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.
The following are the general divisions of material:
(a). Plain beams and channels.
(b). Beams and channels, punched two or more sizes of holes in web.
(d). Beams and channels, punched in web and flanges.
(c). Framed beams and channels.
(f.) Framed and coped beams and channels.
II. Beams and channels 18 inches and above.
The above divisions apply also to these sizes of beams and channels.
There is an extra charge for all beams and channels over 15 inches deep, therefore these sizes must be separated.
Further, all the other shapes must be kept separated from beams and classified by themselves in a manner similar to the division of beams. For instance, the members composing the columns as plates, channels, angles, zee bars, etc., are each kept by themselves.
All connections of beams to girders and columns are charged at a different price from ordinary angles or plates, and must therefore be figured separately. In a like manner tie rods, anchors, beam plates, column bases, separators and bolts all are classified separately.
It is evident that these different divisions cannot be made at the time the schedule is taken from the plans, and it is customary to take off the material in order as it appears on the plans, and by some system of marking designate the class to which the piece belongs. The separation is then made when the weights are calculated and the quantities are being totaled.
It is also evident that such things as separators, framing, connections, splices, and other details cannot be taken directly from the plans, but must be calculated largely by the judgment of the estimator. He must be able to see just what character of connection is required in order to classify correctly his material as he takes it off.
Effect of Changes. Changes in details must sometimes be made from causes beyond the control of the draftsman. A change in the location of certain members, or the general arrangement at a certain point, may make it necessary to revise drawings already made and perhaps sent to the shop. In such cases, the drawing generally bears the same number and is marked revised. In case additional sheets must be prepared, of course new numbers are given to them. In sending out a revised drawing, instructions should be sent to have the original sheets returned in order that they may all be destroyed and thus remove all liability of the material being made up by the old drawings. Revising details already completed and checked are fruitful sources of errors. Unless the greatest care is exercised, the changes made will affect the relations to some other members and the details of some other portions of the work not at first apparent. The draftsman should have this point always in mind and review all possible connections to other work when revising any details.
Use of Details in the Work. The detail drawings must frequently be used in determining features of other work and in laying out such work, and for this purpose the detail drawings should contain information enough to establish the relation of the steel to such working lines as finished floor levels, datum line, ashlar line, party line, and such other lines used in the general drawings to establish the relations of the different parts of the work.