This section is from the "Modern Machine Shop Construction, Equipment, And Management" book, by Oscar E. Perrigo. Also see Amazon: Modern Machine Shop Construction, Equipment, And Management.
The department of design. The real work of the draftsman. Routine of the room. General rules. Keeping the time. Drawing materials. Tracings. Poor materials is poor economy. Brown or black prints. Sizes of drawings. Too many sizes not desirable. Drawing cards. Desirable scales for drawings. Dates on drawings. Draftsmen's names on drawings. Shade lines. Dotted lines. Center lines. Dimension lines. Dimension figures. Conventional section lining. Titles. Plain lettering desirable. Mounting blueprints. System of machine symbols. Designation of machine parts. Marking patterns. Part numbers on drawings Storing and filing drawings, tracings, and blueprints. Construction of drawers for holding drawings and tracings. Separating drawings and tracings into groups. Strawboard filing sheets. Indexing and filing drawings. Issuing and recovering drawings. Orders for blue or brown prints. Card system for filing, issuing, and recovering blueprints. Adhering to the regular system.
The drafting room is the department of design, where we expect ideas to originate for improving the product of the shop, as well as the methods of doing work. It should have the most accurate and efficient, and at the same time the simplest system and routine in its daily work. The draftsmen should be relieved as far as possible of clerical work. Their minds should not be burdened with a long list of symbols or complicated rules. They should be free to give their best attention to the real business for which they are employed, that of designing and drawing, and thus make the drafting room in fact, what it is often facetiously called by the machine shop men, "the brain room." Therefore the men at the drawing tables should not be concerned about the making of blueprints, their mounting, their issue to the shop, or their recovery and storage. This is properly the duty of apprentices under the direction of the chief.
The routine of the room should be carried on quietly. Orders should be given only by the chief. Employees from other departments should be excluded unless sent by their superiors upon inter-department business. Draftsmen should not work over eight hours a day and should not be expected to sit at the board more than two hours continuously. If designing, this period may be too long, without the relaxation of walking about for a quarter of an hour. More and better work will thus be done and with considerably less fatigue to the men.
The time of the men on all work should be carefully kept on time cards in connection with a time recording clock, in order that the cost may be known with the same accuracy as in the machine shop. For this purpose each man registers both day time cards, showing the amount due him on the pay roll, and job time cards giving the time spent on each job and aggregating the same time as recorded on the day time cards.
One of the things which ought to receive careful attention is the selection of proper materials, particularly drawing paper and tracing materials. White drawing paper for the ordinary sizes of regular sheets should be purchased in rolls 36 or 48 inches wide and of such quality as to stand hard usage under the erasing rubber; to have a surface hard enough not to gather dust readily and yet with sufficient grain to take the pencil and ink easily; to lie perfectly flat on the drawing board and to be capable of damp-stretching if necessary. That of medium thickness will generally give the best satisfaction.
Tracings should be made on tracing cloth 36 inches wide and with a dull back. "Imperial" tracing cloth, while rather more expensive than some other kinds, is the more economical in the end. It is poor policy to pay a draftsman for the extra time wasted by poor tracing cloth. The dull back cloth is convenient for applying œ pigment or soft lead pencil to the back in ordinary sectional views where a quick job is required.
Tracing paper should be used only for temporary jobs of a simple character. The same may be said of the use of bond paper, which has deceived so many draftsmen with the idea that the original drawings and tracing may just as well be made on one piece of material as a matter of economy. Such a tracing will become cracked and ruined in a short time, even with careful handling, while its tendency to wrinkle makes it a source of continual annoyance to the blue printer, who also finds that the pressure necessary for a good contact with the blueprint paper must be much more than with tracing cloth, or the prints will be blurred and indistinct.
The use of brown or black prints for such small diagrams, foundation plans, sketches, etc., as are sent to outside parties, is to be commended. These prints are very convenient and present a good appearance, particularly when the first print is used as a negative and preserved, while the prints from it, in brown lines on the white surface, are sent out. Where brown prints are used, any letters or figures to be filled in should be done in brown ink.
The most convenient size of drawings for use in the shop will depend to a considerable extent upon the product. While a large drawing may be very convenient, in that it displays the work on a large scale and is easily read by workmen, it is at the same time clumsy, often in the way, and more liable to accident than a smaller one. But if the drawings are too small they must often represent the work on so small a scale that the lines and dimensions will be crowded, and necessitate small letters and figures, whereby the liability to errors by the workmen is much increased.