Re: [ATM] Ain't got no shperometer

["Lawrence D. Lopez" <lopez@mv.mv.com>]

put water on it.
image the sun onto a card.
measure the distance.

ArtfulBodger wrote:
> What's the most accurate way to judge sphericity if you don't have a 
> spherometer?  Is it the Sharpie test?
>
> I'm sorry, thie is probably a FAQ.
>
> I know there are other ways -- reading the bubbles between tool and 
> mirror, judging the feel of the mirror sliding on the tool -- but 
> they seem to need a good bit of experience.  Seems like the Sharpie 
> test is closest to objective.  Or am I wrong, and is there a more 
> precise test that I don't know about?
>
> Gotta make me a spherometer, it's on The List, but my list is as long 
> as yours is....
>
> So.  Sharpie, yes?
>
> Pete
>
>   

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