Jonathan Kaplan on mon 13 jul 98
We have used a Bailey pneumatic since they came on the market with no problem.
Some suggestions:
*Make sure you have enough air pressure. Different extrusion configurations
require lots of air, some require smaller amounts. Die syze, shape,
configuration, etc., all require paying attention to the air pressure.
*Spray the inside of the barrel and the plunger with WD 40 to facilitate
cleaning.
*We use 1/4" plexiglass dies that are backed up with birch plywood for strength.
*Bevel the inside edge of the die to allow the clay to flow naturally into
the die opening.
*We have also constructed many hollow dies using plex/wood and Jim Bailey's
internal die holders. These work very well in the standard die barrels as
well as in the expansion box.
*Clay consistency is crutial for all types of extrusions, as is using well
pugged clay.
*Large hollow extrusions require some sort of cut off device and parting
table, even a second persion to assist.
When properly used, the Bailey system is indeed a great tool. Thanks Jim!!
Jonathan
Jonathan Kaplan http://www.sni.net/ceramicdesign/
http://www.ceramicsoftware.com/education/clay/kaplan1.htm
jonathan@csn.net
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Joyce Lee on sat 17 jun 00
I'd like to be able to attach tall, hollow cylindrical extrusions on my
Shimpo and then throw them. Seems to me that should work well ... a
cylinder being a cylinder, after all, and the form with which I usually
start most of my pots. I HAVE been able to throw the shorter cylinders,
but have to settle for a less than symmetrical shape..... which works
well for some forms. Would any of you extruder users be willing to
speculate as to the reasons I cannot do such a simple task? I may be
leaving out something significant. I'm working solely on the smaller,
hollow round form until I become familiar with the process. I sometimes
attach a slab bottom before attaching the cylinder to the wheel;
sometimes I don't ... same results. The clay is VERY compressed, of
course. Seems simple. Not ...... so far. Sort of rips when I try
throwing. Maybe this isn't worth fooling with ... I can and do throw
cylinders daily .... the wish to throw an extrusion is just a passing
fancy... but perhaps one of you knows what I'm talking about and could
offer a suggestion??? Thank you as always for thinking of me...
Joyce
In the Mojave up since 3 a.m. and enjoying the early morning cool ...
hearing echoes of hammering over at the adjoining corral ... our young
neighbor who just passed the Police Academy Exam (different strokes...)
is probably repairing the shelter where Big Red used to kick big holes
... before one morning he was gone.......and I with sugar cubes still in
my pockets.......
GURUSHAKTI@AOL.COM on sat 17 jun 00
Hi Joyce:
If the cylinder idea isn't working (seems like it should, doesn't it???),
then you might use your extruder to make flattened coils and just add and
throw coils to an already started, thrown cylinder. This is what I've seen
them do in Japan and they throw huge pots using this method. You could shape
the die to have the extruded clay have a sloping angle on one side and then
slope the edge of your thrown started cylinder in the opposite directions.
This will give a better join and trying to join two straight cut rims. The
extruder die hole would look like this, just bigger.
_______________________________
l /
l /
l _____________________________/
I think I have this right! :-) This size can be adjusted for the maximum size
opening recommended for your dies and your preference for how thick you want
the coil (squarish coil) to be. The width as shown, will the height of the
squarish coil and the angled side, on the right, is the side that you will
place on top of the pot on the wheel which have the rim angled the other way
I don't know how thick the cylinders are that you are extruding. Have you
tried various thicknesses?
It will be interesting to see if any Clayarters have had a go and any success
with the extruded cylinders.
Warm regards,
June
Ray Aldridge on sun 18 jun 00
At 09:57 AM 6/18/00 -0600, Cindy wrote:
>Joyce, You're starting with a tall, thin object which cannot be perfectly
>centered, and which is unstable by nature of its shape and degree of
>hardness. You might be able to throw it on one of the upside down wheels
>I've occasionally heard tell of, but I think there's going to be a definite
>upper limit to the height of an extrusion you can throw on a normal wheel.
Joyce, this may not be useful, since it's entirely theoretical, but if I
were attempting to throw a tall extrusion, the first thing I'd try would be
collaring the extrusion in as much as practical (collar it in until your
inside hand will just fit down the throat of the extrusion.) Then when you
pull, you might get a better consistency. Again I emphasize that this is
only a theory, but you would be to some extent duplicating the coning
process that can help to even out minor inconsistencies in the clay.
Ray
Aldridge Porcelain and Stoneware
http://www.goodpots.com
Jennifer Boyer on sun 18 jun 00
Joyce,
People are giving you some good ideas about how to throw tall.
Noone has talked about why throwing extrusions seems to be not
working. I think that the compression clay goes through in the
extruder is SO different from the compression of throwing that
the clay platelets in the extrusion are set up all wrong for
throwing. So when you put the clay through the stress of
throwing, there are weaknesses in the wall that can't take the
torque of throwing.
Take Care, and keep experimenting!
Jennifer
GURUSHAKTI@AOL.COM wrote:
>
> Hi Joyce:
>
> If the cylinder idea isn't working (seems like it should, doesn't it???),
>
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Thistle Hill Pottery
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http://www.thistlehillpottery.com/
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Cindy Strnad on sun 18 jun 00
Lee and Joyce,
Lee, what a wonderful idea. I really enjoyed reading this, and though I
don't think I'll try it, it's just the sort of thing one loves to know
about. Thanks.
Joyce, You're starting with a tall, thin object which cannot be perfectly
centered, and which is unstable by nature of its shape and degree of
hardness. You might be able to throw it on one of the upside down wheels
I've occasionally heard tell of, but I think there's going to be a definite
upper limit to the height of an extrusion you can throw on a normal wheel.
Granted, that upper limit will increase with practice, but I'll be you find
it has a limit beyond which you can't go. I believe you'll find it is much
more practical to simply throw a cylinder.
One thing you might consider, though, since you have such a large extruder:
Try extruding thick-walled but short cylinder sections and using them to
stack and throw taller cylindrical pots. You'll need to allow the lower
levels to dry a bit before adding another section, of course. I recommend a
tongue and groove configuration for the attachment areas. Base with a rim
like this: ^, and the underside of the section to be added like this: ^: so
that they fit together. You see?
Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
Lee Love on sun 18 jun 00
Joyce,
One way to stretch your ability to throw tall, uniform cylindars is
to use the Old Enlish pitchter method. I learned about this from John
Reeve at a workshop he gave at Northern Clay Center. He discovered it
when some folks from the museum brought him Old English pitchers to examine
and help them figure out how they were thrown. (Related: Shimaoka discovered
rope impresson, Jomon, making reproductions of Jomon pottery.) What John
saw, was that what these potters threw a cylindar upside down, often
attaching a pancake to the top of the clyindar. This is why the foot of
these pots have pinched edgeds. You set the cylindar aside for a
little while, and then you cut it from the bat and flip it over so the
partially dry pancake is a little firm and is now sitting on the bat, held
there with some clay.
Now, you have the thick bottom of the cylindar at the top and
you pull that up to complete your form. There are several advantages of
throwing this way: number one, you can more easily throw taller cylindars.
It is easy to make the bottom the same thickness as the top. Also, the
bottom dries ahead of the top so you can dry quickly without worrying about
bottom cracks. With the pancakes I use, I make sure and leave the wire
cut marks, so they are visible on the bottom of the finished pitcher. If
you finish them carefully, nobody can tell how you did it, if you don't want
them too. Or, to can pinch them on so people can see your process, it is
your choice. The main reason I have used John's technique is for quick
drying. John is another one of those "Leach potters" who doesn't believe
in any secrets.
When I am done studying here in Mashiko, one of my focuses will be
on pitchers and other things with pulled handles. it is something that
we seem to have "a handle on" in the West and I want to share here.
--
Lee Love
Nanai , Mashiko-machi ,Tochigi-ken 321-4106 JAPAN Ikiru@kami.com
Voice Mail and Faxes (a USA number): (303) 256-0374
Help E.T. Phone Earth: http://setiathome.ssl.berkeley.edu/
Des Howard on mon 19 jun 00
Joyce
When you say the clay "rips".
Are the rips vertical, horizontal or spiral?
Are they equally spaced?
Are they the same number as the legs of the extruder die spider?
Des
Joyce Lee wrote:
> I'd like to be able to attach tall, hollow cylindrical extrusions on my
> Shimpo and then throw them. Seems to me that should work well ... a
> cylinder being a cylinder, after all, and the form with which I usually
> start most of my pots. I HAVE been able to throw the shorter cylinders,
> but have to settle for a less than symmetrical shape..... which works
> well for some forms. Would any of you extruder users be willing to
> speculate as to the reasons I cannot do such a simple task? I may be
> leaving out something significant. I'm working solely on the smaller,
> hollow round form until I become familiar with the process. I sometimes
> attach a slab bottom before attaching the cylinder to the wheel;
> sometimes I don't ... same results. The clay is VERY compressed, of
> course. Seems simple. Not ...... so far. Sort of rips when I try
> throwing. Maybe this isn't worth fooling with ... I can and do throw
> cylinders daily .... the wish to throw an extrusion is just a passing
> fancy... but perhaps one of you knows what I'm talking about and could
> offer a suggestion??? Thank you as always for thinking of me...
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
Lynspots@AOL.COM on tue 20 jun 00
Joyce and all,
One thing I learned on my own and that works great for me when throwing
cylinders, is that after the first couple of pulls, depending on how high the
piece will be, get the top part of the cylinder close to how you want it when
done. Meaning get the rim smooth and shaped, thin out the top of the
cylinder, then gradually work with the clay towards the bottom, bringing it
up and thinning it out. If I leave the top too thick, the bottom will rip
because it is too soft and thin to take the torque I am exerting on the top.
Hope this helps, claybud.
And the thing about keeping the clay soft enough is soooo important. I used
to use recycled clay from a studio for years and had so many throwing
problems until I took it in a softer form to wedge and throw. So much
frustration and so easy to solve. I could have kicked myself. It's hard
enough learning all that new stuff without having to fight the clay, too.
Lynne Antone
Beaver Creek Arts
Olympia WA USA
Now if you want to make really big cylinders, I'll tell you some time how
Peter King makes slabs, rolls them around a form, attaches them to a bottom
on the wheel and then throws huge planters to finish. Amazing. So heavy, I'd
need the SO's help to take them off the wheel.
In a message dated 6/17/00 9:41:32 AM Pacific Daylight Time,
Joycelee@IWVISP.COM writes:
<< I'd like to be able to attach tall, hollow cylindrical extrusions on my
Shimpo and then throw them. ........ I sometimes attach a slab bottom before
attaching the cylinder to the wheel; sometimes I don't ... same results. The
clay is VERY compressed, of course...... Sort of rips when I try throwing.
Maybe this isn't worth fooling with ... I can and do throw cylinders daily
.... the wish to throw an extrusion is just a passing fancy... but perhaps
one of you knows what I'm talking about and could offer a suggestion??? Thank
you as always for thinking of me...>>
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