Modern Mechanical Engineering Vol-I

THE ESTIMATING AND COSTING OFFICES

on overall weights, on indicated horse-power, on volumetric capacity, or on
some other recognized unit of measurement.

The estimator should keep an estimate book, and it is good practice to
keep a separate book for each job, if it is of any size.

Each item should be shortly but clearly specified. The estimated
weight should be put against it, the cost of the raw material, the estimated
time of workmanship and the rate of pay, and a column should be written
up for the total cost, thus:

Piece.
Material.
Price per Ton.
Finished
Weight.
Bloom
Weight.
Material Price.
Hours.
Rate.
Workmanship.
Total.

Bloom D

rod
steel, B.S.S.
£ia
i c. 2q. 21 Ib.
2C. i q. 7lb.
£10 10
10
2S.
20$.
£n 10

An extra cost would be added, because the total cost of machining is not
merely the cost of the actual ingot plus the labour charge—there is an " over-
head charge " to be added.
Specialities of other Makers.—In the case of specialities, such as
auxiliaries and furnaces, the prices of different makers would be put down,
although only that of the successful tenderer would be carried forward to
the finished column. This would enable the work to be referred back to
expeditiously, in case of a change later on. The customer, for instance,
might prefer to pay more to get some particular make of boiler feed-pump.
Final Estimate Book.—From this book the finished estimate would
be made up, and oncost charges and profit would be added. The finished
book containing these two items is confidential, in many places the manager
reserving the care of this book to himself.
Should a contract be concluded on the basis of this estimate, the details
as they are actually finished should be entered up in an abstract book, in which
double columns should show the estimated weights, costs, &c., alongside the
actual weights and costs. Only thus can the work of the estimating office be
properly supervised and checked.
Scales of Wages, Rates of Mechanical Operations, &c.—A scale
of wages for different classes of work must be kept, also rates of speeds at
which the work can be turned out; say, in machining, the table should give
the surface which can be rough turned in a given time, also the rate for finish-
ing cuts, &c., where this process obtains. In other classes of work a piece-
work rate per 100 rivets may hold, or the rate may be so much per foot for
smithwork on angle-iron, or, in the forge, a price per hundredweight for
" light" and a price per hundredweight for " heavy " forgings. This all
implies that the estimator shall make himself thoroughly familiar with his
own shop practice. It may be necessary for him to get estimates from the
foremen, or from rate-fixers, but so far as possible this information should
be tabulated inside the estimating office, and as little reliance as possible
should be placed on shop estimates, because shop conditions are peculiarly
unfavourable to the accurate making of estimates.