In accordance with the method above stated, layouts are made, then material ordered for all details, and these layouts and copies of material bills are laid aside to be placed in the hands of the drafts man who detailed the subject. Before the material is ordered from the mills, these bills should of course be checked by another checker or by the squad boss.
In making layouts where angles are placed so that one of their legs is vertical, care should be taken to see that the horizontal leg is at the top in all cases where the angle is exposed to the action of rain and snow. If it is not in this position the angle, in case it is on a slant, will serve as a little trough clown which the rain and melted snow will run into the joint at the lower end. In case the angle is not on a slant it forms a pocket-like arrangement so that the snow and ice may lodge upon it to a greater extent than if it had the vertical leg downward. Rust will result and the angle will, there fore, deteriorate. In cases such as lower chords and diagonals of roof trusses, the vertical leg of the angle should extend upward, since here the angles are not exposed to the elements and it is some what of an advantage that the angle should catch any dust which falls upon it, and should hold it in order to keep it from dropping to the floor beneath.
Allowances for Planing and Cutting. Single Lengths. When material is ordered it should be so ordered that it will be sure to be of the correct length when it gets to the shop. If the material is ordered in single lengths, that is, the length ordered to go into the finished structure without being cut in two or more pieces after it gets to the shop, it is customary to make some allowance for planing off the ends or for chance errors in the mills where the men may not be careful enough in elating and may accidentally make the cut a short distance on one side or the other of the mark which would give the exact length The customary allowances for single lengths are given in Table I.
Multiple Lengths. In cases where there are several pieces of the same size and length, they may, for convenience in handling, be ordered in one piece at the mills and cut into lengths after they reach the shop. In this case, however, care must be taken that the
multiple length is not too long to ship on an ordinary freight car. The allowances to be made in such cases and the general rules are given in Table II.
Allowances for Pin Material. In case material is ordered for pins, it is necessary that certain allowances be made for turning and for ordering in multiple. The following very general rules are given in Table III.
Allowances for Bending. In all cases where angles have to be bent, additional material is required. In such cases the following rules are applicable: (1) In the ease of Fig. 7a. Figure length on e.g. line of angles and add 1" for each bend when the angle of bend is not more than about 30'; add 2" for each bend when the angle is between 30° and 60°; over ask for special instructions from the forge shop.
(2) In the case of Figs. 7b and 7c. In the case of sharply curved end angles or when sharp bends are made near ends, add to the length figured on the e.g. line as follows: 3-inch angles add 4"; 4-inch angles add 5"; 5-inch angles add 6"; 6-inch angles add 7"; 7-inch angles add S"; and S-inch angles add 9".
Shop Bills. In order to facilitate the getting out of certain articles which are of the same general form but of different dimen sions, and for convenience in tabulating information relative to certain material either before or after it has been assembled into members for structures, certain bills called "shop" bills are used. These bills, which save much drafting and much letter writing, may be of almost any character to suit the practice of the plant. Figs. S to 26 give the headings of various bills and Fig. 27 gives the head ing of a bill which is used in case it becomes desirable to change an order which has been sent in. The lower part of Fig. 27 is suitable for all of the other bills.
These bills are made on thin paper so that prints may be made from them and sent to the various shops concerned. A copy of each should also be filed in the engineer's office, and all bills of each job should be kept together by binding in some way.