Dave Hedblom on sat 29 mar 97
I have Walker Pug Mill and would like to add de-airing. I am very
mechanically incline and would have no problem doing this if is possible.
That's the question. Is it possible? Has anyone ever done this before? I
have never seen a de-airing system before so I'm at a loss as where to start.
thanks
dave heablom
claymoon@conline.com
it was 65 deg yesterday!!!!!!!!!!!!!!!
Vince Pitelka on sun 30 mar 97
At 08:52 AM 3/29/97 -0500, you wrote:
>----------------------------Original message----------------------------
>I have Walker Pug Mill and would like to add de-airing. I am very
>mechanically incline and would have no problem doing this if is possible.
>That's the question. Is it possible? Has anyone ever done this before? I
>have never seen a de-airing system before so I'm at a loss as where to start.
Dave -
I will be interested to hear what others have to say about his, but I do not
think this is a very practical idea, even with MAJOR modifications to your
Walker. Since the Walker has a support bearing on the extrusion end, and
the extrusion is at right angles to the shaft, the clay is really compressed
in the last part of the barrel. In other words, it moves slower there than
in the first part of the barrel. The single-shaft de-airing system in
common use today, which was invented by Harry Davis and cronies, purchased
by Venco, and "borrowed" by Bluebird, requires that the clay move FASTER in
the second half of the barrel than the first half, to prevent the vacuum
chamber from becoming clogged with clay. These mills force the clay through
shredder screens, and the resulting clay "spagetti" is thus all exposed to
the vacuum. The clay is under pressure as it enters the screens, and under
pressure again at the end of the mill where it is extruded, so the vacuum
pump is able to maintain a vacuum in the zone inbetween. But this does
require that the "spagetti" remain loose and open for a bit inside the
vacuum zone. I do not see this would be possible with a Walker, unless you
converted to a system where the main shaft is entirely supported at the
power end (in order to have a straight rather than 90 degree extrusion), and
I'm not sure the Walker shaft is heavy enough for that. The de-airing
system also requires pairs of half-helixes before the shredder screens and
before the extrusion, and the Walker operates entirely on blades rather than
helixes.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts
1560 Craft Center Drive, Smithville TN 37166
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