Mirror testing - NSW?

[torana68 (Roger)]

Hi all ,
Is there anyone in the area of sydney who can test mirrors? I just want to check some I have before I use one of them as a blank (dont want to destroy a good one) all 8".
Roger

[astro744]

A simple Foucault and Ronchi tester is not difficult to construct and if you are thinking of making a mirror, such a tool is a must for regular checks when figuring. There are plenty of links on the web on how to construct a tester. You do not need the micrometer on the Foucault tester if you do not want to quantify the results as a visual inspection of the shadowgram will soon reveal the surface you have and any defects present. All you need is a light source (25W small globe covered by a small box with a 10mm opening to let the light through), a knife edge (Stanley knife razor edge) and a slit (two razor edges or a some aluminium foil with a 5mm slit cut into it sandwiched between a slide mount (no glass). You will also need a mirror holder to hold the mirror vertical when testing. For the Rhonchi test you replace the knife edge with a grating or very very fine wire mesh.

[torana68 (Roger)]

[QUOTE=astro744;658755]A simple Foucault and Ronchi tester is not difficult to construct and if you are thinking of making a mirror, such a tool is a must for regular checks when figuring. QUOTE]

thanks but I have little time to make anything at the moment, just need to see what I have (in case i have a really good one) and maybe later have someone else use one of the pyrex mirrors as a blank. I have looked at making mirrors but the only course I can find in Sydney is nearly $900 and that would be plain silly for me.... (I assume that includes everything to make a telescope, but I have all that a few times over) If anyone does know of a mirror only course in sydney let me know, I might put it on the "todo" list for next year.
Roger

[astro744]

May I suggest the following kit and book from Willmann-Bell:

http://www.willbell.com/ATMSupplies/ATM_Supplies.htm

http://www.willbell.com/tm/tm3.htm

There are many other books but this one is all you need. You don't need a course, just follow the book.

An 8" is not much more difficult than a 6" to construct and I recommend the 8" complete Pyrex kit and the Texereau book since it describes the construction of an 8" f7 mirror.

DO NOT go with 10" or greater as your first mirror unless you have already made a smaller one.

Aluminising can be done at Chi Qin Co.

8" kit, book & one grating + post is less than $330USD. Not sure which grating is best; get both or ask Willmann-Bell. (Postage is expensive due to weight but overall cost is still quite good).

[torana68 (Roger)]

[QUOTE=astro744;659051]May I suggest the following kit and book from Willmann-Bell:

http://www.willbell.com/ATMSupplies/ATM_Supplies.htm

http://www.willbell.com/tm/tm3.htm

There are many other books but this one is all you need. You don't need a course, just follow the book.

nice link that, reasonable prices ... but still need my mirrors tested guess il have to save up and post them to Adelaide.
Roger