Re: [ATM] Curious

["Neil Booker" <neil@astronomy.ndo.co.uk>]

Hi Francis

> Neil,
>
> Thank you for watching my videos!
>
> My question to you is how have your two mirrors turned out?

Well they're round and concave. First attempt was a six inch F10. Got the
kit (blank, tool, grits etc.) then said what's first? Bevelling the edge. So
put a bit of a bevel on blank and tool and asked what's next? Hogging out.
So started hogging out only to look down and see that the supplier had
bevelled the other side of the blank and the tool already. Things haven't
improved much since then. I couldn't get the hang of the Foulcault test at
all so when it looked a bit like the diagrams I thought 'stuff it' that's
near enough. I now know that's was wrong and have since learned, from here,
that at F10 once you can see the shadows you've gone too far.

Second attempt is a six inch F5 (because I'd heard that the shadows were
easier to see in a short focus mirror), using the tool from the previous
mirror as the blank, that came out F5.5 as I got confused as to the number
of inches in half a foot (no I'm not sure how I managed that either) Got the
hang of the Foulcault test though but couldn't get rid of the TDE (maybe
third time lucky). Haven't managed to get the time and the inclination to
coincide and finish the latest scope so haven't used it in anger yet.

> You might consider joining a mirror making group.

Have done but cant find any near by. Heard of one three hundred miles away
in north London.

> Stellfane has a list of
> worldwide mirror making groups at their website, www.stellafane.org look
on
> the webpage for the mirror making class.

Thanks I'll have a look at that.

Neil

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