Regrinding Instructions for Gun Drill N-8 & Half Round Drill HA-1:
- Position horizontal register at +30º , (half round drills at +20º), vertical register at +12º. Grind until all wear is removed.
- Position horizontal register at +29º, (half round drills at +19º), vertical register at +20º. Grind to establish the primary relief width of approximately 5% of the diameter.
- Position horizontal register at -20º, (half round drill at -15º), vertical register at +12º. Grind to establish the point position width of drill diameter. (Dia./4).
- Position horizontal register at 0º, vertical register at +25º. Grind front clearance until the triangle created reaches the rear edge of the primary relief.
- For gun drill only. Position horizontal register at -25º, vertical register at -12º. Grind until the triangle formed reaches the center of the tip "V".
- Remove drill and freehand a periphery chamfer around the radial surface at approximately 20º, stopping just short of the primary relief.
Either style of regrinding fixture can be used to resharpen half round and/or single flute drills, or take advantage of Sterling Gun Drills' resharpening service with fast turnaround. Please also view the Regrinding Section.
TWINMASTER™ - Regrinding Information
TWINMASTER™ two flute drills can be resharpened many times, maintaining optimum performance. Used up drills or damaged drills with good tubes can be retipped. The grind can be reproduced on universal tool and cutter grinding equipment; this diagram shows basic geometries. Sterling Gun Drills offers regrinding services with next day turnaround.
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