This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Fig. 34. Guide Sheet for Obtaining Correct Slant in Letters.
The only manner in which a person can become proficient in lettering is through practice. A piece of paper ruled up and having the slant of the letter placed upon it as shown in Fig. 34 will be found an excellent thing on which to practice lettering. Letters can not be made nicely and quickly as one would suppose. Care and time are required until the draftsman becomes proficient in this respect.
L. or Ls.
Angle or angles
[. or [s.
Channel or channels
I. or Is.
Z. or Zs
Zee bar or bars
T. or Ts.
Tee beam or beams
PI. Plt, or Pls., Plts.
FI. or Fig.
Pound or pounds
c. to c. or 4's
Center to center
Laft. or Latts.
Latticed or lattices
Lat. or Lats.
Lateral or laterals
Abbreviations. In the making of drawings certain abbreviations are used in order to save time and for the sake of convenience in many other respects. These abbreviations together with what they signify are given in Table IV. They should be carefully studied and should be written close to the material to which they apply and should at least be one-sixth to one-eighth of an inch from the material. Never write dimensions or letters so close to a line that they will interfere with the line. In writing dimensions at a considerable distance from the piece of material or place to which they apply, an arrow is used to indicate their proper position. In all such cases the arrow head should be at the end of the line which points to the place to which the abbreviation or dimension applies.
Fig. 35 illustrates some cases and also shows the form which the arrow should take in order to present a good appearance on the drawing.
Dimension and Material No= tation. Proper Placing. A drawing may be said to have been correctly dimensioned when any desired necessary dimensions may be obtained from it without it being required that any dimensions should be added or subtracted or divided in order to obtain the desired result, and when no unnecessary dimensions are upon the drawing. By necessary dimensions are meant those dimensions which are required in order that the material may be fabricated so that the finished structure is as desired. Dimension lines should be full, not dotted or dashed; guide lines, which are lines indicating the limits of the dimensions, should not extend beyond the dimension line. The dimensions should be placed where possible above the line and should not, as mentioned before, touch the line at any place. Dimension lines should be far enough from the piece which they dimension in order that the letters and figures indicating the character of the material and its size may be placed between the dimension line and the material itself. Fig. 36a shows good practice and Fig. 36b poor practice.
Fig. 35. Correct Use of Arrow and Line in Dimensioning.
Arrow heads are a source of trouble and should be made with care if the drawing is to present a good appearance when finished. They should be made as indicated in Fig. 36a and Fig. 36c, and not as in Figs. 36b and 36d. They should not consist as indicated in the figure showing the wrong construction, of a cross or halt cross of a straight or nearly straight line, but should have a gradual slope as in Fig. 37 where it is greatly exaggerated.
Fig. 37. Correct Arrow Head.
Fig. 3S. Correct and Incorrect Placing of Dimensions.
Dimensions as mentioned above should be placed above the dimension line where possible and the material should be noted so as not to interfere with the dimensioning. Figs. 3Sa and 38b show good practice and Figs. 38c and 38d poor practice. Sometimes it is necessary to place the dimensions as in Fig. 38c and 3Sd but never place the material notation as shown in the same figures. Fig. 38b gives the preferable method.
When several spaces are equal, the matter may be written as so many spaces at so much is equal to so much, or each space may be dimensioned separately as shown in Figs. 38a and 38b. In case the space is too small to write a single dimension in it clearly, the dimension may be put at one side and an arrow used to show where it belongs, Fig. 35.
In writing dimensions the inches should be given as well as the feet, and in case the inches amount to nothing or to a fraction, a cipher should take the place of the inches.
It is not necessary when all rivets are shop rivets to draw in each in such cases to put in the end rivets and to inidicate the spacing and every rivet when the spacing is the same. It is only necessary of those which lie between but which are not shown. Fig. 38b illustrates this. In case of field rivets all rivets must be shown. No departure from this rule should be allowed. Fig. 39 is an example of this. It is noted in this figure that although the spacing of many of the rivets is the same, yet all are shown in their proper place.
In placing dimensions where two or more members are detailed together, dimensions for the main member should run straight through from one end to the other. The dimensions of the larger member in so far as they are the same as the dimensions for the smaller may be used for the smaller member and additional or subdimensions be placed in convenient places in order to complete the detailing of the smaller member. As an example of this see Fig. 38a where the edge distances and the method of detailing should be noted, and Fig. 39 also where the edge distances are the subdimensions. In Fig. 39 two dimensions are given at one of the ends. This illustrates two methods of placing the same dimension. The dimension directly under the line of dimensions for the main member is placed in the preferable way. In the placing of subdimensions great care should be taken not to make them too small or to place them so that they interfere with the guide lines of the main dimension.