Mirror making supplies

[Guest]

I have a 8.5 inch mirror blank which I started grinding 50 years ago. It was never finished because life got in the way but I kept hold of it. I got to the point of polishing but I suspect it has a turned down edge. I still have the book by N E Howard about amateur telescope making.

I've noticed several posts about mirror making and it got me thinking about having another go. I see that almost all of the suppliers of grinding/polishing powders, pitch etc I used at the time no longer exist so I wondered where people got their mirror making supplies from these days.

I'm in Shropshire UK by the way.

Cheers

Steve

 

[mapstar]

Hi Steve,

Most of my grinding/polishing medium came from a popular auction site using Minerals-Water.ltd for carbide down to 400grit.

600 alu oxide is a lot harder to find in good quality. Lapmaster is about the only place I can think of for this for an optical quality source? but you'd have to contact them to verify cost/quantity 

1200 cerium oxide I ordered direct from a company called glasspolishltd you need the fine optical grade. 

Someone else will probably pop along with a few more suggestions but I hope this helps 

[Guest]

Thanks Mapstar,

Where do get pitch from?  Do you still use pitch for polishing?

I still have the glass tool as well as the mirror.

Steve

 

[cassiewoofer]

Blimey!!! 50 years in the making that must be some sort of record.

I started making mirrors 2 years ago and got most of my stuff from Galvoptics. Still use pitch / and make pitch laps...... one of the challenging and frustrating part of the whole process. I learnt last year that polishing needs to be done during the summer months.... the pitch just doesn't behave when it's cold enough fro gloves...

 

Good luck with it.

[mapstar]

Forgot about the pitch sorry.

Galvoptics is a source if they have any.

I got mine on a mirror making course run by John Nichol. Gugolz 55 which is a little softer.

It is difficult to find in this country. Lap master may supply some to you.

[Paladin]

Hi Steve,

I’m afraid I can’t give you any information on present day mirror supplies, but thought I would post, as your mirror making history nearly echoes that of my own.  I constructed my first telescope, a 6 inch f8 Newtonian, when I was a teenager in the mid-nineteen-fifties. I had to save up the money from my holiday job to buy the mirror assembly from Brunnings of High Holborn in London for £5.0s.0d!  I constructed the scope and mounting out of wood, but did not make a very good job of it, as it did not perform as well as I had hoped, so I soon lost interest and eventually sold the mirror to a friend.  I recently found an old photo of my 1^st scope, circa 1956.

In 1962, when I was in my early twenties, I saw the Handbook for Telescope Making by N E Howard in a bookseller’s window, and bought it after a quick look-through re-kindled my interest in telescope making.   As Howard’s book describes the grinding and polishing of an 8 inch f7 mirror, another trip to Brunnings was necessary to purchase a mirror-making kit.  After a while, I managed to rough grind the mirror to f7, but like you, other time-consuming activities came along which left little time to complete it, so the project was put on the back burner.  I did finally construct another telescope, which was finished last year; for which I used a readymade mirror. The original mirror and tool are still in the same state in the loft, 54 years later. Unfortunately, it’s unlikely to be finished now, as I’m the process of considerably down-sizing to such an extent, that not only the mirror project but also my newly made Dobsonian might have to find another home.

 Sorry for hi-jacking your thread; but keep us posted about your progress and good luck with the project.

 Paul

 https://stargazerslounge.com/topic/255887-8-inch-dob-finished-at-last/

[Guest]

Thanks everyone and especially to Paul for his pictures,

I bought my mirror kit from Brunnings in the 60's sometime. As well as the blank and the tool I still have a jar of 80 carborundum from them. For a year or so I had a 45 gallon oil drum full of water in my bedroom. The mirror was ground and I made a button lap using a mould made from a sheet of thick rubber and the mirror was polished. I also made a Foucault tester but I came to the conclusion that the mirror had a turned down edge and I would have to go back to fine grinding. After that it was A levels, university etc etc  add that was that. Now I'm retired and returning to my hobby.

There seems to be a very energetic amateur telescope making movement in the US. One site I've looked at is called Stellafane and in fact I've downloaded their designs for a Foucaullt tester.

Thanks again to everyone. I'll be in touch.

Steve

 

[Ajohn]

You can get pitch from Walsh. A reliable source told me that this can be used but I haven't used it yet.

https://www.hswalsh.com/product/pitch-embossing-cement-black-tp57

It looks to be cheaper here

https://www.goldschmiedebedarf.de/product_info.php?products_id=8096

Also from here along with the grits, blanks etc

http://www.stathis-firstlight.de/spiegelschleifen/materialeng.htm

 When I contacted him about pitch he offered a softer grade than he usually sells as I am in the UK. Not sure about that as soft can help obtain turned edges according to some but hard can mean sleeks. If it's too hard it can be softened with real turps - but don't try white spirits like I did once.  It works after a fashion but it tends to come to the surface of the lap. I believe the German supplier suggests vegi oil. Turps can be boiled off if too much is added. Oil ??????  I doubt it.

John

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[Merlin]

There's also www.scientificmirrors.co.uk for mirror-making materials.

[morayskies]

On 22/02/2016 at 16:27, woodblock said:

Thanks everyone and especially to Paul for his pictures,

I bought my mirror kit from Brunnings in the 60's sometime. As well as the blank and the tool I still have a jar of 80 carborundum from them. For a year or so I had a 45 gallon oil drum full of water in my bedroom. The mirror was ground and I made a button lap using a mould made from a sheet of thick rubber and the mirror was polished. I also made a Foucault tester but I came to the conclusion that the mirror had a turned down edge and I would have to go back to fine grinding. After that it was A levels, university etc etc  add that was that. Now I'm retired and returning to my hobby.

There seems to be a very energetic amateur telescope making movement in the US. One site I've looked at is called Stellafane and in fact I've downloaded their designs for a Foucaullt tester.

Thanks again to everyone. I'll be in touch.

Steve

 

I still have a 6" f8 mirror made by Brunnings. If memory serves it's etched with October 1958. Damn fine mirror nit doing a lot just now though :-)