Im grinding an eight inch mirror with my highschool astronomy club (all five of us!), and we have stummbled across a situation about which our books are rather confusing. when we are grinding the mirror, using a straight across the middle, 1/3 over style stroke, there is only a ring of grit that is actually grinding: that is, there is an air space around the outside and an air bubble in the middle. we have read our guide book ( i cant recall which one) and it is too vauge to be helpful...this, hopefully, is where you come in!!! does anyone know of the correct type of technique to use to fix this problem?!?! any help would be greatly appreciated!

• Re: Donut Mirror - bobmay - April 30, 1999 - 02:43 UTC