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.
The frame is constructed of cold-rolled steel, 1/4in. in diameter and 17 1/2 in. long, bent into the shape shown and then cut in two parts at A. Starting at a point about 5/16in. from the ends made by the cut, drill 1/8 - in. holes, then space three other holes 1 in. between centers and drill them 1/8 in. in diameter.
A piece of steel tubing, 1/4 in.in inside diameter and 6 3/4 in. long, is notched on the ends to receive the pins B and C. Slots are cut in the ends D and E. to admit the blade of a saw, and half-round notches filed on the outside surface for holding pins used in the hole of the saw blade. The spring of the steel will be sufficient to keep the saw blade in place. The 1/8-in. holes in the frame will permit adjustment for different lengths of blades. - Contributed by Clarence B. Hanson, Fitch-burg, Mass.
Ill: The Frame is Shaped of Cold-Rolled Steel and Made Adjustable with a Piece of Steel Tubing