1 5.
GRINDING OF THE DRILLS
1 3
The prism, with the well aligned drill is slipped on to the prism swing pin and revolved in
front of the grinding wheel (page 5, No. 4). Simultaniously move the drill feed carriage
towards the grinding wheel by means of the knurled nut (page 5, No. 9) until one side of
the prism is well formed.
Note the scale mark on the nut (e. g. scale mark 5). Move backward the feed carriage by
2 to 3 scale marks closer to the grinding wheel.
The drill in this position is swiveled until no further formation of the sparks are visisble.
In the order to achieve the best possible cutting edge symmetry, the prism is reversed
again by 1 80° without any alteration of the position of the drill feed carriage. The other
side is ground until no more spark are visisble.
ATTENTION!
In order to prevent temper of anneal, please always work with low
feeding grade.
Wear your safety glasses!
Grind the cutting edges of the first step same as standard
twist drills. The cutting edges of the second step are
likewise aligned in parallel with the indicated marks of
adjustment (see chapter "Alignment and adjustment of
drills"). The drill inside the prism is then pushed forward
until the second step passes by the grinding wheel and
touches the grinding wheel (Picture).
Using the knurled nuts (7) and (9) you can do the fine
adjustment of the drill to the grinding wheel. Thereafter
you resharpen the cutting edges by way of the reversal of
the prism as described before for standard twist drills.
1 6.
STEP DRILLS