Telescope Making, Rough Grinding a 12.5 inch primary mirror

In this video, I continue the rough grinding of the primary mirror for my Buchroeder Quad Schiefspiegler telescope. I have decided, against the advice of my friend, Dick Parker, to go with a twenty-five pound weight on the back of the mirror. Dick was concerned that I might drop the weight and cause a probelm with the mirror.

Category:

Science & Technology

Tags:

• Rough Grinding
• Socorro
• New Mexico
• astronomy
• physics
• telescope making
• how to make a telescope
• Francis O'Reilly
• Francis J. O'Reilly

[thomasawall]

How many hours with 80 & 120 grit if we are hand grinding a 10" ?

[foreilly1958]

That really depends on how deep the curve will be.

[thomasawall]

About an f5

[foreilly1958]

I remember Rich Combs and Bob Goff making such a mirror at Riverside Telescope Makers Conference in 1995. I think rough grinding (80 Silicon Carbide grit) took somewhere between five and eight hours. 120 Grit, I would go for an hour or so once the curve was roughed in by 80 grit, just to remove the pits from the 80 grit, then on to 220, 320, 500 switching then to Aluminum Oxide 20, 15, 9, 5 and 3 before polishing.

Best regards,

Francis J. O'Reilly

[al022008]

it would be nice if you post a list of materials that you use, so this way is easier to purchase, thanks for this helpfull video

AL

[foreilly1958]

I have been meaning to make just such a video. It is a holiday weekend in the US. This would be a good time to make that video.

Francis J. O'Reilly

[tabhorian]

@MiCompre So true. I find it meditative. But with so many surfaces in these new compound telescopes, I would be tempted to make a machine for it ;)



[MiCompre]

@tabhorian

Telescope Making is usually a hobby . What is a hobby for if not to murder time.

Hand grinding is therapeutic, almost Zen-like. But I am old-fashioned! :) Lol!

[MiCompre]

Francis... You are Russel Porter personified. I bet you spend hours into the night, tucked away in that cellar. Lucky you for having the right kind of space for a grinding room. More power to your elbow my friend. Thanks for this and the best of luck.

MC.

[tabhorian]

You're are doing that manually? I figured by now you would be into the whole grinding machine thing with so many mirrors to grind. Frances, you are ambitious!

[foreilly1958]

Not done yet. It is in New Mexico, I am in New York so I have not had much time to work on the mirror. Hopefully I will get there again by the end of the year to continue grinding.

Francis J. O'Reilly