thick should the walls be?
When I throw, my walls are usually 1/8" or so in thickness (except at the
rim). I imagine this might be too thin for an extrusion, so am thinking
perhaps 3/16", or at most 1/4". Any thoughts or advice?
The second problem pertains to cleaning the dies after use. These dies are
made of 1/2" baltic birch plywood. The internal "plug" is attached to the
outer form via bridges cut from stainless steel angle iron. My second
question is; how the heck do you clean these things? I tediously dug as
much clay as I could from on and around the die and bridgework using a
wooden rib. This left lots of clay stuck in the gap in the die, in the hol=
e
through the bridgework, and around the bolts holding the bridgework in
place. So, is one supposed to unbolt all of the bridgework to facilitate
cleaning? Scrub around everything with a toothbrush? I decided to let the
clay completely dry on the die, and am hoping it will soak off or slake
apart once dry. Again, thoughts or advice?
The third problem pertains to the actual extrusions. I was very careful
about centering the die (symmetric form), yet the extrusions all had minor
curves or wiggles. I suppose the easy answer is to embrace the wonkiness
and pretend that the forms are "expressive", but how does one extrude
perfectly straight forms? Is this possibly the result of using too soft of
clay? (I used reclaim that was not sticky, but was too soft for throwing.
This reclaim extruded well through much smaller dies in my Brent extruder.)
I cut off the extrusion nice and square by running a wire along the die's
rails, leaving a 3/4" stub of extruded clay protruding from the die. When =
I
began to extrude the next form, the beginning of the extrusion tended to
close in a fair bit. Is there a secret to obtaining extrusions which are
straight-sided along their entire length, or must one tease the closed in
area back out by hand? Again, might this be the result of too soft of clay=
?
How does one deal with "blow outs" in the extruded form? Does one salvage
the form by filling the divot, or is it common practice to just scrap the
piece?
The last question involves extrusion as a production method in general.
Changing dies was pretty much a nightmare, as the bridgework was firmly
embedded in the mass of clay filling the expansion box. Cleanup was also a=
n
incredibly time consuming and tedious operation, having to dig wads of clay
out of the dies, the expansion box, and the extruder barrel. It seems to m=
e
that unless one is extruding a tremendous quantity of pieces using only one
die, it could very well be much faster to simply hand build or
throw-and-alter the forms. Any thoughts? Am I missing something? Would
spraying the inside of the expansion box with WD-40 prior to use aid in
cleanup?
Thanks in advance for any help or advice.
All the best.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
William & Susan Schran User on sun 21 aug 11
On 8/21/11 10:23 AM, "James Freeman" wrote:
>
> The dies I used were all for medium to large, hollow forms. The 12" long=
or
> so extrusions were massively thick, a good 3/8", and weighed about 5 poun=
ds
> each, which may go a long way toward explaining why the previous owner of
> the dies went out of business. I will need to fashion new, much larger
> internal "plugs" for the center of the dies in order to thin the walls to
> something reasonable, but the question is, how thick should the walls be?
> When I throw, my walls are usually 1/8" or so in thickness (except at the
> rim). I imagine this might be too thin for an extrusion, so am thinking
> perhaps 3/16", or at most 1/4". Any thoughts or advice?
You will have to try a couple different thicknesses to find what works best
for you with the length of the hollow extrusion. Since you want to use
fairly moist clay to get good extruded forms without tears or textures,
often you must sacrifice thinner walls to get a stable form that will not
slump when cut from the extruder. One way around this to allow for thinner
walls would be to use a heat gun to stiffen the form a bit before cutting
loose.
> The second problem pertains to cleaning the dies after use. These dies a=
re
> made of 1/2" baltic birch plywood. The internal "plug" is attached to th=
e
> outer form via bridges cut from stainless steel angle iron. My second
> question is; how the heck do you clean these things? I tediously dug as
> much clay as I could from on and around the die and bridgework using a
> wooden rib. This left lots of clay stuck in the gap in the die, in the h=
ole
> through the bridgework, and around the bolts holding the bridgework in
> place. So, is one supposed to unbolt all of the bridgework to facilitate
> cleaning? Scrub around everything with a toothbrush? I decided to let t=
he
> clay completely dry on the die, and am hoping it will soak off or slake
> apart once dry. Again, thoughts or advice?
I would advise against soaking any wood product in water to remove clay. No
matter how good the plywood, you will eventually cause delaminating. Either
scrub off wet clay with stiff brush dipped in water or allow the clay to dr=
y
and scrape/scrub off outside the studio.
> The third problem pertains to the actual extrusions. I was very careful
> about centering the die (symmetric form), yet the extrusions all had mino=
r
> curves or wiggles. I suppose the easy answer is to embrace the wonkiness
> and pretend that the forms are "expressive", but how does one extrude
> perfectly straight forms? Is this possibly the result of using too soft =
of
> clay? (I used reclaim that was not sticky, but was too soft for throwing.
> This reclaim extruded well through much smaller dies in my Brent extruder=
.)
Once you begin the extrusion, do not stop or hesitate as this will cause
much unevenness. If you do have unwanted wonky forms, wait til stiffer and
paddle or straighten with a couple boards.
> I cut off the extrusion nice and square by running a wire along the die's
> rails, leaving a 3/4" stub of extruded clay protruding from the die. Whe=
n I
> began to extrude the next form, the beginning of the extrusion tended to
> close in a fair bit. Is there a secret to obtaining extrusions which are
> straight-sided along their entire length, or must one tease the closed in
> area back out by hand? Again, might this be the result of too soft of cl=
ay?
The beginning of the extrusion will always be a bit off, never even. Think
about making a miter box that the stiffened extrusion can lie in and you ca=
n
then cut a right angle using a VERY thin wire. I use a Ergo-Thin wire from
Dirty Girls Tools -
http://www.kentuckymudworks.com/tools/dirtygirlstools.html
I use this wire to cut under thrown porcelain forms without bottoms and hav=
e
no problems with distortion of the form. I think this thin type wire should
work well for cutting extruded forms without distorting the shape.
> How does one deal with "blow outs" in the extruded form? Does one salvag=
e
> the form by filling the divot, or is it common practice to just scrap the
> piece?
Good wedging or running clay through de-airing pug mill, but see no reason
you can't just fill to divot - let extrusion stiffen first.
> The last question involves extrusion as a production method in general.
> Changing dies was pretty much a nightmare, as the bridgework was firmly
> embedded in the mass of clay filling the expansion box. Cleanup was also=
an
> incredibly time consuming and tedious operation, having to dig wads of cl=
ay
> out of the dies, the expansion box, and the extruder barrel. It seems to=
me
> that unless one is extruding a tremendous quantity of pieces using only o=
ne
> die, it could very well be much faster to simply hand build or
> throw-and-alter the forms. Any thoughts? Am I missing something? Would
> spraying the inside of the expansion box with WD-40 prior to use aid in
> cleanup?
I would suggest a vegetable spray instead of the petroleum based WD40.
Yes, changing out dies is a pain, so simply planning to extrude all one for=
m
for a series before moving on to the next shape is the best advice.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
James Freeman on tue 23 aug 11
On Sun, Aug 21, 2011 at 10:23 AM, James Freeman <
jamesfreemanstudio@gmail.com> wrote:
I have used my small Brent extruder for many years to form small structural
components, without any problems. Five or six years ago I purchased the
large Bailey extruder with the 9" expansion box, with the idea of playing
around with large extrusions. It served as a very nice wall decoration
until I finally got around to trying it out yesterday with some of the
collection of dies I got from an art fair potter who went out of business.
Ended up wasting half a day, and salvaged nothing.
-------------
I would like to thank everyone who provided me with tips and advice on my
extruding question. In addition to Bill's on-list post, I received a rathe=
=3D
r
large number of off-list messages bearing a wealth of good advice. I tried
to respond to and thank each person individually, and if I missed anyone,
you have both my apologies and my thanks. As an aside, with many of the
questions I have posted lately, the off-list responses seem to outnumber th=
=3D
e
on-list by a good 3 or 4 to one, or even more. I do understand why this is=
=3D
,
and have sent many off-list responses myself for various reasons, but the
consequence is that a lot of good information is not widely shared.
In any case, I received one response from a former clayart member that was
very different from the rest. It tied many of the problems I experienced t=
=3D
o
the expansion box rather than to extruding per se, and offered some
suggested modifications which confirmed a suspicion I had, and which I
intend to employ and to document. With his permission, I am sharing part o=
=3D
f
that email below:
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D
James, I noticed your extruder questions on Clayart. (I no longer
participate directly in Clayart, but I do occasionally check the postings o=
=3D
n
the Yahoo Groups page.) I don=3D92t know the answers to most of your quest=
io=3D
ns,
but thought I could provide some information on your third question about
=3D93curves or wiggles=3D94 in the extrusions.
I have a Bailey extruder with the expansion box that I have had for a numbe=
=3D
r
of years. One of my friends was a Chemical Engineering Professor at the
University of Texas at Austin (now retired). He was an expert in plastics
and extrusions among other topics. A number of years ago (in the 1980s) he
had some graduate students looking for a lab/research project. They were
interested in the general topic of extrusions and for some reason could not
get time during that period on the plastics machines at the university. He
knew I had the clay extruder and asked if they could borrow it and some cla=
=3D
y
and do some analysis. In return I got the final report. They actually use=
=3D
d
both the expansion box extruder and a barrel extruder I had and compared
results. They did all sorts of analysis looking at the moisture content of
the clays, position of the dies, etc. They, of course, found that the
barrel extruder worked best with centered dies as you would expect. They
also found that the expansion box created a number of issues that made it
difficult to get =3D93straight=3D94 extrusions. Even with the die centered=
and
symmetrical around the center there is a problem with the clay effectively
=3D93bunching up=3D94 in the corners of the expansion box and creating a no=
n-ev=3D
en
pressure across the die =3D96 sort of an eddy current effect. This results=
i=3D
n
curved extrusions. They tried a number of solutions. They used both
computer models and actual experiments to test the various solutions. I
don=3D92t remember all of the potential solutions, but they included =3D96
1. Building a series of baffles across the center of the expansion bo=
=3D
x
to evenly distribute pressure. They tried numerous baffles and all sorts o=
=3D
f
baffle surfaces.
2. Building the baffles so they were also the =3D93bridge=3D94 you me=
ntio=3D
ned
that held the center plug in place.
3. Putting one or more chains (of different size and configuration)
across the expansion box. (This was a solution we had found in some
potter=3D92s book.)
4. Blocking off the corners of the expansion box by filling it in wit=
=3D
h
pieces of wood cut at 45 degrees so that the clay did not go into the side=
=3D
s
of the box The pieces of wood were screwed to the side of the box through
some holes they drilled. The overall effect was that a cross-section view
of the inside of the expansion box was no longer a rectangle, but was a
4-sided, truncated pyramid with 45 degree walls.
As I said, there were other solutions modeled and tested, but I don=3D92t
remember the details.
The results were that solution 4 with the 45 degree angles was determined t=
=3D
o
give the best results by far. I have used the extruder with the wooden
blocks in place, but a) have not used it much, and b) have not used it
seriously in many years. The block modification did make a real difference=
=3D
,
but I don=3D92t remember that it was perfect. (The biggest improvement was=
w=3D
ith
dies that were not symmetrical around the center of the extruder.)
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D
All the best.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Robert Klander on tue 23 aug 11
Hi James...
Do you think your friend might send a photo of the expansion box showing th=
e
modification?
I believe a number of us would be interested in seeing an image!
Best thoughts for successful extrusions!
Robert
******************
4. Blocking off the corners of the expansion box by filling it in wit=
h
pieces of wood cut at 45 degrees so that the clay did not go into the side=
s
of the box The pieces of wood were screwed to the side of the box through
some holes they drilled. The overall effect was that a cross-section view
of the inside of the expansion box was no longer a rectangle, but was a
4-sided, truncated pyramid with 45 degree walls.
As I said, there were other solutions modeled and tested, but I don't
remember the details.
The results were that solution 4 with the 45 degree angles was determined t=
o
give the best results by far. I have used the extruder with the wooden
blocks in place, but a) have not used it much, and b) have not used it
seriously in many years. The block modification did make a real difference=
,
but I don't remember that it was perfect. (The biggest improvement was wit=
h
dies that were not symmetrical around the center of the extruder.)
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D
=3D=3D=3D=3D=3D=3D
All the best.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
James Freeman on wed 24 aug 11
On Tue, Aug 23, 2011 at 6:25 PM, Robert Klander wrote:
Do you think your friend might send a photo of the expansion box showing th=
e
modification?
I have uploaded several extruder related photos to my Flickr page (
http://www.flickr.com/photos/jamesfreemanstudio/).
I uploaded two photos of the extruder expansion box with the wooden filler
blocks in place, and a drawing with dimensions and angles should you wish t=
o
fashion your own. These were provided by the gentleman whose expansion box
information I shared in an earlier post.
The next two photos are copies of my plans for making the Under $10 Caulkin=
g
Gun Extruder that I mentioned in some of my replies. This is actually a
handout I made when I presented my workshop at Edinboro University (My
first, and my last!). All of the required materials to make your own
extruder can be obtained from any home center or hardware store. It works
extremely well for smaller extrusions, and I find myself using it far more
often than either of my other two extruders. I used it to fashion all of
the "angle iron" and "band iron" hardware on my new series of Industrialwar=
e
vessels. I have also uploaded photos of some of these vessels (sans glaze)
so you can see the hardware in place.
All the best.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
C. Tullis on sun 11 sep 11
I know it's been a while since you posted clayart about your difficulties=
=3D
with your=3D20
extruder but I thought this book would be of some help.
http://www.amazon.com/Ceramic-Extruding-Inspiration-Tom-
Latka/dp/0873419030
Tom and Jean pretty much cover everything that you talked about.
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