EN
13
Thicker Drills
When grinding thicker drills (over approx. 10 mm or
3/8
"
) for the first time, quite a
lot material needs to be ground away to achieve the right secondary bevels. If you
start by grinding away the heel on a bench grinder, you can save time. The heel has
no influence on the function of the drill.
Grind away the heel
on a bench grinder.
The heel
H
, is ground
away.
Finished ground drill
on the Tormek machine.
P
S
H
Some Advice and Tips
Heavily Worn Drills
If the drill is heavily worn, quite a lot material needs to be ground away to obtain
new cutting edges. In this case you need to mount the drill turned anticlockwise
towards the slanting lines. How much depends upon the degree of wear. As the drill
is ground the cutting edges change direction. When the grinding is completed, the
edges should be parallel to the horizontal lines.
Mount a heavily worn drill turned
anticlockwise.
When the grinding is finished the
primary facets
P
should be parallel
to the horizontal lines.
Continue grinding until the
primary facets
P
are paral-
lel to the horizontal lines.
Mount the drill so that the
edges
E
are parallel to the
slanting lines.
After a few minutes the pri-
mary facets
P
are ground.
It takes approx. 4 minutes
for a 10 mm (
3/8
") drill.
�
�
Broken Drills
When mounting these are turned anticlockwise so that the edges
E
are parallel to
the slanting lines. The primary facets are developing during the grinding and when
the grinding is finished they should be parallel to the horizontal lines.
