Now the 4-facet shape will start to
develop, but the secondary facets S
need to be ground further so that they
meet in the centre and form a point.
Grind the two secondary bevels alternately until the lug (11) touches the stop
nut S on both sides. Make the final grindings carefully and check that the facets
are symmetrical and form a point.
Feed the nut S a bit further. Try with ¼
of a turn. One turn is equal to 0.5 mm
(0.02").
This is how a ground drill should look like. The secondary facets S meet the primary
facets P in the centre. The flat chisel edge has been shaped to a point, F.
Continue grinding until the lug (11)
touches the stop nut S.
Turn the drill holder 180° and grind the
other secondary facet in the same way.
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