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Questions regarding ATM
#MK wrote:
--- Cheap student, for whom time is not an issue, though cost is! You want to go cheap? OK. Lots of things can be made very cheap or are scroungeable. Mirror-blank: Porthole glass (just make sure it's not hardened glass -- you will *never* get it to figure. Sub-diameter tool for hogging out: Cat-food tin or similar, with "rolled" end, full. Tool for fine-grinding: cast plaster or cement base, with pieces of bathroom tile epoxied on. Use a plaster base for your pitch lap. Grits for hogging out and first stage of fine grinding: Sand. You will need lots of it, but it's free. Grade it yourself. I'd still advise buying finer powders, CeO and pitch. Flat: prism from broken binoculars or similar, or bit of first-surface mirror from photocopier. (CA isn't too bad if the scope is f/8 or above) Timber for building scope and mount: scrounge from skips or building sites. Or you can sometimes get offcuts of large-diameter tubing from agricultural suppliers. The junk corners of 2nd hand chandlers are a treasure trove of stuff for broke ATMs (I was devastated when "Yot Grot" in Lymington closed down!). So is Anchor Surplus in Nottingham (just next to Trent Bridge cricket ground), although they seem to be getting wise to it and the prices are going up. Best, Stephen -- + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books + + (N51.162 E0.995) | http://www.astunit.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + |
#12
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Questions regarding ATM
Err - Stephen Tonkin mumbled something like:
#MK wrote: --- Cheap student, for whom time is not an issue, though cost is! You want to go cheap? OK. Lots of things can be made very cheap or are scroungeable. Mirror-blank: Porthole glass (just make sure it's not hardened glass -- you will *never* get it to figure. Sub-diameter tool for hogging out: Cat-food tin or similar, with "rolled" end, full. Tool for fine-grinding: cast plaster or cement base, with pieces of bathroom tile epoxied on. Use a plaster base for your pitch lap. Grits for hogging out and first stage of fine grinding: Sand. You will need lots of it, but it's free. Grade it yourself. I'd still advise buying finer powders, CeO and pitch. Flat: prism from broken binoculars or similar, or bit of first-surface mirror from photocopier. (CA isn't too bad if the scope is f/8 or above) Timber for building scope and mount: scrounge from skips or building sites. Or you can sometimes get offcuts of large-diameter tubing from agricultural suppliers. The junk corners of 2nd hand chandlers are a treasure trove of stuff for broke ATMs (I was devastated when "Yot Grot" in Lymington closed down!). So is Anchor Surplus in Nottingham (just next to Trent Bridge cricket ground), although they seem to be getting wise to it and the prices are going up. Best, Stephen Failing that, mail me a sensible address and there's some stuff around here you can have *real* cheap... Arthur -- -- 52:30:25N, 1:17:51E http://www.ambermile.co.uk --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.493 / Virus Database: 292 - Release Date: 26/06/2003 |
#13
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Questions regarding ATM
Err - Stephen Tonkin mumbled something like:
#MK wrote: --- Cheap student, for whom time is not an issue, though cost is! You want to go cheap? OK. Lots of things can be made very cheap or are scroungeable. Mirror-blank: Porthole glass (just make sure it's not hardened glass -- you will *never* get it to figure. Sub-diameter tool for hogging out: Cat-food tin or similar, with "rolled" end, full. Tool for fine-grinding: cast plaster or cement base, with pieces of bathroom tile epoxied on. Use a plaster base for your pitch lap. Grits for hogging out and first stage of fine grinding: Sand. You will need lots of it, but it's free. Grade it yourself. I'd still advise buying finer powders, CeO and pitch. Flat: prism from broken binoculars or similar, or bit of first-surface mirror from photocopier. (CA isn't too bad if the scope is f/8 or above) Timber for building scope and mount: scrounge from skips or building sites. Or you can sometimes get offcuts of large-diameter tubing from agricultural suppliers. The junk corners of 2nd hand chandlers are a treasure trove of stuff for broke ATMs (I was devastated when "Yot Grot" in Lymington closed down!). So is Anchor Surplus in Nottingham (just next to Trent Bridge cricket ground), although they seem to be getting wise to it and the prices are going up. Best, Stephen Failing that, mail me a sensible address and there's some stuff around here you can have *real* cheap... Arthur -- -- 52:30:25N, 1:17:51E http://www.ambermile.co.uk --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.493 / Virus Database: 292 - Release Date: 26/06/2003 |
#15
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Questions regarding ATM
In article , says...
#MK wrote: but would you happen to have a suggestion as to where I could obtain primary for under 100 quid? £89: http://www.scsastro.co.uk/it290004.htm £109 (with flat): http://www.galvoptics.fsnet.co.uk/te....htm#parabolic Also monitor: http://www.ukastroads.co.uk Best, Stephen Gosh, much thanks indeed! Quite a nice find, I will probably just buy one of 'em and make the mount, tube etc. by hand Thanks for all the advice, everyone! P.S. It seems that the cost savings pop up at the 8 incher and above side, as I originally calculated that an 8'' f/6 could be made for about £130... give or take a few £10/20, which is quite a saving over the £190 for the 8 incher... but a £99 quid 6'' mirror, compared with it costing about £86 or so quid to make one incl. P+P.... quite nice deal! |
#16
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Questions regarding ATM
#MK wrote in message ...
P.S. It seems that the cost savings pop up at the 8 incher and above side, as I originally calculated that an 8'' f/6 could be made for about £130... give or take a few £10/20, which is quite a saving over the £190 for the 8 incher... but a £99 quid 6'' mirror, compared with it costing about £86 or so quid to make one incl. P+P.... quite nice deal! Cost savings? How do you value your own time? g As a first mirror you would probably be talking about a few weeks worth of intermittent labour. By the time you had a mirror worth coating. Add the cost of the aluminising and those "ready-mades" begin to look very attractive. Making a mirror yourself is something you do to enjoy the task and overcome the challenges. It's not something you do to save money. At least not on the normal, readily available focal ratios anyway. If you start talking about a non-standard mirror then the home made option may be the only way that is remotely affordable. I had a nasty shock only recently. When I asked around the usual (quality) sources for pricing on long focus mirrors. To make an optimised f/10 planetary Newtonian. Let's just say I dropped my plans to buy a finished mirror. Buy an 8" mirror set if you can afford it. Make up a really cheap Dobsonian and begin enjoying the night sky while you save for an equatorial mounting. Or learn to love the Dobsonion. Chris.B |
#17
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Questions regarding ATM
#MK wrote in message ...
P.S. It seems that the cost savings pop up at the 8 incher and above side, as I originally calculated that an 8'' f/6 could be made for about £130... give or take a few £10/20, which is quite a saving over the £190 for the 8 incher... but a £99 quid 6'' mirror, compared with it costing about £86 or so quid to make one incl. P+P.... quite nice deal! Cost savings? How do you value your own time? g As a first mirror you would probably be talking about a few weeks worth of intermittent labour. By the time you had a mirror worth coating. Add the cost of the aluminising and those "ready-mades" begin to look very attractive. Making a mirror yourself is something you do to enjoy the task and overcome the challenges. It's not something you do to save money. At least not on the normal, readily available focal ratios anyway. If you start talking about a non-standard mirror then the home made option may be the only way that is remotely affordable. I had a nasty shock only recently. When I asked around the usual (quality) sources for pricing on long focus mirrors. To make an optimised f/10 planetary Newtonian. Let's just say I dropped my plans to buy a finished mirror. Buy an 8" mirror set if you can afford it. Make up a really cheap Dobsonian and begin enjoying the night sky while you save for an equatorial mounting. Or learn to love the Dobsonion. Chris.B |
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Questions regarding ATM
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Questions regarding ATM
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#20
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Questions regarding ATM
http://www.dhinds.co.uk/frames.html
6" mirror £40 in "for sale- used products" Colin Smith Somerset Telephone: 01458 440366 E-Mail: Mobile No: 07860 825942 Price: £ 40 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.496 / Virus Database: 295 - Release Date: 03/07/2003 |
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