Parabolizing a 20" Mirror, Part 2: Deepening the Curve

The curve on the 20" quartz telescope mirror needs to be deepened from a roughly spherical surface toward parabolic. Gordon Waite shows how to use 7", 8" and 12.5" pitch laps to rough in the paraboloid. Gordon performs pitch lap polishing by hand on a powered turntable.

Category:

Science & Technology

Tags:

• polishing a mirror
• atm
• amateur telescope making
• mirror making
• mirror grinding
• figuring a mirror
• figuring
• parabolizing
• pitch lap
• polishing

[spilperson]

Gordon,

Thanks for the excellent videos, you have been reading my mind as to what I wanted to see. A couple of questions if you don't mind:

1. What kind of abrasive are you using here, and are you doing anything special to keep it wet? I never saw you spray any water, but maybe that was just off camera.

2. Have you ever done anything to quantify how much glass you take off at what rate with the different laps, strokes, pressures, etc?

Thanks again, and please keep them coming.

Frank S

[vipond50]

Hi Gordon

Wow.... what excellent information you have provided... as usual !

Thanks for taking the time to do these videos and I look forward fpr more.

Are work the F3.5 on Cloudynights Forum? Man that thread was awesome!!!

Al l my best

Bill