Draw big circles with this shop-made beam compass
It’s surprising how often I seem to have the need to make a circle for a woodworking project and my regular drafting compass is too small. Usually, I will search around the shop and kitchen to find a bowl or a bucket that is close enough to the size I need. If I need a really big circle, I tie a string to a pencil and create an arc. This poses accuracy problems, and sometimes the string stretches.
A few weeks ago Jay Kopanski sent me a cool compass he made out of oak. I knew right away I had to make one!
You can make this compass any size you want. Mine is 22″ long, which will create nearly four-foot diameter circles. The beam runs in a track made by cutting a sliding dovetail. You can do this with a router bit, but I found that using a table saw was easier and gives you more size and angle options. If you start with a board about 4″ wide, you will have plenty of material to work with and won’t have to cut thin strips without support. Cut the sliding beam first, then cut the channel it rides in to get a good fit.
