glass discs?

I've been trying to find a source of clear glass discs, around 35mm diameter and preferably 1.5 mm thick (though 2mm is OK). They are for the windows in
optical toys so don't need to be of high optical quality. A local glass firm made some for me with a diamond core drill, but they are not very good - loads of chipping round the edges. A friendly glassblower did a much better job but I can't call in that favour too often. It's not so difficult to find precision optical windows at a price but I don't need that sort of quality. Google has turned up nothing, but there must be a supplier out there as commercial kits for e.g. kaleidoscopes have three in them.
Hopefully the collective wisdom of the groups may have an idea of a source? I only need about a dozen. All suggestions gratefully received.
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Norman Billingham wrote:

Must they be glass Norman?
polycarbonate or perspex perhaps?
Bob
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"Norman Billingham" <norman.at.tumulus.org.uk> wrote in message

find some 35mm diamiter glasses, as in the type you drink out of, and remove the tall portion leaving just the base?
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"Norman Billingham" <norman.at.tumulus.org.uk> wrote in message

Any cheap torches available ?
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On 4 Dec, 23:11, "Norman Billingham" <norman.at.tumulus.org.uk> wrote:

i remember about three years ago when looking for glass disks for my waste oil burner .. the local glass guy showed me a card with samples on ..
these were about the diameter you want .. and if i can remember they had pilkington written on the card.
they were not big enough for my use ..i ended up buying candle thingies from woolworths.
if you want a lot of them ..then a trip to St-Asaph business park North Wales maybe will yield results.......thats were the UK optical industry is, including specialist branches of pilkington and many other optical companies.
Lot of top secret stuff goes on there ..so don't be expect to get past the gates at a few of the companies.
all the best.markj
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On Fri, 4 Dec 2009 23:11:09 -0000, "Norman Billingham" <norman.at.tumulus.org.uk> wrote:>I've been trying to find a source of clear glass discs, around 35mm diameter

You don't say what sort of quantities you are looking for.
After getting similar results from a local glass firm (problem in my case was they were far too thick), I got a diamond core drill a bit bigger than I needed and cut two disks from a sheet of glass. Then I clamped each between two mandrels on the lathe with double sided tape for retention and a rotating tailstock centre for pre-load. Then I used a diamond hone and water to grind the diameters and edges down to what I needed. These were for 3/4" diameter disks for oil sight glasses. The 2mm glass came from a picture frame in the workshop that I'd accidentally smashed when moving it :-(
It took less time to cut and grind the glass than it had to go to the glass shop and negotiate for a handful of cores!
Mark Rand RTFM
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Norman Billingham wrote:

If you only need a dozen, could you not pay him to make them for you?

Other options would include an "ordinary" glass merchant of the type that does glass cut to size. They can usually do round windows, clock glasses etc, and hence may be able to do small sizes.
If that fails how about cutting your own? A wet tile cutter may do the trick. Alternatively a good diamond glass cutter with a trammel to make your scored circle, then a few radial cuts away from it before tapping or heating/cooling to snap off the segments.
Another option might be to cut a polygon with straight edges just a bit over size and then grind it down to the final fit using a carborundum stone.
--
Cheers,

John.

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I tried cutting glass on my wet tile cutter. It did cut, but chipped quite badly. I assumed any glazier could make them though.
NT
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wrote: <big snip>
I tried cutting glass on my wet tile cutter. It did cut, but chipped quite badly. I assumed any glazier could make them though.
NT
OK, time for me to but in! Amateur telescope makes do this all the time! First, never try to just do one piece of glass, you need a stack. The outer pieces should be discarded. One good way is to embed the stack of glass in plaster of paris. No need for a diamond hole saw, a simple cutter can be made from sheet metal, formed into a tube. You will need some slits in it. The actual cutting media is carborundum grains obtainable from lapidary/rockhound shops, or amateur telescope maker suppliers. Use ordinary plasticine to form a dam around the area the cutter will enter. Make slurry of carbo and water, and run the cutter slowly, with gentle downward pressure. You will have a stack of glass disks in no time. The outer ones will be chipped a bit, the inner ones should be near perfect.
Steve R.
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On Fri, 4 Dec 2009 23:11:09 -0000, "Norman Billingham" <norman.at.tumulus.org.uk> wrote:>I've been trying to find a source of clear glass discs, around 35mm diameter

Does it need to be glass? It would seem an ideal application for acrylic sheet, such as Perspex.
For example: http://www.wickes.co.uk/Acrylic-Sheet/invt/210001
It has a protective film both sides which should be left on until you have finished shaping it.
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HI Norman
Norman Billingham wrote:

If you are prepared to make them yourself then a diamond core drill in a drill press will do the job - you'll want to drill slowly and with lots of water to cool the work. If the ones you had were chipped then they were either drilled too fast, without adequate cooling or the core drill was worn out...
To buy off the shelf - you want to talk to people who supply material for glass fusing (jewellery - that sort of thing)
One supplier is Delphi Glass - they are in the USA and have 'micro-thin 1.25" glass circles'(don;t know how thing that would be but you could ask them..
http://www.delphiglass.com/index.cfm?page=itemView&itemsysid 6682
How flat / edge-smooth do they need to be ? Another way would be to cut the circles using a lens cutter or a proprietary 'turntable' cutter, and then either grind the edges to smooth or give them a light fuse in a kiln...
I made something similar as filters for some led lamps for somebody recently - they were in pale yellow- but clear would be just as easy....
Drop me an email if you'd like to chat about it ( snipped-for-privacy@inspired-glass.com). I'm in Ireland - but postage shouldn't be too much of a problem..
Adrian
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"Norman Billingham" <norman.at.tumulus.org.uk> wrote in message

diameter
windows in

glass
very
did a much

difficult
sort of

out
source?
Norman,
Relatively easy to cut them yourself. Turn up a copper 'tube' with an inside diameter of the required disk. Mount in vertical mill, place glass sheet on cardboad and secure. Build a dam of putty or plastecene where the hole is needed, fill with light oil. Lower copper tube at low revs into oil having charged the copper with carborundum powder (valve grinding paste). You need to use hand quill feed or a light spring so as not to press too hard. Suprising how quickly it cuts.
BUT - if they are for toys is plain glass good enough - should it not be toughened or perhaps polycarbonate?
AWEM
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Andrew Mawson wrote:

Interesting that, but can you get 35mm copper tube?
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
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The Medway Handyman wrote:

Andrew said "turn up a copper tube" ie on a lathe.
Bob
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On 05/12/09 09:57, The Medway Handyman wrote:

Yes, copper tubes go a long way above the 15, 22, 28mm sizes used domestically ... 35, 42, 54, 67, 76, 108, 133, 159 and 219mm are available.
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Andy Burns wrote:

Ah. Didn't know that - thanks.
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
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On Fri, 04 Dec 2009 23:11:09 +0000, Norman Billingham wrote:

<snip>
Are you allowed to use glass in toys at all nowadays?
--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
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On Dec 4, 11:11pm, "Norman Billingham" <norman.at.tumulus.org.uk> wrote:

How about trying your local welders suppliers , we used to wear cutting goggles with replaceable clear glass lenses ?
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OH! One more thing, make sure that you do not use tempered glass! It will shatter into tiny pieces!
Steve R.
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Norman Billingham wrote:

<snip>
Clockmakers' suppliers Meadows and Passmore list 2mm flat glass rounds, and will do special sizes for orders of 10 or more. www.m-p.co.uk
Tempus, in Exmouth, do very clever stuff with glass - bevelled edges, fitting to bezels, and so on, as well as flat circles. No web site, so 01395 270058.
You're looking at over 3 quid each for either of those places.
--
Kevin Poole
****Use current date to reply (e.g. snipped-for-privacy@mainbeam.co.uk)****
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