Tuesday, March 1, 2016

Cutting Large Circles or Arcs? No Problem!

Dasco Pro 1405 Giant-Circle Beam Compass

Woodworkers have plenty of ways to mark out circles. Little circles -- up to perhaps 3” diameter -- are easy to cut with a hole saw. Anything bigger means that bringing out a different sort of tool like a jig saw or a band saw, depending on the use. Assuming you have a saw and the stock to cut, the problem becomes one of "How do I mark a curve that large???" You could root ask your kids for their compass (what the geometry teacher calls "dividers"), but they’re good for a radius of about six inches at most. What if you need to mark a curve with a twenty- or thirty-inch radius? Or larger? Do you struggle with string, a nail, and a pencil? 

Nope: you pull out your Dasco Pro 1405 Giant-Circle Beam Compass and a half-inch dowel, and quick as a whistle you've marked a curve. It actually is that easy.

  The Dasco Giant-Circle Beam Compass consists of two pieces of hard blue nylon. One half fits on the end of any ½” stock -- the beam -- to hold a shortie pencil (supplied, or you could "borrow" one from the neighborhood mini-golf) in place for marking. The other half slides along the beam and locks in place with a thumbscrew. Opposing the screw you’ll find a metal spike to serve as a pivot point. Instead of using a string, the two pieces mount on a dowel, metal rod, or piece of PVC pipe. The more rigid the material the better the resulting arc. The compass ships with a 12-inch rod for those medium-sized circles.

“Best practice" for setting the radius on a dowel is to mark the radius on scrap wood or the garage floor. I set my compass fairly close by hand; then I place the pencil point on one mark and hold it in place as I slide the "spike" to get the spacing correct (you might need a helper for longer radii). Fix the spike in place with the thumbscrew, and I’m good to go. With that rigid beam, there’s no need to worry about slop in the length like there might be with a string.

A beam compass like the Dasco Pro 1405 is a quick, inexpensive way to draw big curves like those you often run across on backyard projects. Not only that, but once you're drawn the circle you can use the "beam" in your project!


Plus: easily mark arcs and circles up to ten feet in radius
Minus: none
What They’re Saying: If your projects call for curves with a radius up to ten feet, don't despair: just get yourself a Dasco Pro Giant-Circle Beam Compass!

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