Pulley-and-former mechanism for shaping a concave surface
Twelve pulleys on pyramidal screws serving formers of various curvatures
A curved former (centina) studded with rollers is drawn to guide a shaping template: the piece a b must be fitted to an equal concavity by the template n, whose guide c d rests on the pulleys that steer its correct curved motion, the shaped piece being drawn taut like a sheet against the tool. A corner note explains that twelve pulleys fixed to pyramidal screws are a convenience because the same pulleys can serve the different curvatures of various formers. A small press sketch below carries a firing note about glass impressed hot and reheated, or copper fired together with its regulated varnish.
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Template guided on pulleys along a former
a b is the piece whose concavity must be fitted to an equal concavity by the template n, and must be set with firmness. c d is a guide of the template n which, with its uniform concavity, rests on the pulleys that steer its correct curved motion; e f is the former where the pulleys are fixed. The shaped piece must be drawn taut, like a sheet, against the shaping tool.
Twelve pulleys on pyramidal screws for various formers
These 12 pulleys below are fixed to pyramidal screws, and from this a convenience arises: the same pulleys serve for the different curvatures of various formers.
Firing note: glass and copper with regulated varnish
Glass impressed hot and reheated; or else copper fired together with its regulated varnish. The note accompanies a small sketch of a press at the foot of the leaf.