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The Making of Structures 63

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THE MAKING OF STRUCTURES 63. Designing and Drafting. When bids have been asked for by parties, the firms desir ing to secure the work obtain a set of specifica tions from the parties desiring the work done, and also all data regarding the location, dimen sions, and layout. In some cases, the parties desiring the work done furnish a drawing show ing the general class of structure they desire, and, if the structure has many peculiarities, they may also furnish drawings giving the stresses in all of the members, and also the sizes of them. In case the drawing, with the stresses and sizes of members, is not furnished, the contractor makes one for himself, and then makes sketches from which he can very closely estimate all the material required. He then prepares his bid.

If his bid is accepted, he then sends this sheet, called the stress sheet, to the drafting room, where the detail drawings or shop draw ings are to be made. As soon as a contract is secured, a certain number is given it. This number is put on all drawings and correspond ence relating to it, and is painted on all material for the members of the structure. As soon as the stress sheet reaches the drafting room, one of the best men takes it, and from it orders all the material necessary to build it. This bill of material is sent at once to the rolling mills, and the stress sheet is turned over to the draftsman who makes the shop drawings.

The shop drawings show the size, dimension, and position of each piece that goes in the struc ture, and also the position of each rivet and rivet-hole. The draftsman also makes out a list of all the rivets required for the field and shop, and also a shipping bill which gives the length and size of each member of the structure.

After the draftsman finishes his work, it goes to the checker, who carefully goes over it and corrects the mistakes, if any. The tracings are then sent to the blue-print room, and several sets of prints are made from them. One set is sent to the purchaser for his approval; and after it is returned approved, sets are sent to the heads of the various shop departments which will have anything to do with the structure.

One set is kept on file in the office.

64. Making the Members. The templet shop begins work upon the order. Here holes are bored in pieces of boards so that when these boards are clamped to the piece of metal which is intended for part of a member, the holes will come where the holes should be in the member, and the ends where the end of the member should be. After the templet is made, it is marked with the order number and with the piece number, and has the notation signifying the kind of rivets and where the various cuts should be. It is then sent to the laying-out shop or division.

In many cases the steel for the structure arrives from the mills long before the drawings are made. It is unloaded, and placed in piles in the yard or in a shed near the laying-out shop. When the time comes that the templets are done and begin to come in, the material is brought in, one piece at a time as desired, and, if necessary, is straightened. The layers-out then take a piece, put it on their bench or trestle, clamp on the templet, and, with a center-punch and ham mer, make a small indentation in the steel in the center of each rivet-hole by placing the center punch in the hole bored in the templet and striking it a sharp blow with a hammer. The piece is also marked where it should be cut off, and also with notes regarding the rivets.

From here the piece goes to the shears, where it is cut to shape; and then to the puncher, where the holes are punched 1/lfi inch smaller than the diameter of the rivet which is to go in them.

From here they go to the assembling depart ment. Here the different pieces are cleaned of rust and scale, and painted one coat of some good paint on the surfaces which are to be riveted together. The different pieces which go to make up a member are then bolted together by bolts placed in the rivet-holes at frequent intervals. The member is now ready for the reamers.

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