Monday, April 25, 2011

Make your own: moon calendar

I saw this moon calendar at some friend's a few months back. They use it for gardening (and judging by their crop this summer, it must work somehow!), but it can also be used for anything from fishing to getting a hair cut. Anyway, this particular one doesn't have as much detail as you would get from a moon calendar, but it is great because it's perpetual.

I took a photo of it so I could reproduce it at home.
I found a circular wheel with two dials that was originally meant to help people work out their mortgage repayments, which means I didn't have to start from scratch (thank you National Bank!).

I (re)used a piece of craft paper, and traced around the outside of the wheel. Then comes the hard part. The outside wheel has 28 increments with the 1 to 28 days in a month (days 29, 30 and 31 are shared with days 1, 2 and 3). So I worked out the spacing that I needed between each day with this formula: c=2πR, where c= circumference and 2R= diameter. When you divide c by 28, you get the width for each day.

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I traced the lines, making sure the length was the same for each one and corresponded to the distance between the big and small circles. Then I cut around it and glued both circles on my mortgage repayment calculator. Finally I wrote on the smaller circle.

It looks great on our black board!

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