Skip to main content

Full text of "Modern Mechanical Engineering Vol-I"

See other formats

sides. One long, wide bench with several vices is reserved for the larger
patterns when the work is of such a character as to require them. Machines
are arranged along one side or one end of the shop, in close proximity for
convenience of driving and of operation. The circular saw and the planing-
machine must have unobstructed spaces at front and rear for the movement
of boards. The most suitable drive is a gas-engine or an electric motor,
either of them driving a length of shaft from which the machines are driven.
If metal pattern-work is done, this engages a separate department, or is
relegated to another building. When large patterns are constructed, large
doors are required at one end of the shop. Whether the shop shall occupy
a ground floor or an upper story is a matter of no importance. A ridge roof
with north light is desirable, or, having a ceiling, side windows must be of
sufficient area. The shop should be heated with hot water, unless a regular
hot air and ventilating system is installed in the works, which may include
the pattern-shop.
The timber should be stored adjacent to the shop. It is stripped during
seasoning, but may be laid edgewise when ready for use. As timber is
expensive, economy can be practised by storing all odds and ends, which are
numerous in pattern-work, on racks at one end of the shop. The selection
of suitable fragments will often save the expense of cutting into a board.
Core prints are turned in quantities for stock by the apprentices. Some are
nailed on patterns, but a fair proportion are turned with studs of some
standard diameter to go on bosses for gear wheels and pulleys. Wooden
dowels may be stocked, but the metal kinds are more durable. Wooden
fillets, hollows, or angles are required for all patterns except the roughest,
tut those of leather are supplied to the trade. Pattern letters of various sizes
and shapes are made in lead, tin, and brass, but these are better bought.                          !
Rapping plates to suit all patterns are purchased.    All these are kept in the                          • {
shop stores.
Method of Working.—The organization of the machine-shop is not
represented in the pattern-shop.. Methods have been modified by the
introduction of the machines just now described. The result is that much
laborious hand-work formerly done on the bench is performed much more                          {
expeditiously on machines. All the hands are trained craftsmen, who have
served a lengthy apprenticeship, and who work under the direction of an
experienced foreman. And although the practice in the large shops is to
keep certain men or groups occupied with definite tasks, these are men with
a general training, who have drifted into specialization.
Men are paid by time in most shops. The variable character of the work
done, the fact that the greater portion of it is handicraft, that alterations are
sometimes seen to be desirable during its progress, and that one foreman is
easily able to keep the entire shop under observation, are causes that favour
payment by time rather than by the piece.
The method of constructing a pattern is settled by the foreman. When
uncertainty exists as to the selection of the best among alternative methods
of moulding, it is well to discuss the matter with the foreman of the foundry.