Side Rails

Fig. 2. Legs

2. If drawings are furnished, detail each of the parts to be made, i. e., draw them out full size, or to a large scale, and note all the dimensions necessary to make them. (See Fig. 2.)

Fig. 3.

We do this to make sure that we really understand the drawing furnished us, for it is quite possible to make a beautiful copy from a drawing without understanding it at all. If, however, we make detailed drawings of the parts from the assembly used, we must, of necessity, read the drawing.

3. From the assembly used make out a bill of materials (Fig. 3).

We should never neglect this matter of making out a bill of materials for it again compels us to read our drawing.

Pointers:

1. A working drawing should give all the dimensions needed to construct the article.

2. Keep your pencils sharp.

Uncover about 1/4 " of the lead with the knife, but sharpen the lead on a piece of sand paper or a file.

Fig. 4.

3. The T-square is used as a guide in drawing horizontal lines.

Note: In all this work, the head of the T-square should be held firmly against the left hand end of the drawing board. If you are left handed, you will, of course, use the right hand end of the board.

The triangles are used in combination with the T-square to draw:

(a) Vertical lines.

(b) Angles of 45, 60, 30, 15, and 75 degrees with the horizontal.

Fig. 5.

5. Lay out a plate by means of long, light, indefinite lines. (See Figs. 4, 5, 6, 7 and 1.) As shown by these figures, the steps to be taken are as follows:

(1) Locate and draw lightly and of indefinite length the main horizontal lines. (See Fig. 4.)

(2) Locate and draw the main vertical lines. These lines should also be light and of indefinite length. (See Fig. 5.)

Fig. 6.

Name. Foot Stool

Grade. Scale

Bench No Date

Fig. 7.

(3) Block in all the diagonal lines, arcs of circles and other details. (See Fig. 6.)

(4) Go over the outlines of the figure with a heavy line. Circles and arcs of circles should be drawn over first. (See Fig. 7.)

(5) Dimension and letter the plate. (See Fig. 1.) Note the title strip used. The spacing of the guide lines for the lettering is shown in Fig. 4. Fig. 8 shows a Perspective or picture view of the finished stool.

6. Study the conventions used in dimensioning drawings as shown in Fig. 9. Study also Fig. 1 and Fig. 2, and note:

(1) That the arrow points are placed at the limits of the space being dimensioned.

Fig. 8.

Fig. 9.

(2) That in dimensioning a series of spaces the dimensions are, if possible, placed in one line and summed up just outside that line. (Fig. 2.)

(3) That the dimensions should not be crowded

(4) That a dimension is never placed upon a center line or a line of the object.

(5) That dimensions are kept off the figure as much as possible.

7. A scale drawing is one in which all the parts are drawn proportionately larger or smaller than the object.

8. The scale of a drawing should always be stated.

9. The dimensions placed upon a drawing always indicate the finished size of the object no matter what scale is used.

Fig. 10.

10. Letters and figures must be carefully made, if the plate is to look well.

(1) Equal height, equal slant and even spacing are the first essentials in good lettering.

(2) Standard capitals are 3/16" high. The first alphabet (Fig. 10) illustrates a simple Gothic vertical alphabet. After this has been mastered the second example of the same alphabet, with serifs added, may be used.

(3) Standard figures are 1/8" high with fractions double height.

11. The usual method of placing views is shown in Fig. 1.

The plan view is placed above and is what one would see if he were above the above object and looked down.

The end view shows the object as it would appear if one were looking at it from the position that it occupies on the plate.

Two views will often show all that one needs to know about an object in order to construct it.

12. Note the conventional lines shown in Fig. 11.

Fig. 11.

Pencil line - for lay-out.

Visible outline.

Invisible outline.

Dimension line.

Center line.

Projection or witness line.

13. The title of the drawing should tell:

(1) The name of the article.

(2) The scale of the drawing.

(3) Who made the drawing.

(4) The date it was made.

(5) Any other items, e. g., the number of the student's bench, the name of the school, etc., that may be of service to the user of the drawing.

Do not be afraid of putting too much into the title of a drawing, or of putting too many notes on a plate. Why?

14. A good working drawing is one that tells everything necessary to construct the article.

All letters and figures must be legible.

All lines clear, sharp, and not confusing.

15. Look up the following topics:

(1) "Sections." Find out when and why section views are used. What are "revolved" sections? Define "cross-hatching."

(2) Use of architect's scale.

(3) Making of tracings.

(4) Making of blueprints.

Fig. 12.

(5) Find out how to construct a regular hexagon.

(a) When one side is given;

(b) When the distance across the points is given;

(c) When the distance across the flats is given; Learn the draftsman's method (see Fig. 12); the method of "Euclidian" geometry; the method of the carpenter who uses his steel square. Ask some good mechanic to help you.

(6) Find how to construct a regular octagon when the problem presents itself in each of the ways mentioned in the case of the hexagon.

Note the solution given in Fig. 12. How many other solutions can you find?

(7) Draw a triangle (Fig. 13) with sides in the ratio of 3, 4, and 5 and note that one of the angles is a right angle. Why?

Ask the mason or the carpenter when and where he uses this theorem.

Fig. 13.

Fig. 14.

(8) To construct a triangle with angles of 30°, 60° and 90°.

(a) Draw a semicircle.

(b) With center at B, and a radius equal to the radius of the circle, describe an arc cutting the semicircle at C.

(c) Draw the lines AC, CB, and AB.

The resulting triangle has angles of 30°, 60°, and 90° as shown in Fig. 14. Why?

(9) Find how to bisect a line; an angle.

Ask some good mechanic what other geometrical problems he finds most useful.