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g4yvm
Joined: 01 Nov 2008
Posts: 2
Location: salisbury, UK
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 Posted: Sat Nov 01, 2008 10:39 pm Post subject: Introduction |
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Hi everyone, I am in Salisbury UK and I want to make a Dob. I fancy a 12" one as I already own a 6" reflector but now want something to really blow my socks off!
I've done a fair bit of web reading and have a few questions: why do people go to the trouble of hand grinding their own mirrors? is it just cost??
The Berry book, building a Dob, seems a good book (I havent got it yet) but is it as good as it seems?
Anyone else in Salisbury UK? (with a Dob I mean, obviously there are other people here!!)
david |
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Lawrie
Joined: 25 Sep 2008
Posts: 13
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| Posted: Sun Nov 02, 2008 4:41 pm Post subject: Introduction - 12 in Dob |
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Good Luck with the building of your big dob. It is a big undertaking and if you opt to make your own mirror, doubly so. Getting the figuring right on such a big mirror is difficult and as you may well have to send it away to be aluminised anyway you might just as well consider buying the mirror altogether. Most people do.
I don't know about the Berry book you mention but there are several books on mirror grinding around.
Lawrie |
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bigbry49
Joined: 09 Jan 2008
Posts: 17
Location: Worcester
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| Posted: Mon Nov 03, 2008 2:32 am Post subject: |
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Hi David
Again, best of luck if you decide to build a Dob. I tried in vain to get Richard Berry's book and Waterstones even cancelled my order for it. I think you'll have to send to the States for it if you're really keen.
I built mine from the plans on Ray Cash's website which also mentions the San Francisco Sidewalk Astronomers. A 10" Dob is very heavy made to this design but it's good, nonetheless.
I agree with Lawrie that mirror grinding looks to be a big undertaking but read the November issue of Astronomy Now - Gearheads article which just might spur you on. Mirror blanks &c are available from all over: Galvoptics might be worth looking at.
Also have a look at Tashimi Taki's website for great ideas on telescope making and this then gets you into a whole network of ATMs.
You're standing on the edge of a big black hole!
Incidentally, Lawrie, this might be a factor in your earlier post about this site being moribund. I tried to post a reply to David's post yesterday and hit all the right buttons, as I thought, but nothing registered. Is its difficulty in posting and relying to blame? I can't even find my question about collimation that I posted last week - it was certainly there once. Has it been deleted?
Anyway, best of luck, David
Bryan |
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g4yvm
Joined: 01 Nov 2008
Posts: 2
Location: salisbury, UK
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| Posted: Mon Nov 03, 2008 9:52 am Post subject: |
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Thanks Both.
I cant see myself grinding my own mirror to be honest, its seems an undertaking too far! I really don't have the time for walking around and around ten thousand times.
I'll look at those websites you mention.
David |
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G4LED
Joined: 24 Nov 2006
Posts: 28
Location: Holmfirth UK
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| Posted: Thu Nov 06, 2008 5:34 pm Post subject: Introduction |
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Building your own Dobsonian
David
A useful site worth reading is that of Oldham Optical Co of Scarborough in Yorkshire. http://www.oldham-optical.co.uk
You could have the mirror made to your specification and then collect in person at the delightful resort. Make a long weekend of it, though the distance is daunting. Always plenty to do there and an opportunity to see their seafront astronomical feature set into the pavings I believe.
Of course you could reduce the time scale and invest in the US made Orion Intelliscope, like myself. Mine is the 10" version. Frankly I doubted whether I would have been able to lift the tempting 12" not because of the weight; it is the base size/spread that makes it awkward.
g4led[/b]
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"Holme Valley Weather" Davis Vantage Pro+ station; XT10 Orion Intelliscope(frontspiece) |
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