Richard Mahaffey on sat 9 jul 05
Helen,
They did not tell us during our visit to Gladding McBean why they only
turned the long insulators, or if they did my hearing disability
prevented me from hearing it in the noisy shop.
They did use a mold and arm that "screwed it's way into the clay on the
mold to make those insulators that look like upside down bowls with an
owl's head on top. Those are made to screw on to a wooden screw.
The underside of the mold was pushed into the clay sitting on the mold.
as it went down it turned at the appropriate number of revolutions for
the speed of the descent so that the threads came out perfect. I
believe that the thread from was a buttress thread. They put a mold on
the table and as the underside (when it use) form started to come down
they used some kind of lube - looked suspiciously like olive oil -
perhaps it was motor oil was brushed on the form before it plunged into
the clay. as the arm retracted the underside from it spun in the
opposite direction so as to unscrew the form from the clay insulator.
Those insulators were glazed with what looked like an Albany Slip
glaze, you know crock brown.
I hope that you get the idea from my description.
Rick
Helen Bates on mon 11 jul 05
Hi Rick,
Thanks for the description.
I am thinking that the mold was on the table with an outside thread pointing
up. The clay was placed on top of that, then the arm with a convex piece at
its end came down over the clay on the mold and the mold rotated to form the
inside thread of the insulator. Or maybe I've got it completely backward or
inside-out...
It took me a few minutes but I did find out what a buttress thread was.
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Helen
Belleville, ON
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