Back to Home

ATM Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Amateur Telescope Making | Post

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Polishing Query

Forum List | Follow Ups | Post Message | Back to Thread Topics
Posted by Ian McKernan on July 18, 2002 08:07:59 UTC

Hi all!
Ive now got my 10 inch pretty much polished, (at least the surface looks good!), but it has a funny shape. I put it on the Ronchi tester at our group session last night and after everyone had a look the main reaction was, "How the hell did you get something that looks like that!!!" The shape of the bands was likened to an "impact structure". I will either have to fix this or endure the good natured ribbing of friends forever!

Anyhow, ive done some more polishing on pitch, MOT and been playing around with "RonchiZ".

Ive managed to draw a profile in this program that gives me a good simulation of what i'm seeing through the tester at the moment.

That profile has a turned up edge, with a raised ridge about 40% out from centre surrounding a central depression.

From the shape of the profile i think that if i get rid of the ridge the hole in the centre won't look so daunting, and the turned up edge i'll get rid of in parabolising. I just want to get a sphere for now. this is complicated by the fact that my glass is pretty thin. I started with 19mm, but after grinding, its now 16mm at the edge.

I'm planning on continuing MOT, with very short W strokes to take it to a sphere. Any advice or opinion about how i might have gotten this shape in the first place would be appreciated.

Follow Ups:

Login to Post
Additional Information
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2023 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins