USE OF FORM TOOLS
In lathe work, form tools are used for form turning, producing short tapers, thread chasing, and other
applications. If a form tool is to reproduce the special contour of its cutting edge on the work piece
surface, it is important that the cutting edge should be adjusted so that it is at the same height as the
rotational axis of the work piece. This is known as adjusting the cutting edge on center. If a form tool is
set above or below center, a contour differing from that of the cutting edge will be produced on the
surface of the work piece. For the feed, a form tool is moved into the work piece with the cross slide.
PARTING OR CUTTING OFF
Parting is the operation of severing a work piece from a bar. It is done with a narrow cutting tool, which
cuts only at its end. A parting tool should be adjusted so that its cutting edge is on center if it is to cut to
the center of a bar. It should also be set so that no rubbing or cutting will occur along its sides.
GROOVING
A groove can be produced with a parting tool or with a form tool.
KNURLING
Making a raised diamond-shaped pattern on the cylindrical surface 01 a work piece is known as
"knurling." Surfaces are often knurled so that they may be more easily gripped with the fingers or by
hand. A knurling tool has two serrated hardened-steel rollers with the serrations slanted at 4-5 degrees
from the horizontal.
The serrations of the roller are slanted at 90 degrees from those of the other roller. Both rollers are