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Posts Made By: Douglas Hudgins

May 28, 2007 12:23 PM Forum: Telescope Making

Acceptable wedge?

Posted By Douglas Hudgins

Hi Everyone:

I'm working on a 32" f/5 BVC mirror. Right now, my focus is on getting the back of the blank prepared so as to minimize the chances of developing astigmatism as I grind and polish the face. The back has already seen a very coarse degree of flattening--it is my understanding that BVC blanks are pregenerated by slumping on a mold, and that afterwards, the convex back side is ground (very roughly) flat. I want to clean up the back side by grinding it flat through #220.

All of that is no problem. My question is about wedge--specifically, how much wedge is acceptable in a blank of this size? Using a caliper, I find that there is about 0.015" difference between the thickest and thinnest points around the edge of the blank. Is 0.015" of wedge across a 32" blank acceptable, or should I be trying to cut down this wedge before grinding the back of the blank flat?

Thanks for any advice.

Doug Hudgins
Dumfries, VA

May 13, 2007 11:38 AM Forum: Telescope Making

What Do Amateurs Do For a Living?

Posted By Douglas Hudgins

I'm a space scientist working for NASA. Started in laboratory astrophysics research in 1991 at NASA Ames Research Center near San Jose, CA. Now working as program scientist for the Spitzer Space Telescope and Herschel Space Observatory at NASA Headquarters in Washington, DC.

My interest in amateur astronomy and ATMing goes back to my high school days in Wyandotte, MI, though.

Doug Hudgins
Dumfries, VA
ATM Truss-tube Dob w/24" f/5 Swayze primary
Meade LX200 7" Mak