Paul Stubbs on mon 15 may 00
I have lately gotten involved (as translator, etc.) in building a
de-airing pugmill from the plans in Harry Davis' book, the Alternative
Potter. If anyone has any experience with this pugmill, I would like to
know
the answers to the following questions:
1. What size motor does it need?
2. What size vacuum pump/motor?
3. What's the vacuum gauge supposed to read?
Anybody has any good tips resulting from experience as to modifying the
construction, etc., it's not too late, and I'm interested.
Thanks,
Nikom in Thailand
Dear Nikom
There seems to be a lot of discussion on this project at the moment. I
have already written to Don Beckman San Orchid Guest Lodge Thai,
Nongkhai Thailand are you aware of him?
I built one of these machines some 30 years ago and it is still going
strong. I used some of HDs original drawings and scaled them down to
give
a barrel size of 6" with 4" outlet I used a 2hp motor with an inline
gearbox mounted below the frame and connected to the shaft above with a
"duplex" chain This is more than adequate, 1 hp would be sufficient for
this size but was all that was available at the time. If you are
building to the size as in the book then 2 hp would be fine. The first
vacuum pump I used was a small lab sized pump that had a 1/4 hp motor
running it, not sure of the pumps displacement. The volume of air you
will be removing is quite small so it is more important to be able to
run to a vacuum around 25" of mercury to get the best de-airing. I later
went on to use a small milking machine vacuum pump as the original one
had problems with the seals on the bearings. This too is fine, bigger
than it needs to be IM sure but it does not over evacuate the chamber.
Hope this is of some use. There is a picture of it in Hamers Dictionary
look under extruding. I have plenty of pictures if you are interested ?
Regards Paul in warm Somerset. Have many pictures
--
--
Paul Stubbs & Julia Manning.
2 Rosebank,
Queen Street,
Keinton Mandeville.
Somerset.
TA11 6EQ
England.
Craig Martell on tue 16 may 00
Hi:
Venco pugs are fashioned after Harry's pug plans. With permission from
Harry, I might add.
We used to get mills here in the states with 1.1 Kw motors which is about a
1.5 HP motor. During the cold months, if one was working in unheated
quarters, this hp rating was not adequate. So Venco upped the motor to 1.5
Kw, which is 2 Hp and everything was fine. I think that a 1Hp motor for a
mill this size would not be enough. If you can afford this sort of thing,
SEW Eurodrive sells inline parallel helical gearboxes and industrial grade
motors for this sort of thing. This is what Venco uses. They are tough,
well made units. Eurodrive is international and I can give you the address
of the nearest agent to you if I know where you are. The final drive or
shaft speed for a pug of this size should be about 24 or so RPM.
The vaccum pump for this size mill should pull about 90 plus KPa if you are
using metric guages. I think this converts to about 25 or more inches of
Hg. I have a 8" barrel, 4" nozzle mill that uses a vaccum pump with a 240
volt .75Hp motor.
regards, Craig Martell in Oregon
Hank Murrow on tue 16 may 00
> I have lately gotten involved (as translator, etc.) in building a
>de-airing pugmill from the plans in Harry Davis' book, the Alternative
>Potter.
Be sure to include some sort of cutting screen ahead of the vaccuum chamber
so that the clay coming out of the augers is divided into 'ropes' about
3/8" in diameter for de-airing. A grid of Stainless steel bars 1/16" x 1/2"
forming such a grid will work well. Good Luck! Hank in Eugene
vince pitelka on thu 18 may 00
My Harry Davis mill has a 5 hp single phase 220 volt motor. It may seem
like overkill, but I have never regretted it. It is a 8" barrel, 2"
extrusion. I used a shaft-mounted Falk gear-reducer, which I picked up at a
scrap yard for $40. The arrangement has worked perfectly for 20 years, and
the mill will process a ton per hour. A primary advantage of this
arrangement is that a good-sized shaft-mounted reducer will last
indefinitely, while the motors will eventually wear out, and when they are
separate units it is easy to replace the motor with any one you can pick up
for a good price. If you use an integral gearmotor, you must replace the
motor with the exact matching unit.
For the vacuum I have a 3/4 hp 110 volt motor on a DeLaval centrifugal
vacuum pump from a milking machine, and it easily develops about 26 Hg of
vacuum, which has proved more than adequate. I have always used this mill
in place of wedging, and it has always produce superb clay completely free
of air bubbles.
Regarding the shredder screens which Hank mentioned, I used 1/8"-mesh
18-gauge stainless steel screen from Western Wire in Portland OR, mounted on
a mild steel frame, and have had to replace the screen several times in 20
years, which is of course expected.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
Hank Murrow on fri 19 may 00
>Regarding the shredder screens which Hank mentioned, I used 1/8"-mesh
>18-gauge stainless steel screen from Western Wire in Portland OR, mounted on
>a mild steel frame, and have had to replace the screen several times in 20
>years, which is of course expected.
>Best wishes -
>- Vince
>
>Vince Pitelka
Dear Vince; Thanks for mentioning how you fabbed your shredder screens.
Western Wire is a great resource for other wire products, like the 40, 50,
60, 80, &120 mesh stainless steel cloth we use in our vibrating screens for
sieving glazes and slip clays. Hank in Eugene
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