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Drafting Room Equipment and Practice

drawings, shop, structure, detailed, usually and draftsman

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DRAFTING ROOM EQUIPMENT AND PRACTICE Introduction. Structural drafting may be defined as the art of making drawings of certain objects and placing thereon dimen sions and other notes 'which when taken together will convey the necessary information for the manufacture and in some cases the erection of the structure under consideration.

In the making of these drawings great accuracy in drafting is riot necessarily required. The chief requisites are that the letter ing and dimensions should be so clear that no misunderstanding is possiLle. Dimensions not given should never be scaled by the draftsman or workman, but the actual value should be ascertained by consulting some one familiar with the work.

Classification of Drawings. The classes of drawings which are made in a structural drafting room are: the stress sheet; the assem bly, or general detailed, drawings; and the shop drawings, or, as they are more often called, the detailed drawings.

The stress sheet is a tracing upon which is usually shown a skeleton outline of the structure upon the lines of which are marked the stresses which are caused by the traffic or other forces to which the structure is subjected, and also the size and shape of the mem ber designed to withstand these stresses.

The assembly or general detailed drawings usually give several views of the structure as it appears after it has Leen erected. en these views are shown to scale the members as they appear in the finished structure together with all the rivets and other details necessary for its completion. The overall dimensions are usually given and also any other dimensions which are necessary for the draftsman to complete the shop drawings. While the size of the members and their connections, as well as the number of rivets required, are always given, yet in a few cases the length of the member or shape and the individual spacing of the rivets are also given.

The shop drawings, or detailed drawings as they are more often called, consist of views of a certain member of the finished structure so dimensioned that it may be constructed by the men in the shop. It requires greater skill and more experience to make

the assembly drawings than it does the detailed drawings, but in each case the men must be familiar not only with the drafting prac tice but also with that of the mill and the shop.

Drafting=Room Personnel. A drafting-room force consists of an engineer, a chief draftsman, squad boss, checkers, draftsmen, and tracers.

The engineer has charge of the plant as well as of the drafting room and is directly responsible for the ordering of all material, the manufacturing of the structure and its shipping to the place of erection. He conducts the correspondence, keeps track of the work in the drafting room and in the shop, and, in case his plant is one of many of a large corporation, makes weekly or monthly reports to his superior officers. In case his plant is a small one, the en gineer usually does most of the work of designing and estimating.

The chief draftsman is directly responsible to the engineer for the getting out of the detailed plans or shop drawings and also ordering of the material.

The squad boss reports to the chief draftsman and his duty is to keep track of and to get out the drawings of any particular struc ture which is assigned to him by the chief draftsman. The squad bosses usually have from three to four to as many as twenty drafts men under them, according to the magnitude or the number of structures which they are responsible for.

In addition to the draftsmen are the checkers, certain men usually of great experience in matters relative to mill and shop as well as drafting-room practice. It is the duty of these checkers to go over the draftsmen's work, see that all errors are corrected, and then finally sign it as approved. The checker only is held re sponsible for mistakes which then may be left upon the sheet.

The tracers are for the most part young college graduates or apprentices, and their office is simply to trace the drawings which are handed to them by the draftsmen.

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