ABC of the Steel Square and Its Uses

by Fred. T. Hodgson

These squares are furnished by the manufacturers either in polished steel, nickel plate or oxidized copper. The latter style is quite popular with some workmen, because of its not getting so hot when exposed to the rays of the sun.

Fig. 4.

The two sides of the square, shown at [Fig. 3], represent the carpenters’ popular square, No. 100. This square has been a special favorite with workmen for nearly thirty years, and is still looked upon by many as being the ne plus ultra of steel squares. I show both sides of the square in order to enable the workman to see, before he buys, the kind of tool he will get. Like the Nicholls square, this may be obtained in polished steel, nickel plated, or oxidized copper as the purchaser may desire.

Fig. 5.

I show the complete square, reduced to page size. Sometimes this square is catalogued by dealers as No. 1000, practically, however, it is the same square as the No. 100. If we examine this square we will find on the tongue near its junction with the blade a series of lines and cross lines (see [Fig. 4]), making a figure known as the “diagonal scale.” This scale is drawn to a larger size at [Fig. 5] and is shown alone and is used for taking off the hundredths of an inch. The line ab is here an inch long, and is divided into ten equal parts; the line cd being also divided into ten equal parts, and diagonal lines are then drawn connecting the points as shown in the diagram. Suppose we wish to take off 76-100 of an inch, we proceed as follows: Count off seven spaces from c, e, g, which equals 70-100 of an inch; then count up the diagonal line until the sixth horizontal line, e, is reached, when e f will equal the required distance of 76-100 of an inch, which is a trifle over ¾ of an inch.

Fig. 6.

Quoting from the table of directions given in Sargent’s circular describing this square, we have, for rafter cuts, the following explanation: “This run of a rafter set up in place is the horizontal measure from the extreme end of the foot to a plumb-line from the ridge end—from A to B, [Fig. 6].