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Another Method of Drawing Lines Perpendicular to Each Other at Common Angles. closely can derive much benefit from the GH will be the line desired. knowledge of the subject gained.
This latter statement may often be put If two lines are to be perpendicular to to use, as we may see from Fig. 28. In each other at common angles, such as making drawings of plumbing work, it 30 deg., 45 deg. and 60 deg., the problem is far oftener the case that a branch is is simple, and may easily be seen by refer taken from a horizontal or vertical line ence to Fig. 27.
of pipe than from a line running at odd The line AB is drawn at 30 deg. with angles. A regular Y branch is always
The Main Pipe Drawn With a Tee Square-Lines of Branch With 45 Degree Triangle. the horizontal, and can be obtained sim at an angle of 45 deg. with the main line ply by drawing a line along the edge of of pipe. Therefore, in laying out work, the 30 deg. triangle placed against the tee such as shown in Fig. 28, the main pipe square. To obtain a line at right angles is drawn in with the tee square, and the to A B just reverse triangle No. 1 to the lines of the branch are drawn in with
the use of the 45 deg. triangle in posi. tion No. 1. Lines representing the hubs are put in with the same triangle in position No. 2.
In Fig. 29 we show right and wrong methods for drawing quarter and eighth bends, and in Fig. 30 like methods for running traps. We do this in order to show our readers some of the mistakes which it is natural for a beginner to make, and which he can the better avoid after comparing wrong constructions with correct. The common quarter bend is a compact fitting as No. 1 will show, and the mistake often mado is in giving it the long sweep shown in No. 2, although there are special fittings made after the manner of No. 2. The same fault is often found in the drawing of eighth and other bends. In drawing the quarter bend, first run the horizontal and vertical lines, then with the compasses set on a center close to the intersection of the two inside lines, describe the curves so that they will run smoothly into the respective lines. Of course both curves are struck from the same cen. ter. Many times the eighth bend will be used between a Y branch and a straight run of pipe. In this case, draw in the lines for the Y branch and the straight line, then connect these lines with the proper curve. Not until this is done should the hub on the branch or on the bend be drawn. Now with reference to
Right and Wrong—Quarter and Eighth Bends.
Showing How Curve of Trap is Made Too Low Down.
Model for Students to Work Out—Combinations of Pipe and Fittings as we give it. This should be drawn on some scale, at least no smaller.
the running trap of Fig. 30. The common fault in drawing this fitting is to make the curve of the trap too low down, that is, to give the trap. a much deeper seal than is it really has. Another fault shown in No. 2 as compared with No. 1, is the length of the straight lines connecting the vent hubs with the trap. As seen in No. 1, these hubs set close to the trap, and are close together. We have taken up the construction of these particular fittings in order that use may be made of the instructions given in working out the exercise in drawing which we give in Fig. 31. We would suggest that with this figure as a model the student work out the combination of pipe and fittings as we give it, and on the same scale, or at least no smaller
scale. We believe, by applying the instruction which we have already given, that the beginner will be able to work this exercise out without much difficulty: To start with, run the main line of pipe right through, regardless of fittings, giv ing it a slight pitch, as it would natur. ally have. Then put in the trap, and work back. In using the lead pencil do not bear down so heavily that when it comes to erasing lines later, to show in the fittings, the lines cannot be entirely erased. We should have stated previous to this that a hard lead pencil, preferably 6H, should be used, as it makes much cleaner work than a soft pencil. The very small curves, such as seen on the heads of hubs may best be put in by hand, rather than with instruments.
of plumbing systems is one of well for us now to consider the general
subject which we are studying, The only requirements for making these and even though we are hardly able as views are the plans of the several floors