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.
A bench stop for planing thin boards with a hand plane may be made in the following manner: Procure a piece of strap iron about 1/4 in. thick, 1 1/2 or 2 in. wide, and about 6 in. long. File or grind one edge sharp on top and drill a 1/4- in. hole through the center. Cut a slot in a board or in the workbench large enough to receive the stop A flat. Place enough strips of rubber or fit two coil springs, B, to raise the sharp edge out of the slot. Insert a screw in the hole of the stop and adjust it to the desired height by turning the screw up or down.