(3) Place proper size insert counterbore cutter on arbor.
(4) Slide ST-257 valve seat insert tool cutter drive shaft over arbor and mate slot in cutter with tangs on shaft.
(5) Secure insert tool to head with washer and capscrew.
(6) Loosen feed engaging knob and loosen setscrew on feed depth knob.
(7) Rotate feed depth knob to lower cutter drive shaft until shaft is fully engaged with slot in cutter.
(8) Using new seat insert as depth gage, place insert and 0.006 in. (0.1524 mm) feeler gage between top of
tool housing and feed depth knob.
(9) This sets tool to bore to width of insert plus 0.006 in. (0.1524 mm) to permit staking of insert to head.
(10) Tighten feed depth knob setscrew.
(11) Remove insert and feeler gage.
(12) Tighten feed engaging knob. Automatic feed is now engaged.
(13) Apply cutting oil to cutter.
(14) Secure insert tool drive shaft in drill chuck.
(15) Start drill and cut counterbore.