This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
When a plane iron has been sharpened a number of times, it often becomes so out of square that the edge cannot be made parallel with the bottom of the plane block, even by using the lateral adjustment. Where this happens, the plane iron must be re-ground. If an emery wheel mounted in a polishing head or lathe is at hand, this can be easily accomplished. Loosen the plane-iron cap and screw it down at right angles to the plane iron, also reverse the tool rest as shown in the sketch. In this way the work can be done better and more
The Plane-Iron Cap Turned at Right Angles, Provides
a Guide to Grind the Edge
Straight quickly than by the usual method. - Contributed by L. S. Uphoff, Schenectady, N. Y.