Thread: 200 year old hollow and round hand planes

Yet another great video Dave. Thanks again.

John

Planemakers used a variety of numbering schemes, the most common of which is to assign the plane a number based on the radius of the arc it cuts in 16ths. Using this scale a No. 12 plane would cut an arc with a 3/4in. radius. Most hollows and rounds cut a 60 degree arc of a circle.

Some good background on hollows and rounds here:
How to Buy Hollows & Rounds Molding Planes | Wood and Shop
Sizing Hollows and Rounds

The angle that the blade rests at would change the radius of the circle that the blade actually represents. Not much difference with smaller radii but once you get into larger sizes it becomes apparent. I made a few planes up for finishing masts and oars and it was definitely there in those sort of sizes.

Have fun,
Alli