Posted by
Easy WoodCraft on
Nov 14, 2016
A circular plane (or compass plane, as it's often called) is another one of those specialized planes that'll you'll be glad you have when a project calls for planing a fair curve (
left photo). The most distinctive feature of a circular plane is that it has a thin, flexible sole (
right drawing). Adjusting the curvature nut forces the sole into either a convex or concave shape. The blade and cap iron rest on a frog that works much like that of any other metalbodied plane.
Although Record still produces the No. 020C shown here, you can occasionally find a Stanley No. 13 (highly prized by tool collectors) at a tool auction or on the Internet. I realize that many woodworkers would simply grab a belt sander or other electric sanding device to smooth a gradual curve; but a circular plane will leave a cleaner, more fair curve than you can achieve with one of those noisy dusty tools.
Convex planing
One of the classic uses for a circular plane is truing up the perimeter of a round work-piece, such as a table top. The beauty of using one of these planes is that when the circle is true, you'll know it: The plane's cutting action will slow significantly. To use a circular plane for this, start by adjusting the sole to closely approximate the curve of the work-piece. Adjust the plane blade for a fine cut and start planing. As with any plane, you'll need to be careful to plane with the grain, and not against it. This takes a bit more thought, since the grain direction will change periodically as you work around the top's circumference.
Concave planing
A circular plane also makes quick work of truing up an inside curve (
left photo). Though you can start as you did with a convex cut by adjusting the planes sole to match the inside curve, I've found that if you adjust it so that it's a hair tighter than the inside curve, you'll have better luck. A tighter curve on the sole allows the plane to fit tighter to the curve and makes it easier to lop off the high spots.
Once the high spots are gone, you can readjust the plane's sole to better match the inside curve. As with a convex cut, it's important to take extra care to prevent planing against the grain (
right drawing). This is one plane that will gladly bury its blade in end grain and tear out a big chunk of wood.
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