ABC of the steel square and its uses

Now run parallel lines off the tangent B for the shank; this completes the face mold, which is now ready for the face of the plank. Wreaths for stairs with flights which stand at either acute or obtuse angles to each other may be set out by the methods that have been here described. The only difference, practically, is that the bed block is made acute or obtuse to suit plan of tangents. The device shown at Fig. 85 has been found to answer excellently for striking out ellipses. To make this, procure two screws ¾ inches long, also a piece of brass tube that will just slip on the plain part of the screw without shaking. Counter sink out the ends until the screw heads are flush; cut two pieces off the tube three-sixteenths and file up true—these pieces are best held by sinking them with a bit in a piece of hardwood. Now when about to strike an ellipse, drive these screws in with the collars on to half major and minor, measured from the point of the trammel to the inside of the collar for the major, and to the outside of the collar for the minor. It will be found that if the collar has been made true, the trammel will slip around the curve without causing the square to slip about, the collars acting as rollers.

W. T. Jones, Boise City, Idaho, would like to know of a ready way to frame hip roofs and roofs of irregular or different pitches with the steel square, including lengths and bevels of all rafters.

Answer: These problems along with many others are discussed and explained at length in my larger works on the Steel Square, but the following, which is somewhat condensed, does to some extent cover Mr. Jones’ inquiries:

Suppose A, B, C, D, Fig. 86, to represent one end of a hip roof with a span of 24 feet and a 10-foot rise. The side rafter I D shown in top sketch will have a run of 12 feet. The common rafter at the end of building, I L, has a run of 16 feet, with the same rise, so that the ends and sides of the roofs have different pitches. The lengths and cuts of the common rafters are obtained as shown in Fig. 87, by taking 12 on the blade and 10 on the tongue of the square and measuring across, giving the length of the side rafter, from which one-half the thickness of the ridge, measured square back from the plumb cut, must be deducted. The blade gives the foot cut and the tongue the plumb cut. The length of the end rafter is obtained by taking 16 on the blade and 10 on the tongue, which will of course give the respective cuts also. The same results may be obtained by applying the square to a straight edge and marking along the blade and tongue, which will give a gauge line to which a bevel may be set. By taking 16 on the blade and 12 on the tongue, as shown in Fig. 90, the run of the hip rafters, 20, is obtained.

Referring to Fig. 88, it will be seen that 20 on the blade and 10 on the tongue give the seat and plumb cuts of the hip together with the length, after one-half the thickness of the ridge has been deducted from the side cut. The side cut is found in a slightly different way from that of a regular hip or valley on an ordinary roof. The common method is to take the length of the hip on the blade and run on the tongue, but this will not work in this case, as the run of the hip does not be at an angle of 45 degrees as in ordinary roofs. The line B J in Fig. 86 must first be obtained, as shown in Fig. 89. Joint one edge of a board and square up the line B L. Measure one-half the width of building—in inches—on this line, 12 in this case, and with the heel of the square at the point B, move the square until 20 on the blade touches the edge of the board at E. The tongue will then give the point J 15 inches; which is the length of the line required.

Then take this line on the tongue and the length of the hip on the blade, Fig. 90, and the blade will give the bevel of the hip to lie against the ridge. As a general rule, hip rafters are not backed, but if such is desired the lines for backing can be found by setting it to the foot cut of the hip rafter. Make O R square with S O and gauge back as shown in the diagram A. Do the same on the other side, using the distance T R instead of P S. The point O is of course at the center of the line T P.

For lengths and bevels of jacks, proceed as follows: For end of roof, and set 2 feet on centers, take a board and apply the square to it, as shown in Fig. 91, with the length of the end rafter on the blade and the run of the side rafter on the tongue. Space off 2, 4, 6, 8 and 10 in. on the tongue after marking along both blade and tongue. The lines, AA, BB, CC, DD, EE, will give the length of the jacks, as well as the side cut to fit the side of the hip, the square being moved down along tongue line, while the run of the end rafter on blade and its rise on tongue will give the seat and plumb cuts. For the side jacks, Fig. 92 gives the same method, only that the length of the side rafter is taken on the blade and the run of the end rafter on the tongue. If it is so desired, the length of the jack rafter A¹ A¹ may be deducted from the length of the common rafter, which will give the difference in the lengths of the jacks.

The rules and diagrams, given herewith will apply to valley as well as hip rafters, and may be relied upon as being accurate if closely followed.

RULE—See Fig. 87.

RULE—See Fig. 91.

Blade gives Side Cut of Jacks.

RULE—See Fig. 92.

Blade gives Cut of Jacks, also Sheathing.

These matters have been discussed at length, in trade journals and also in my larger volumes on The Practical Uses of the Steel Square, but the foregoing treatment of the subject is on somewhat different lines and will prove interesting.

John Wilberforce, Toronto, Ont., wants to know if a wreath piece for a single-pitch rail with level landing can be set out with the Steel Square.

Answer: Yes, the problem can be solved as follows:

Set out on a board the plan of the wreath A (Fig. 94). Draw the outside circle and the inside and center line of same, showing also the joints. Set out the pitch off the shank; square up the center outside and inside lines from the plan on to the pitch. The thickness of the wreath piece is found by drawing a section of rail under the pitch line B. Set out again the half-width of the well; square off the pitch lines to the half width; this gives major and minor axes of the ellipse, as shown in the development (Fig. 94). Lay the square on the axis. Get a light piece of lath, drive in a nail at the half major, and one at the half minor; describe the inner ellipse line on the piece of timber from which the wreath is to be formed; pull out the nails, and repeat the process for the center and outside lines. Draw the shank and also the point as shown on the board.

Now cut at the joints, allowing an ⅛-inch for the fitting of the joint after the wreath is cut and roughed out. Use another piece of timber about 2 inches thick, to form the bed block, and cut it to the pitch accurate and square in thickness. Screw or pin it to the under side of the wreath piece (see Fig. 95), taking care to get it parallel with the shank, and the nails in clear of the saw. Then proceed to cut the wreath with the band saw, beginning at the circular part, and work it to the shank inside and outside. This operation should be performed most carefully with a narrow band saw, having a strong set and strained tight, feeding very slowly. The wreath should require hardly any spoke shaving. Knock off the block and draw a chalk mark across the table, just in front of the teeth. The use of this line is to assist the operator to get the outside of the wreath always touching this spot in front of the saw. He must carefully lower his hand until it is down level at the shank end. The top is cut first, and the saw should skim along the outside top arris, giving a sweep that cannot be excelled in graduation of curve. Then set a gauge to the thickness of the rail, mark a line on the inside of the wreath, and cut as before. With a little practice a wreath can be turned off the band saw ready for molding. When the shank is too long, it is always better to nail the bed block on top of the wreath, and cut it upside down, thus getting the curve portion near the table. Then the shank can be run in with the band saw when the block is knocked off. The foregoing is for a single-pitch wreath as used for stairs with level landings and narrow wells. Where the rails are pitched both ways, the bed block has to be cut at the double inclination. (See preceding answers.)

INDEX

A. B. C.
STEEL SQUARE—THE STEEL SQUARE AND ITS USES.

Division A.

Preface1

Introductory remarks3

Some useful advice7

Framing posts, girts and braces9

Testing a steel square11

Practical uses of the steel square13

Some rules for roof framing16

Octagon rules19

Lines on steel square explained22

Varieties of squares29

Bridge-builder’s square31

Crenelated square34

Test diagrams37

Degrees on the square44

Division B.

Introductory47

Slotted fence48

Laying out stairs49

Laying out rafters51

Metal fences53

Fence adjusted for stair strings55

Brace rules and diagrams57

Regular and irregular runs60

Roof framing63

Cutting rafters64

Octagon rafter bevels65

Hip and valley rafters65

Jack rafters66

Bevels for hips, valleys and jack rafters66

Measuring rafters68

Different pitches for roofs70

Some pointers in roof framing72

Roof diagrams79

Rise and run of rafters, hips and jacks82

Cuts and bevels for rafters86

Unequal pitches91

Hip-roof with deck96

Division C.

Introductory97

Diagram of hip-roof98

To cut jack rafters100

Hopper miters101

Questions and answers for correspondents102

Joints for obtuse or acute angles102

Drawing circle with square104

Laying out stair wreath with square105

Bevel for miter cap105

Face mould by the square106

Making pitch-board by the square107

To lay out braces, girts and trusses108

Braces, regular and irregular109

Diagram of braces in position112

Finding center of circles113

Stair with three windows114

Pitches and bevels for hand-rail115

Traces for hand-rail bevels116

Cutting out rails with band saw118

Diagram of hand-railing119

Tangents in hand-railing121

Getting horizontal trace of hand-railing122

Instrument for laying out hand-rails124

Framing a hip-roof125

Diagram of hip and rafter lines126

Rafter measurement on the square127

Bevels and cuts of roof128

Plumb and horizontal cuts for hips129

Length of rafters, hips and jacks on square131

Rules for cutting rafters133

Stair wreath for level landing133

Wreath for single pitch rail134

Block for cutting wreath135

Square and plumb136

Transcriber’s Notes

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