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mirror blank suppliers in the uk


crashtestdummy
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Give Schott U.K. a ring and ask who can supply your requirements. ( I used to purchase "Suprax" direct from Schott U.K. so they might be able to directly supply your requirements )

"Pyrex" is the brand name of Corning's borosilicate which they stopped making in 2006. Schott purchased Corning's glass line and now makes "Supremax" and "Borofloat" to the same expansion coefficient ( and probably the same formula ) as "Pyrex".

Nigel

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As Peter says. Melting glass is no problem but you can't just pour it into a mould and let it cool as fast as it wants to. You have to melt in the mould and then reduce the oven temperature a bit at a time, and the thicker the glass the longer the job takes. A 20" 2" thick blank could well take weeks to cool sufficiently to be removed from the oven and I am sure that there are few oven owners that would want to tie-up their oven for weeks at a time.

And you would have to make sure that all of the scrap glass you used was the same. "Pyrex" is particularly viscous and doesn't mix well ( that's why there tends to be a lot of bubbles in it ), add that to some ordinary plate and bottle glass and you will never get rid of the stresses induced by the differences in the thermal expansion of the different glasses.

Nigel

Edited by Astrobits
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http://beaconhilltelescopes.org.uk/pricelist.html but I note that this list is dated 2010.

Oldham and Orion produce finished mirrors so presumably have blanks that they might be prepared to sell. If you are interested in plate glass, then many glass suppliers can do water jet cutting, but the price I was quoted locally for a one off float glass blank was more than from Galvoptics.

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Contacted schott who put me in touch with a supplier that uses their supramax material but not heard back yet.waiting to hear from galvoptics about a 450mm borosilicate blank.

I doubt plate glass would survive me grinding it to f4 being only 25mm thick.the boro is 40mm so alot more to work with

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I never seem to have much luck with astro suppliers.when it comes to them answering emails!have heard galvoptics are particularly bad but they wont get my business if they dont reply.

Considering just using 25mm plate glass at the moment.heard that an 18" mirror will be ok if im not too rough

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Still not found a supplier yet.4 suppliers i contacted on the 13th havent got back to me and have re emailed them today.its as if companies dont want business these days!!big grrrrrr

I was surprised to learn from a company 5 years ago that they don't make telescope mirrors any more......it just wasn't worth their while.

Anyway I'm now in a similar position to the OP, not finished my 12" yet and already thinking about a 16!!

nearly as addictive as smoking!!

I can't really help as the only guys I've used are Galvoptics and Oldham, I got a big surprise though when I looked at the jump in price for the thicker low expansion blanks!

Probably I'll end up trying a 16" in the thin plate first, then upgrade the mirror at a later date when I've got around 300 quid to spare!!!

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Beacon Hill say they go to 10", if they could not get the size you want would they say who their supplier is ?

Just realised that the Beacon Hill site has a date of 2010 on it so may be irrelevant.

May sound simplistic but have you rung round a few of the bigger glass merchants in your area?

They may not be able to get anything but they are the people who may know who you could contact.

British Glass if you want to look through the members and try to decide if any could be suitable.

Edited by ronin
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Tbh fella if they cant be bothered to answer emails when its listed as a contact meathod then they arent going to get my business.they do seem to have a bad reputation for not answering emails and tbh that seems to be normal for alot of astro suppliers.i emailed the widescreen centre 2 months ago and im still waiting for them to reply!!

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Considering just using 25mm plate glass at the moment.heard that an 18" mirror will be ok if im not too rough

CTD - 18" x 1" @ F4 using plate glass is definitely doable. It involves a lot more Mirror-on-top grinding and neatness after changing grits as there is not much room to go back and correct mistakes.

One also needs to be more careful about the flatness of the polishing platform compared to a 2" thick pane to avoid astigmatism (I used a 600mm x 600mm x 40mm concrete flagstone I found lying around in my garden, covered in a thin-pile carpet tile). I got my blank from Galvoptics, and found them helpful - always called them though so can't confirm their email response time.

Their glass was good, no bubbles and cut perfectly round. It might be worth the extra effort of ploughing through the poor customer relations to get a decent blank.

Good luck!

Scott

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Have you tried the optical companies like Melles Griot, Optical Surfaces or SLS Optics? I used to deal with these companies for buying laser mirrors and focussing optics before I retired. They all make precision optics for science and technology. But they start off with blanks. Try SLS optics first. I always found them helpful and might be interested to help out. One of the SLS team was at the astronomy show in Warwickshire I recall so they have an interest in astronomy.

http://www.cvimellesgriot.com/

http://www.optisurf.com/

http://www.slsoptics.com/

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I got mine from Stathis Kafalis in Germany and would recommend him anyday, it was a pleasure doing business with him although I know he is not in the UK as you requested.

It looks as though he has 16 and 18 inch borosilicate in stock and larger sizes are upon request.

Maybe worth a shot... http://www.stathis-f...materialeng.htm

Shipping to Belgium for an 8" blank plus grinding material was 15 Euro, I have no idea what a bigger blank may cost to ship to the UK but even at 50eu I'd consider it worth it.

Edited by JB80
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