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Polishing convex maksutov correctors

Started by piekielrl, 12/23/2007 07:55AM
Posted 12/23/2007 07:55AM Opening Post
Is there any easy way to get a steep convex curve on a Maksutov corrector to go MORE CONVEX (by a few fringes) with a polishing tool? I find that even with a long stroke (2/3) COC, the horizontal motion of the tool planes away the center of the glass and keeps flattening it out when I'm actually trying to get it to go more convex. What about putting a lap off to the side and letting it spin? I've has some tries with this, and ended up with zones. Any specific help would be greatly appreciated. Thanks, Bob Piekiel
Posted 12/31/2007 09:44AM #1
Bob, Instead of moving the corrector out over the lap and spinning, can you add just a small amount of eccentric movement to avoid the zoning, experimenting with that "small amount"? Or would it be workable to place the corrector convex side up and polish the outer area with a sub-diameter tool by hand? A few fringes doesn't figure to be a lot of work. You must have a concave test plate to know you are a few fringes too flat? One last comment if you plan on final testing with autocollimation. I once asked a well known Mak maker in the area how to polish and figure the convex side. His answer was to polish the convex side(after getting R as close as possible) and don't worry it. Let it go. It should be very close to a sphere(with proper technique) and any final touch up can be done on the concave side once the scope is assembled. This touch up on the concave side done via autocollimation eliminates the situation your going thru. I really dont know particulars about size of corrector, lap , and R so I hope this may be of some help.