Mirror grinding - Going to give it a go.

Kersh

I have been wanting to do this for ages, so Im going to give it a good shot.

I started investigating it a few months ago, so Im starting to gather the equipment together and get a plan going.

Has anyone on here tried it at all? Either successfully or abandoned?

Ill keep the thread updated on my progress and thoughts if anyone is interested.

Interesting link on it here - http://www.scopemaking.net/mirror/mirror.htm

Gremlin

I've done a couple of mirrors, most recent being a 14" f/3.85 mirror which is currently off being coated. I've almost finished writing up a fairly long tutorial/writeup on the process. I'll try and get a first run of that posted this evening. nMy advice is that for a first mirror, don't be too ambitious. Unless you have something in mind don't go faster than f/6 and dont go bigger than 10" max. Its not that making fast mirrors is particularly difficult, it just takes a LOT more time. I found this guy in germany who supplies me with everything I need.

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

Excellent service and he stocks everything you need.

Don't be afraid of it, its not difficult, but you do need a LOT of patience. That patience is rewarded in bucketloads.

Kersh

Thanks Dave, I was gonna do a 5" or 6".


Was looking at Galvoptics in UK,but your link, and the fact you have used him points me that way


I reckon the reward will be well worth it!

Gremlin

Stephen,

I would suggest in that case 6" f/8. I did contact galvoptics but TBH I got the impression they weren't really interested in supplying ATM's any more. At f/8 you can even (just about) get away with leaving the mirror spherical. AT most it needs minimal correction to produce a superb result. I have a lot of test equipment which you might like to come see. You know where I am.

D.

Gremlin

Another thought. Don't consider going down the route of buying two expensive glass blanks so that you can use one as a tool. Make your tool from dental stone and face it with small 1 inch floor tiles. It works better than plain glass on glass and is considerably less expensive. For dental stone, you can buy it in smallish quantities from a company called rpm supplies in ballymount. They do 5kg bags and 25kg. For a 6" mirror you only need the 5kg and will have lots left over. The tiles I used cost 4euro for a 12" sheet of 1" ceramic tiles. supplier: right price tiles in coolock.

Kersh

Thanks Dave,

I contacted Stathis, Im in the process of getting a 6" blank and grinding set.

Ill organise to drop over to see how its all done over the next few days if it suits.

What did you do with all of the mirrors you did?

Gremlin

Stephen,

I've only done three. My first was an 8" f/6 which went in a scope, the second mirror was a 6" f/8 which I gave away, the 14" is going in a carbon fibre tube and having a corrector added to be used as an astrograph. The 14" took me from Christmas until late March to get finished. When mirrors are that fast they need to be tested by laser interferometry. Again sounds more daunting than it actually is. However anything slower than f/6 is very easy.

I cant wait for you to get started. If possible, Get somewhere setup where you can leave everything so you can go back to it everytime you have some time free.

One of the main benefits of making your own mirror is that you decide how good it will be. For example, you don't have to stop when its commercial grade 1/8 wave. ( which in fact rarely are better than 1/4 wave ). There is nothing to stop you making it better than 1/10 or even 1/20 wave if you want a fine planetary scope.

Kersh

Super stuff, i have an area set aside, and ill have to drop out to you to see the best way to go about making the tools.

I cant wait to get going. Just waiting on invoice off Stathis.

ZeRoY

Best of luck with this Kersh, I have seen some video of mirror making, it looks real interesting and results can be amazing

Kersh

Thanks Zeroy, hopefully it all works out.

The 6" kit should be with me by Friday, and then a visit to Gremlin to get a bit of a heads up :pac:

Looking forward to it.

Rubecula

Good luck Kersh and clear skies.

Kersh

Package arrived on Friday, but only got a chance to open it today

Here are some pics.







Ill have to figure it all out. Time for that visit to Gremlin :pac:

Gremlin

Pop over and we will make a 6" tile tool together and you can start grinding!!!