Rough Grinding a 20" Quartz Telescope Mirror on the Fixed-Post Machine

This video shows how to setup a mirror grinding machine for fixed-post grinding, also known as spin grinding or spinning. After setup, you'll see how abrasive and water are applied, and how the grinding action is driven. Then the swarf or sludge is removed from the still-running machine and the cycle is repeated. This demonstration uses #120 silicon carbide for grinding this quartz mirror.

Category:

Science & Technology

Tags:

• mirror
• newtonian
• mirror grinding
• amateur telescope making
• fixed post grinding
• spin grinding
• spinning
• rough grinding
• telescope making
• atm
• mirror making

[ThomasCoding]

Can you set videos title like part 1, part2, etc. It will be usefull to navigave between videos.

[GordonWaite]

Thanks! I'll try to get things retitled. Appreciate the suggestion... Gordon

[GordonWaite]

I finally got all of the videos renamed. Let me know if this way is better for you. Thanks again for the suggestion! Gordon

[ThomasCoding]

@GordonWaite Thanks a lot. By the way interesting machine ;) I have made my first mirror by hands. I think in the future to build something like this for grinding and polishing the second mirror. The first mirror was 6 inches with spherical surface. Have you any information about grinding and polishing process with this machine? How do you know that you must shift the mirror out of the edge on 2.5 inches?

[GordonWaite]

@ThomasCoding The overhang of the tool is kind of something you learn from experience. As a rule of thumb, you can overhang about 15% of the diameter of the tool as a good starting point. Moving it in should deepen, moving it out should flatten. It's a place to start, at least... Thanks!

[TalksWithDirt]

It looks like you'll wear through your tile tool pretty fast. What do you do when you wear through your tile? How do you match the two surfaces after starting a new tool?

[PhnxCaller]

The turntable appears to have variable speeds, does this machine have a DC or AC motor? I'm looking into building a grinding machine like this one. Do you have any hints or details of the mechanical workings? I'm currently polishing a 12 inch mirror (F/5), and have a 18 inch blank just waiting to be ground, a machine like this definately would be handy!