Grind your own mirror video

Share practical advice and tips on making your own kit

RE: Grind your own mirror video

Postby Chris Bramley » Tue Aug 09, 2011 4:46 pm

The full 40-minute version of Simon Lang and Terry Pearce's video on how to grind a telescope mirror is now up on our YouTube channel.

You can watch it here: http://www.youtube.com/user/bbcskyatnightmag?feature=mhee

The video covers figuring the mirror blank up to getting it silvered.

To apply the mirrored finish, you could contact Galvoptics at http://www.galvoptics.fsnet.co.uk/ or Vacuum Coatings http://www.scientificmirrors.co.uk/index.html
Chris Bramley
 
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RE: Grind your own mirror video

Postby astrokin » Thu Nov 24, 2011 4:36 am

To get back on to the topic of mirror making, eh-hmm, can I ask all those who have made a mirror and reading this to put something up here. Tell us what you did (precis please or the site will go down) and how you did.

What aperture did you go for, what was the telescope intended to look at, etc.
Post a pic of your telescope or other astro related devices

Sadly ATM is slowly dwindling to the remaining dyed in the wool anoraks (yep and I'm proud).
The Camden Astronomy and Telescope-making Society still survives and anyone within traveling distance of central London who thinks they'd like to have a crack at making their own instrument should contact us.
Email telescopemakers@mulberry.myzen.co.uk

We featured as part of the November '11 Sky at Night (see clip currently on program's site).

S.Allen did you finish? Can we see it?

Let's get our noses to the grindstones!
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RE: Grind your own mirror video

Postby sftonkin » Thu Nov 24, 2011 12:06 pm

[quote]ORIGINAL: Astrokin

To get back on to the topic of mirror making, eh-hmm, can I ask all those who have made a mirror and reading this to put something up here. Tell us what you did (precis please or the site will go down) and how you did.[/quote]

First attempt (1985) was an 8" f/7 -- ended up as f/7.2 -- took about 80 hours (I may still have the log somewhere). Was diffraction limited -- Millies-Lacroix reduction suggested lambda/10. Long since sold and photos lost in one of many subsequent house moves.

Next attempt was a long-focus achromat (112mm f/18). Took ages because I was plagued by wedge and because flint is a sod to polish (I eventually built a polishing machine, I got so fed up with pushing glass.) Too unwieldy -- tried folding it, but introduced astigmatism. Eventually gave it away as a raffle prize about 10 years ago.

[image]http://astunit.com/tonkinsastro/atm/projects/4f_18.jpg[/image]

Helped my 10-yr old son make [url=http://astunit.com/tonkinsastro/atm/projects/timmo.htm]this one[/url] (1996).

I have a 12" f/4.5 that I started 15 years ago, managed to over-correct (owing to a change in the type of Foucault tester I was using), and haven't yet found the inclination to take bake to a sphere and start figuring again. maybe when I completely retire...?

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RE: Grind your own mirror video

Postby astrokin » Thu Nov 24, 2011 11:13 pm

Impressive! To take on a refractor as a first project is brave, and fine looking instrument.
What resources did you use to learn how to do all that?

If you think retirement will provide the time to carry on, think again. I retired and have been busier than ever.
Keep up the good work.

Cheers, Simon.
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RE: Grind your own mirror video

Postby sftonkin » Fri Nov 25, 2011 12:33 pm


[quote]ORIGINAL: Astrokin

Impressive! To take on a refractor as a first project is brave, [/quote]
Indeed it would have been; in fact, it was the 2nd project! (The 8" f/7 was a Newt.) [:D]

[quote]What resources did you use to learn how to do all that?[/quote]

A load of books from Bristol public library. I don't recall all of them, but the original Al Ingalls ATM series was amongst it. For the Newt, I used mostly Howard but had Texereau to hand as well.

[quote]If you think retirement will provide the time to carry on, think again. I retired and have been busier than ever.[/quote]

I'm finding that already now that I'm only working about 20h a week...
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