A Semi Rimless frame is made with one part metal or plastic rim and one part nylon cord.
The cord is usually at the bottom of the frame, but can be at the top or temple edges.
A groove approximately 0.8mm deep and wide is cut into the edge of the lens and the nylon cord is stretched around it, holding the lens in place securely.
The lens has to be made with a minimum edge thickness of 2.00 mm at the thinnest grooved edge when it is cut to size, a 0.80 mm trench to hold the cord and 0.60 mm of lens material each side of the trench for strength.
It is physically possible to reduce the edge thickness at the thinnest grooved edge to 1.50 mm but it is not advisable as the lens material on either side of the trench will then be only 0.35 mm, thus making chipping or splitting more likely.
| Semi Rimless with cord at bottom edge. |
Semi Rimless with cord at temple edge. |
Semi Rimless cord detail, we have coloured |
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the nylon cord pink to show it clearer. |
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