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Full text of "Modern Mechanical Engineering Vol-I"

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The Estimating and Costing Offices
Costing System.—Large modern businesses keep the estimating
department distinct from both the design and working drawing offices, but,
of course, with absolutely free access to the working drawings, sketches,
orders, and data-books of the drawing office, and with access to the books
of the costing department. The costing department is sometimes run as
a branch of the estimating department. A good costing system is the founda-
tion stone of successful estimating. To neglect this important section—
and it is shamefully neglected in all but comparatively few firms—is to run
very serious and quite unnecessary risks. " The working of this section
would demand a monograph on itself to describe it: it is taken for granted
Scanty Material for First Estimates*—In estimating for new
contracts, one is usually given only a few general outlines in the first case;
indeed, there may be three or four tentative offers before the definite con-
tract is fixed. This is very noticeable in large ship contracts, where the
shipowners have to study carefully a great number of problems before
coming to a definite decision, such as the quantity and kind of trade anti-
cipated, dock accommodation, fuelling facilities on the proposed route,
repairing facilities, tides, and consequently most economical speeds, &c.
Many tentative schemes must be submitted, and it may take months before
a satisfactory conclusion is reached.
This sort of thing makes it essential that the estimator should enter
against each estimate the date on which it is made, so that, by the aid of
his " material " charts, he may be able to make the necessary corrections when
the final order comes along. For instance, there may be one or two pounds
of an increase per ton of steel between his first estimate and the time when
the contract is fixed. On a ship, say, in which there may be several thousand
tons of steel this makes a considerable difference in price.
Tendency of Market Prices.—It is usual, unless the firm's accountant
or buyer is convinced of an impending fall in the market, to fix the sub-
contracts as early as possible, both for reasons of cheapness and to secure
priority of supply. It may happen that it is impossible to be sure of an
accurate estimate, particularly if the work be absolutely fresh, and if no
particulars be available for a similar class of contract. This is not an unusual
circumstance in bridge-building, say, or in the design of a very large and
speedy liner. In this case it is usual to leave the estimate a little " lucky ",
but discrimination must be used in this matter, and attention paid to the
" tendency " of the market, whether moving up or down.
Register of Weights of Previous Jobs.—A very important item, if
correct estimates are to be forthcoming, is that the register of weights of