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How to Do Lens Grinding

Lens grinding is a process many expert photographers and astronomers are familiar with, and one way to salvage a cracked lens when there is no suitable replacement. Practice on a blank lens a few times to get the hang of the grinding technique before moving on to creating a new lens for use in a telescope or camera.

Things You'll Need

Drop cloth
Glass of water
Blank lens
Measuring spoons
5-micron aluminum oxide grit
4-inch x 4-inch x 1/4-inch glass sheet
3-micron aluminum oxide grit

Instructions

- 1
  Place a drop cloth over your kitchen table. File the edges of the blank lens and the grinding lens with an emery board so that it will not cut into your hands.
- 2
  Place your blank 8-inch x 10-inch lens on the table. Make sure you can walk around the table and still reach the lens.
- 3
  Combine about 1/8 tsp. of 5-micron aluminum oxide grit with 1/8 tsp. of water, and spread it on your blank lens.
- 4
  Hold the grinding glass in your palm and press it against the blank lens. Work it in approximately 2-inch circles, adding water as the slurry dries out.
- 5
  Wash the lens off with water after about an hour of grinding.
- 6
  Mix 1/8 tsp. of 3-micron aluminum oxide grit with 1/8 tsp. of water, and grind it onto the lens with the same 2-inch circular pattern. Add water as necessary.
- 7
  Wash the lens with water once it has become uniformly white in color. Your lens is now ready to be polished.

Astronomy