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.
In inspecting cast iron, tests must be made to determine whether or not it comes up to the requirements of the specifications as regards quality. Inspection must also be made to see if the material is free from flaws such as blow holes, pockets of sand and unequal distribution of metal. Where the thickness cannot be measured readily as in the case of columns, small holes are bored to determine this. Where columns are cast in a horizontal position, as they generally are, the tendency is for the core to sag in the center, and therefore it is better to make this test near the center. A sharp blow of a hammer will often indicate unequal distribution of metal. A clear metallic ring indicates a thin shell and a dull heavy sound a thickness of the shell. If the edges are struck with a hammer and pieces fly off under the blow this indicates a brittle texture; a good quality iron should show only a slight indentation. Cast iron should be inspected also for straightness, accurateness of facing of bearing surfaces, and agreement with details. It is better to inspect cast iron before it is painted in order to the more easily discover flaws.
Relation of Engineer to Architect. An essential feature to be observed in all successful designing and detailing by the engineer, is co-operation with the work of the architect. This may seem to the student, at the outset, as a very simple point and one which will need little special attention. Yet the power to fully and quickly grasp the breadth of the architect's design, and its smallest details as well, and to make the structural design to fully harmonize with his work, will come only by persistent effort.
In some buildings, the work of the engineer, because of the character and purpose of the building, would determine conditions and features to which the architect must conform, but in general the reverse is true. For this reason the burden of harmonizing his work is generally put upon the engineer.
He must see what has been established by the architect and how much he must vary the natural course of his design to conform to these conditions. He must often study long, over what at first seems scarcely possible to accomplish without clashing with the architect's scheme. In the working out of such details and problems, he will need all his originality.
Interpretation of Drawings and Specifications. In preparing the working drawings, the draftsman generally has to do with the design of another. To this extent, therefore, he is not responsible for the harmony of the design with the work of other lines. He is, however, responsible, if such a conflict of design escapes him, for it will be a sure indication that he has not looked at his problem from all sides, and in the light of later and more definite information which was, perhaps, lacking when the design was first made.
In working up the shop details, the draftsman must start with the question constantly in his mind, "How do I know?" He must not fix a measurement, nor establish the position and relation to other parts of a single piece, unless he finds concrete authority in the shape of plans, specifications, or written directions for so doing. Further than this, he must determine that all the information so given is in agreement, for he will be held responsible for failure to discover such disagreements.
There is a great tendency among those young in experience to be guided by what appears to be indicated. Drawings are not always made to exact scale and the structural draftsman should never establish anything by scaling without explicit directions for so doing, and should then make a written record of what has thus been established.
One of the most important instructions which can be given a draftsman, is never to jump at conclusions. Have direct authority for all that is done and be sure your authority is not contradicted in some other place. Oral instructions should be at once written down, as when once followed, they may become a necessary factor in other work. If information is lacking or there is a conflict, however small, in any of the information which is the basis and authority for your work, refer it at once to some one above you who can carry it to the one in authority.
Shop Practice and Use of Detail Shop Drawings. When the shop details are prepared they go first, if the stock list has not previously been made, to the stock department, and a detailed bill of material required in fabrication is made. This is used either to make up the rolling lists or the lists of stock to be taken from the yard. The next step is the making of templates. These are patterns in wood of the exact size and shape of each piece, with the holes located, so that they can be used to mark out the piece itself. Formerly, the template maker did a good deal of the work now done by the draftsman, but in most shops the policy at present is to do as much in the engineering department as possible and to leave nothing to be worked out in the template room or shop.
The templates are sent to the shop and the material goes from one machine to another, being cut to length, coped, mitred, bevelled, sheared and punched as required.
When all the pieces are ready they go to the Assembly Shop and are then riveted up to form the finished piece as required by the drawings. Each piece has its letter or mark to designate it in its passage from the template room to the Assembly Shop; and when the whole piece is assembled it has a mark conforming to what is given on the setting or erection drawing, so that, when received at the job, the erectors will know where it goes.
The final work is the painting, marking, invoicing and weighing and then the shipment.
Relation of Shop Drawings. The basis of all shop details is the setting plan, or erection plan. This shows the framing of the floors and roof, generally a separate plan being required for each floor and one for the roof. This framing plan has all the necessary dimensions to fix the location of each piece, the numbers or marks designating each piece, the size of piece, and such necessary sections and notes as are required to fix the relation of the different members and to cover any special features.