The use of the high-base bevel depends on two parameters: the frame and the lens.
• Concerning the lens, the main constraint is the thickness of the nasal and temporal edges.
• Concerning the frame, the crucial elements are the bridge and shape of the groove. The hinge is an
additional factor in the case of a metal frame, the arms for a plastic frame.
For this job, the lens base must always match the frame base perfectly. Too great a difference
between the two could be detrimental to the quality of your job.
Cross-sectional view of a high-base bevel
1: Shelf bevel value
2: Width of the flat side of the bevel
3. Front surface tracking value
a. Captioned screens
1. High-base bevel “front surface tracking” screen
2. Work area
Image of the shape to be edged:
Frame shape at bottom of groove
Bevel trajectory on rear surface
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