ART
BEAUTY & WELLNESS
CRAFT
CULTURE & HISTORY
ENTERTAINMENT
ENVIRONMENT
FOOD & DRINKS
REVERSE ENGINEERING
SCIENCES
SPORTS
TECHNOLOGY
WEARABLES
Magnifying Glass from a Hand-Ground Lens
A magnifying glass is a convex lens in a frame with a handle. A typical one has a focal length of 25 cm, an optical power of 4 dioptres, and is sold as "2×": its magnifying power is 0.25 m × 4 + 1 = 2 for an eye whose near point is 25 cm. Here the lens is ground plano-convex from crown glass (refractive index about 1.52). For a plano-convex lens the focal length is R / (n − 1), so a 25 cm focal length needs a curve of radius about 13 cm. The lens is then set in a turned wooden ring with a handle; those sizes are ours.
Advanced
2–3 days
Instructions
1
1
Grind the lens
Grind the lens
Following the lens-grinding blueprint, grind one face of a glass disc to a spherical curve of about 13 cm radius, working down through the grits, then polish it clear with cerium oxide on a pitch lap. Leave the other face flat.
Materials for this step:
Glass Sheet1 piece
Silicon Carbide Grit200 g
Cerium Oxide Polish50 g
Pine Pitch Glue100 gTools needed:
Ruler2
2
Check the focus
Check the focus
Hold the lens in sunlight and move a card behind it until the spot is smallest; the distance from lens to card is the focal length and should be close to 25 cm. Do not look at the Sun through it.
Tools needed:
Ruler3
3
Turn the frame
Turn the frame
Turn a ring from a hardwood blank with a groove on the inside just wider than the lens edge, and part it off.
Materials for this step:
Maple Bowl Blank1 pieceTools needed:
Wood Lathe
Gouge
Parting Tool4
4
Turn the handle
Turn the handle
Turn a handle from a hardwood dowel and fix it into a hole drilled in the ring.
Materials for this step:
Hardwood Dowels1 piece
Two-Part Epoxy5 mlTools needed:
Wood Lathe5
5
Set the lens
Set the lens
Saw the ring through at the handle, spring the lens into the groove, glue the cut closed and wax the wood.
Materials for this step:
Beeswax10 gMaterials
8- 1 piecePlaceholder
- 200 gPlaceholder
- Placeholder
- 100 gPlaceholder
- 1 piecePlaceholder
- 1 piecePlaceholder
- 5 mlPlaceholder
- 10 gPlaceholder
This blueprint makes
Related Blueprints
These blueprints share knowledge with this one — techniques, materials, or principles that connect them in the learning graph.
CC0 Public Domain
This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.
Support the Maker by purchasing products through their Blueprint where they earn a Maker Commission set by Vendors, or create a new iteration of this Blueprint and include it as a connection in your own Blueprint to share revenue.