Re: [ATM] Book Review.... sort of

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

I have tried a couple of times to follow their advice on figuring, without success, so far.
Guy

Jerry <wa4guu@verizon.net> wrote:"A Manual for Amateur Telescope Makers" by Karine and
Jean-Marc Lecleire and of course published By Willmann-Bell.

This brings me to the new book "A Manual for Amateur Telescope
Makers".  I don't like to be negative, so I will ask a question or two.  Has
anyone used the figuring techniques in this book to successfully figure a mirror?  If you did, did you find any of those methods to be wrong?  Of
course you can tell I have a negative view of some of the figuring
techniques I see in there. I use some of those techniques but not for what they do. And since I have used them for other reasons, I think I have a grasp of what they would do.  I don't think they will do what the book says they do.

I have never seen any defect that required a figure 8 stroke to fix. With
ease, I have used straight strokes to fix anything. In one place working for a half hour on a raised zone is recommended with no concern shown for the magnitude of the defect. And I see where pressure is put on the wrong side of the lap. I know that with a raised edge you have a choice of wearing the high edge to the longer radius inside of it, or wearing what is inside it to the shorter radius of the raised edge. The method described in the book would have to be directed more specifically than stated.

I will be sure to try these methods as presented in the book on my next
mirror to see if I can force them to work as described.  Until I see them
actually work, from my experience I would have to say this is a serious step backward from Jean Texereau's book.

I make no claim of being an expert. My opinion is based on my experience, more than some and less than others. I am interested what other mirror makers think of the figuring methods in these books.



Guy  Brandenburg
Washington, DC
My home page:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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