CHAPTER XXVIII. 

 ESTIMATE OF WEIGHT AND COST. 



ESTIMATE OF WEIGHT. The contract drawings for mill 

 buildings are usually general drawings about like those in Fig. 167 and 

 Fig. 1 68, in which the main members and the outline of the building 

 are shown, together with enough sketch details to enable the detailer 

 to properly detail the work. In making an estimate of weight from 

 general drawings it is necessary that the estimater be familiar with the 

 style of the details in use at the shop, and with the per cent of the main 

 members that it is necessary to add, to provide for details and get the 

 total shipping weight of the structure. There are two methods of al- 

 lowing for details : ( I )to add the proper per cent for details to the weight 

 of each main member in the structure, and (2) to add a per cent for 

 details to the total weight of the main members in the structure. The 

 first method is the safest one to follow, although the second gives good 

 results when used by an experienced man. The best way to obtain 

 data on the per cents of details of different members in buildings and 

 other structures is to make detailed estimates from the shop drawings. 

 By checking these data with the actual shipping weights, the engineer 

 will soon have information that will be invaluable to him. Second 

 hand data on estimating are of comparatively little value for the rea- 

 son that the conditions under which they hold good are rarely noted, 

 and it is better that the novice work out his own data and depend on 

 his own resources, at least until he has developed his estimating sense. 

 In short the only way to learn to estimate, is to estimate. 



The method of making estimates will be illustrated by making an 

 estimate from the working drawings of a steel transformer building, 

 the general plans of which are shown in Figs. 167 and 168. The 



