Hand Edging Special Considerations Flashcards
What are the 4 reasons to hand edge?
-Smooth edge surfaces
-Remove sharp edges from a lens after it has been machine edged
-Reduce lens size
-Reshape
How do you remove chips using a hand edger?
steepen the rear bevel angle in the area of the chip to grind away chips
How do you salvage an off-axis lens with a hand edger?
modification of the lens shape-especially lenses with distinct corners to not disturb appearance of frame
How do you correct for unwanted vertical prism using a hand edger?
Removal of extra lens material above from top or bottom of
lens to move MRP relative to frame
What are the different ways a lens edge can be polished? 4
-In-edger polishing
-Rag Wheel
-Drum Tool
-Polishing Machine
Explain in-edger polishing. 2
-A wheel inside an edging machine which has the ability to give lens edges a high luster
-Amount of polish can vary depending on age of the wheel
Explain a Rag wheel for polishing edges.
Lens edge is buffed by hand on a rag wheel using buffing compound
Explain a drum tool used for polishing edges.
-Lens edge is buffed by hand using a flat rotating drum tool with a felt surface where buffing compound is applied
Explain a polishing machine. 2
-An automatic machine where lenses are placed after edging
-Lenses are not deblocked before using this machine
What 4 considerations need to be made when re-edging for a different frame?
-Distance between optical centers needs to remain the same
-Lenses must be large enough
-Rotating the old lens so it fits the new frame may not work
-Glass lenses need to be re-hardened
What should we consider when cleaning glass lenses? 3
-Non-water-soluble markings can be removed with a solvent or alcohol
-Detergent or lens cleaner can be used
-Small spots can be removed using the point of a lead pencil
What should we consider when cleaning plastic lenses? 3
-Acetone can be used but should not
contact plastic frame parts
-Detergent or lens cleaner can be used
-Ultrasonic bath can be used but not on lenses with antireflective coatings
What should we consider when cleaning polycarbonate lenses? 3
-Mild, non-citrus based dishwashing detergent is recommended
-alcohols will work but are considered a secondary option
-Do NOT use methylene chloride, methyl ethyl ketone or any
of the ketone family, acetone, or chlorinated/aromatic hydrocarbons
What are the basic rules for hand edging?
-keep the angle between the hand edger and the lens consistent
-listen to the wheel
-travel as far around the bevel as possible without lifting the lens away
Explain how to make the most of the blemished sphere lens blank. 2
-same power can be rotated around the OC
-same power all over the lens