Use a Coin for a Radius

Instead of using a compass, try using a coin when marking a radius for a corner.

This topic came up during a video shoot for a woodworking project. Someone asked what coin would equal a 3/4″ radius. I honestly didn’t have an answer, but that I often use a two shillings coin (1956 to be exact) that I keep in my pocket all the time for making quick radius marks.

Well, it turns out that coin is about 1 1/8″ in diameter, which would give me a rough 9/16″ radius.

So I decided to check out other coins. Now, I know other woodworkers have done this before, but I figured I’d check it out myself and list the dimensions here:

Eisenhower dollar = 1 1/2″ diameter = 3/4″ radius

Kennedy half dollar = 1 3/16″ diameter = 19/32″ radius (roughly 9/16″)

Sacagewea dollar = 1 1/16″ diameter = 17/32″ radius (roughly 1/2″)

Quarter = 7/8″ diameter = 7/16″ radius

Nickel = 13/16″ diameter = 13/32″ radius

Penny = 3/4″ diameter = 3/8″ radius

Dime: 11/16″ diameter = 11/32″ radius (roughly 5/16″)

Published in: on February 23, 2010 at 1:40 am  Leave a Comment  

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