Fig. 1004.
The second method of increasing the efficiency of a chaser is to grind the top face at an angle as from a to b in [Fig. 1004], and set it so that the last tooth b is at or a little above the work axis d. This causes the last tooth b to stand sufficiently nearer the work axis than the other teeth to enable it to take a light scraping cut, producing a smooth cut, because the duty on the last tooth being light it preserves its cutting edge, and therefore its form.
Chasers are often in shops, doing general work, formed in one piece in the same way as an ordinary tool, but it is preferable to use short chasers and secure them in holders.
Fig. 1005.
