Some work in the machine shop, as chipping, filing, scraping and reaming, is done by hand. Cutting threads on small bolts and pipes is frequently done at the bench, although such work is not economical.

The important tools and equipment much used in bench work are as follows, many of which are well known:

(1) Bench vise.

(2) Hammers.

(3) Cold chisels.

(4) Files.

(5) Reamers.

(6) Taps.

(7) Dies.

(8) Wrenches.

(9) Scrapers.

(10) Surface plates.

(11) Hack saw.

(12) Copper maul.

(13) Abrasive materials.

(14) Scriber.

(15) Center punch.

(a) The vise has jaws hard enough to resist wear, but not brittle enough to chip off when struck with a hammer.

(b) A reamer is used to cut a drilled hole to larger diameter. Reamers are either (1) cylindrical (called straight reamers) for enlarging holes very slightly to exact cylindrical form and given diameter, or (2) tapered for enlarging holes to a considerable degree. The end of a straight reamer must be slightly tapered to allow it to enter the hole to be reamed out. The straight reamer soon wears enough to reduce its diameter and lose its accuracy if used for any except light cutting. Expansion reamers have been devised to be sprung out as they wear.

Rose and shell reamers are made for use on lathes, drills and milling machines. A rose reamer has teeth on the end for boring out a hole, as well as teeth along the body for finishing to an exact diameter.

A

B Fig. 206. - Cold Chisels.

(c) The hack saw is very handy for sawing metal bars and rods. It consists of a thin, narrow steel saw-blade, very hard, held in a bow frame of steel by which it is kept stretched taut.

(d) The copper maul is used for such work as driving a finished shaft into the hub of a metal wheel. The soft copper saves marring the finished metal surfaces.