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heavy at the bottom, and medium at the top, while No. 5, a horizontal hollow cyl. inder is shaded in an opposite manner, as will readily be seen. Additional effect is gained by using the heavy shade lines as described in the preceding article.
In drawing these shade lines, the efcect of shade is gained entirely by the closeness of the lines together, the heavy shading being produced by drawing the lines closely together and the light shading by giving considerable space between the additional effect ng given by breaking the lines as appears on most of the figures. The skill in doing this work comes from the ability to vary the spaces between the lines in such a manner that the figure will appear cylindrical at all points, and nowhere flat, as it would it the spacing was not varied continually.
The greater the diameter of the cylindrical figure, the greater should be the space between lines at the lightest point. The proper spacing of these lines is gained only from practice, it being a thing that cannot be reached from any exact instructions, or from measurement.
To those who are not interested in the inking of drawings, we would say that this shading can be done also with lead pencil. In Fig. 63, No. 1 shows an elbow shaded. The curved lines are all struck from the one center, and should be put in first, and the straight lines connected with them afterward. In shading branches, as Nos. 2 ard 3, the lines of intersection should be drawn in first, and
the shade lines of the branch should end at those lines.
Fig. 64 shows the principle of line shading applied to a system of piping.
As we have already intimated, this work is more ornamental than otherwise, and a knowledge of its use will often be found handy. As our regular practice exercise, we give this time, Fig. 65, an ele vation of the hot and cold water supply system for a two-flat house, and have shown the lines of pipe as single lines, the cold pipes being represented by solid lir and the hot by dotted lines. This method is often preferable to using two parallel lines to show the pipe, as it is simpler to draw, takes less time, and often shows off the work fully as clearly. It will be understood that our illustrations being designed for reproduction as cuts in a paper, have to be drawn in black ink. Under ordinary conditions, different colored inks could be used to advantage, however. For instance, instead of dotting the hot water pipes, as we have to in this case to make our distinction from the cold water, the hot water pipe might be put in with solid red lines, with good effect. If desirable, a back air system might be put in with one color, while a different color was used on the drainage part of the work.
Sometimes, also, it is required to make a drawing in which part of the work is old work, and the rest new work. In this case, one color to show the old and an. other to show the new, makes good work, and is more readily distinguished.
concerning sectional draw- boring pieces must be made by reversing
valuable aid in the clear rep- posite angles, just as No. 2 shows. It resentation of many kinds of work, it will be observed that in drawing the secwill be worth our while to devote some space to their consideration. From a comparison of Nos. 1 and 2 in Fig. 66, we shall be able to see wherein the value of sectional drawings lies. No. 1 represents a Fuller bibb, and
船! the dotted lines represent the inside working parts.
No. 2 represents the same thing, but instead of drawing a plain view as in No. 1, the bibb is considered to be cut through along the center line, and the front balf
Nol. set aside. This allows a full view of the other half. A sectional view of the bibb is a view of this half section such as No. 2 gives, and it will be seen at once that the sectional view is far clearer than that shown by No. 1. To show that it is a sectional drawing, the part that is cut through is always sectioned or crosshatched. By this is meant the parallel lines drawn close together, which desigAate the body of the bibb. These lines nay be drawn with either the 45 deg. or 30 deg. triangle. Every point of any given piece should be sectioned in the
No 2. same way. For instance, the inlet end of the bibb, which screws onto the body, is represented in the drawing by a section of metal above the center, and one below, both of which, being a part of the
FIG. 66. same piece, should be sectioned by lines drawn in the same direction and at the tion the working parts have been drawn same angle. It is often the case that plain, and not in section. The idea is al. these sections are represented by differ- ways to make any drawing show the obent colors instead of section lines, the dif- ject it is made to represent with the ferent colors representing different pieces greatest possible amount of clearness, and of the article in question.
it will be found in this case that the bibb When section lines are used, and the is shown much more clearly by leaving different sectioned parts are in contact the working parts plain, instead of sec.
line of soil pipe underground, A full black section looks well on such work, better in fact than the section lines, which are really used mostly on larger surfaces. To distinguish the lead joints from the pipe, they are made with small dots. The concrete floor may be made as we have indicated, and the ground surrounding the pipe in an indefinite manner, by having short lines made with the drawing pen, and interspersed with lines made with a common pen.
In Fig. 68 we have represented part of the base of a water closet, connected by brass flange of a certain style, with the lead bend; the fixture being vented from the bend. This we give to show the section of several different materials brought together on the same drawing.
It is a common thing with draughtsmen, to use certain different styles of section for different metais, especially in the drawings of machines, but for our use this is unnecessary, the main point being the use of such styles of sectioning as will clearly distinguish the different parts of the same drawing, one from the other. Thus in Fig. 68 the crockery is shown in section by dot and dash lines, the rubber gaskit by a fine dotted surface, the brass flange by 45 deg. section lines, the solder sections by 45 deg. lines drawn in the opposite directions, the lead by solid black surface, and the wood by lines representing the grain of wood. It will be noticed that the back air pipe is in sections only a short distance up, after
FIG. 67. tioning them in the manner that the rest of the bibb is seen.
No. 1 of Fig. 67 represents a sectional view of a certain type of water closet. In this case the whole section is of one piece only, and in such a case, a solid black section looks well. This could not be sectioned in this manner if there were several parts to be sectioned for in using a solid color, there would be no way of making a distinction between the several parts. In plumbing drawings it is often required to represent water, and we know of no better way than that shown in connection with the water closet, that is by horizontal light lines, made up of alternate dots and dashes. It will be observed that in a sectional view of the water closet, the flushing rim would be cut through at either end, but the main part of the rim, curving backward as it does, away from the line of sectioning, would be drawn in full, in the manner in which we show it. No. 2 represents a