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

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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


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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


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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!

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!

#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

#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

In article ,
says...
#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

I don't I have summer hols, for the most part of which I'm wondering
what should I do, and is spent staring at my computer screen wandering
aimlessly through the web. Too much time

I had factored in all the cost of aluminising and P+P, and it turns out a
pre-built mirror costs only a tenner or so above it, which is a nice deal
for a 6'' [An 8'' is cheaper to build than buy, by far however!]. Given
the fact that I will probably get errors, or make mistakes, and could
avoid the hassle by buying one, I will prolly buy a 6'' f/8 [Planets
better in this than in the 6'' f/6.7, though the FoV is smaller, right?]

In article ,
says...
#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

I don't I have summer hols, for the most part of which I'm wondering
what should I do, and is spent staring at my computer screen wandering
aimlessly through the web. Too much time

I had factored in all the cost of aluminising and P+P, and it turns out a
pre-built mirror costs only a tenner or so above it, which is a nice deal
for a 6'' [An 8'' is cheaper to build than buy, by far however!]. Given
the fact that I will probably get errors, or make mistakes, and could
avoid the hassle by buying one, I will prolly buy a 6'' f/8 [Planets
better in this than in the 6'' f/6.7, though the FoV is smaller, right?]

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





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