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.
Whether a pair of scissors be ground or filed, the marks or scratches left from the contact with the abrasive should all extend across the bevel in the direction of the line ED, Fig. 1, and never in the direction of the line GF. If the cutting edge be examined under a magnifying glass, the tool marks or scratches left by the sharpening process will be very plainly seen, and where these scratches intersect with the face HI, Fig. 2, of the blade, they will appear as teeth along the cutting edge IK.
Ill: The Direction of the Grinding Tool should be Slightly Sloping Toward the Handles
As a pair of scissors close, the natural tendency is to thrust the material to be cut out of the angle ABC, Fig. 1, but if these small teeth formed on the cutting edge point in the direction of the line ED, this slipping action is prevented or retarded because the fibrous material adheres to the fine teeth on the cutting edge of the blades.
Wet paper, silks, mohair cloths, etc., can be sheared with perfect ease And
Dispatch, when scissors are sharpened in this manner. The same principle holds good for metal snips.
The angle HIJ, Fig. 2, varies according to the material to be cut, and the type of shear. A greater angle is required on metal shears than on shears for domestic uses. - Contributed by A. Clifton, Chicago.