This puzzle is described in the book “Dissections: Plane and Fancy” by Greg N.Frederickson. According to the book this 7 pieces dissection is discovered by Lindgren in 1964. The aim of this puzzle making a greek cross (plus shape) by using this seven pieces.
This dissection is produced by different producers as puzzle. On the photo you can see my own simple craft example. But there are really beautiful examples of this puzzle. You can see one of them from Rob’s puzzle page.
For me this is an interesting dissection. Because this dissection include arc segments. I saw this puzzle on different books and articles. There are some patterns for scaling and drawing this puzzle but I can’t find a good description about how to draw it geometrically. I was curious especially about arc radius. For this reason I decided to draw it with a 2D engineering CAD software.
At the beginning I wasn’t planing to make a physical copy. I wanted to find how to draw geometrical dissections. This is similar to solving geometry problems and very funny. But I found some interesting points and for sharing here I prefer use my own photo and I made a copy. I made this puzzle from wood with a scroll saw. I describe this tool as “Poor man laser”. With a little experience and patience you can make a lot of laser cut puzzle with this machine.
This puzzle looks like a crescent moon. But in reality it’s not a real crescent Because a real crescent shape is the intersection of two circle. But in this dissection the ends of crescent are line segments. And the ends of crescent is very thin and long. I think theoretically this is a perfect dissection, but for making a physical copy it’s not a good dissection.
The most interesting part for me is “how to draw”. But this is a long explication for sharing here. For this reason a prepared a small free PDF document. (113 KB) This document is a step by step drawing tutorial for this puzzle and include a pattern page if you like make your own without drawing this. You can download from here. This is my simple method for drawing dissection puzzles. I start with known things and search unknown points like solving an equation. I draw a lot of dissection puzzle with this method. I think using a 2D cad software for drawing that kind of dissections make everything easier. “Draftsight” is a good free 2D drawing software. Very similar to “Autocad” but free.
I hope this document may be helpful to you for drawing other dissections too.
DIY Puzzles 