CHAPTER XII.

=EXAMPLES IN LATHE WORK.=

=Technical Terms= used in the work 296 =Lathe Centres= 296 Devices for truing 297 Tools for testing the truth of, for fine work 298 Shapes of, for light and heavy work 299 =Centre Drilling=, attachment for lathes 300 The error induced by straightening work after 300 Machine 300 Combined centre-drill and countersink 300 Countersink with adjustable drill 300 Centring square 300 Centre-punch 300 Centre-punch guide 301 Centring work with the scribing block 301 Finding the centre of very rough work 301 Centre-drill chuck 302 The proper form of countersink for lathe work 302 Countersinks for lathe work 302 Various forms of square centres 303 The advantage of the square centre for countersinking 303 Novel form of countersink for hardened work 303 Chucks for centre-drilling and countersinking 303 Recentring turned work 304 =Straightening Work.= Straightening machine for bar iron 304 Hand device for straightening lathe work 305 Chuck for straightening wire 305 =Cutting Rods= into small pieces of exact length, tools for 305 =Roughing cuts=, the change of shape of work that occurs from removing the surface by 306 Feeds for 306 Rates of feed for 307 =Finishing Work=, the position of the tool for 307 Finishing cast-iron with water 307 Specks in finished cast-iron work 307 Scrapers for finishing cast-iron work 307 Method of polishing lathe work 308 Filing lathe work 308 The use of emery paper on lathe work 308 The direction of tool feed in finishing long work 309 Forms of laps for finishing gauges or other cylindrical lathe work 310 Forms of laps for finishing internal work 311 Grinding and polishing clamps for lathe work 311 Burnishing lathe work 311 =Taper Work=, turning 312 The wear of the centres of 312 Setting over the tailstock to turn 312 Gauge for setting over 313 Fitting 313 Grinding 313 The order of procedure in turning 313 The influence of the height of the tool in producing true 314 =Special Forms.= Curved work 314, 315 Standard gauges for taper work 316 Methods of turning an eccentric 317 Turning a cylinder cover 318 Turning pulleys 318 Chucking device for pulleys 318 =Cutting Screws= in the lathe 319 The arrangement of the change gears 319 The intermediate wheels 319 The compounded gears 320 Finding the change wheels to cut a given thread 320 Finding the change wheels for a lathe whose gears are compounded 321 Finding the change gears for cutting fractional pitches 321 To find what pitch of thread the wheels already on the lathe will cut 322 Cutting left-hand threads 322 Cutting double threads 322 Cutting screws whose pitches are given in the terms of the metric system 322 Cutting threads on taper work 323 Errors in cutting threads on taper work 324