Lens Support - Weco cad III Operation Manual

3.5 Lens support

The lens is positioned on 3 pins which
forms an equilateral triangle on a
cardanic ring.
The transparent supporting plate is hold
in place by three rubber supports
opposite to the caps of the pins S. After
lifting the supporting plate you can
position the lens between the pins and
the supporting plate. When you release
the plate the lens is pressed onto the pins
which will adapt to the back curve of the
lens by use of cardanic bearings.
Independent of the lens surface, the
decentration point will always be in a
vertical position in relation to the axis that
goes through the middle of the blocking
device and the block.
Abb. 5
This geometrical setting ensures that:
• During the blocking process only
vertical pressure is applied to the lens
which avoids unwanted shifting.
• The block and blockpad make full
contact with the lens surface.
• The position of the lens in the blocker
and the edger is identical.
As shown in ill. 5; is the adaptation of the
pins to the back curve of the lens
particulary important for those corrections
that have a high prismatic effect in the
blocking point.
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