Hello all, I was just wondering how many reflector glass pushers use a spherometer to determine sphericity of the mirror's surfaces during the grinding stages of a mirror?
Do you feel personally that a spherometer is a necessity to make high quality surfaces, or can someone who uses the standard visual tests (bubble observance, sharpie tests ect,) make as accurate surfaces?
How about the spherometer's use at the end of rough grinding? Is the spherometer the most handy at this point? How much varience would be expected over the surface of the mirror by moving the spherometer across the surface? I have read that if a person used the standard 1/3rd over strokes right from the beginning of the rough grind (in a small 6-8" mirror) then you would have more sphericity, but if you used a chordal stroke at the beginning, then used the 1/3rd stroke at the end of rough grinding , then the spherometer might come in handy to determine if you have enough mirror contact (sphericity), so you could move to fine grinding.
I would think also that once a person in fine grinding removes pits from the previous stage, that sphericity would be at that time somewhat guaranteed? That is if fine grinding started with surfaces with good sphericity from the rough grinding stage.
Comments?
Brien Stratton
Do you feel personally that a spherometer is a necessity to make high quality surfaces, or can someone who uses the standard visual tests (bubble observance, sharpie tests ect,) make as accurate surfaces?
How about the spherometer's use at the end of rough grinding? Is the spherometer the most handy at this point? How much varience would be expected over the surface of the mirror by moving the spherometer across the surface? I have read that if a person used the standard 1/3rd over strokes right from the beginning of the rough grind (in a small 6-8" mirror) then you would have more sphericity, but if you used a chordal stroke at the beginning, then used the 1/3rd stroke at the end of rough grinding , then the spherometer might come in handy to determine if you have enough mirror contact (sphericity), so you could move to fine grinding.
I would think also that once a person in fine grinding removes pits from the previous stage, that sphericity would be at that time somewhat guaranteed? That is if fine grinding started with surfaces with good sphericity from the rough grinding stage.
Comments?
Brien Stratton
