CHAPTER X.

=CUTTING TOOLS FOR LATHES.=

=Principles= governing the shapes of lathe tools 254 =Diamond-pointed=, or front tool 254 =Principles= governing use of tools 254 Front rake and clearance of front tools 254 Influence of the height of a tool upon its clearance and keenness 255 Tools with side rake in various directions 256 The effect of side rake 256 The angle of clearance in lathe tools 257 Variation of clearance from different rates of feed and diameters of work 257 =Round-nosed= tools 258 =Utmost Duty= of cutting tools 258 Judging the quantity of the tool from the shape of its cutting 259 =Square-nosed= tools 260 The height of lathe tools 260 Side tools for lathe work 261 Cutting-off or grooving tools 262 Facing tools or knife tools 262 Spring tools 263 =Brass Work=, front tools for 264 Side tools for 264 =Threading= tools 264 Internal threading tools 264 The length of threading tools 265 The level of threading tools 265 Gauges for threading tools 266 Setting threading tools 266 Circular threading tools 267 Threading tool holders 267 =Chasers= 268 Chaser holders 268 Setting chasers 268 =Square Threads=, clearance of tools for 269 Diameter at the roots of threads 269 Cutting coarse pitch square threads 269 Dies for finishing square threads 269 =Tool Holders= for outside work 270 For circular cutters 272 Swiveled 273 Combined tool holders and cutting-off tools 273 =Power Required= to drive cutting tools 273