availability of oow expansion glass

[Vlad]

What availability? Years ago ( about 15) I could get off the shelf low expansion glass from several locations. Now I've been trying for weeks and I get no replies whatsoever. Anybody got an idea where I can get this stuff from? I need a 20cm disc to make a mirror. It's got to be low expansion.

Thanks

phil

[barkis]

Vlad, I think I may have a Pyrex one, but it has been used to grind a mirror, and still has the Optical pitch adhered to it. It depends what thickness you require. I also have a new 6" Pyrex disc.

You could try Oldham Optical too.

Ron.

[jgs001]

Vlad, I can't help with the glass, but if you click edit on your first post, then click go advanced, you can edit the title, no need for second posts.

[Vlad]

Thanks JGS, my first post was bound to mess up.

Barkis,

[Vlad]

Barkis, thanks for the offer, it's just what I need. Let me know how much and I'll get it to you.

Cheers

Phil

[barkis]

Barkis, thanks for the offer, it's just what I need. Let me know how much and I'll get it to you.

Cheers

Phil

Give me a little time to clean off the old lap, and I will inspect it for bubbles. I wouldn't want you to break into one at a critical time and spoil the mirror.

I take it you mean the 8" disc is the one you want.?

Ron.

[barkis]

Phil, I have cleaned the pitch off the blank. It is Pyrex, and it is

210mm in diameter, and 27mm thick.

It has been used to grind a blank intended as an optical flat, so the ground side is plat, but the squares are ground into the glass itself. Probably a millimetre deep. You can grind them out if you wanted that side to be the mirror surface, or I recommend using the reverse side which is fine. There is a small piece out of the edge on the good side, but by the time you chamfer the edge it won't impinge on the optical surface.

I have attached a couple of pictures. let me know what yoiu think.

Ron.

[Vlad]

That looks great Ron. 210 mm is ideal. I have a complete Maksutov lens at 200 clear aperture, so the extra 10 mm will be useful in capturing the full field. The squares will be generated out, and the curve made on the best side. The opposite side will be curved convex to thin out the edges. You should see my generator, Heath Robinson has nothing on me!

Phil

[Vlad]

£25 is fine by me! Thank you. Where do I send the cheque, unless you take paypal, that's easier. How do I send personal email to give you my address?

Thanks again,

Phil

[barkis]

£25 is fine by me! Thank you. Where do I send the cheque, unless you take paypal, that's easier. How do I send personal email to give you my address?

Thanks again,

Phil

I will send you a PM with my Paypal info.Phil.

Ron.

[Vlad]

Thanks Ron. Paypal is quicker and better than snailmail. Also more convenient. I haven't got a stamp or your address, so it's just as well!!

Best wishes,

Phil

[Vlad]

Thank you Ron,

I will pay by Paypal as soon as I get details.

Kind regards,

Phil

[Vlad]

Barkis! need your Paypal details to send you some Money!

Thanks:confused:

Phil

[barkis]

You have paid by Paypal Phil. I sent a confirmation to you by PM, Also, the parcel was posted to you on Saturday Morning, but being a Bank Holiday Weekend, there could be a delay in delivery.

Cheers.

Ron.

[Vlad]

Already paid, eh?

My memory isn't what it was. Maybe I should have myself checked over with the vet.

Thanks,

Phil:confused::)

[Vlad]

The glass arived this AM, safely. Thank you, now I can get on with the Cass.

Phil

[barkis]

Thanks Phil.

I hope you will keep me posted on your progress with this project.

Ron.