This Drill Point Sharpening Gage is offered complimentary in the Engineers Black Book
- USA Edition (Inch) and 2nd Edition (Metric) Versions. The Engineers Black Book - 3rd Edition INCH version is not supplied with this Gage and it can be purchased seperately.
Drill Point Sharpening Methodology
Step 1 // Hints for Hand Grinding Twist Drills
Procedure: The left hand thumb and
forefinger is used as a pivot as illustrated
and the back of the drill is held with
the right hand and forefinger and rotated
in a clockwise direction advancing the
drill into the grinding wheel.
Points to Note:
Keep the drill point constantly sharp
Avoid excessive grinding pressures
Avoid overheating the drill point
Avoid sudden cooling of the drill point
Use copious supply of coolant
The periphery of the wheel should be
used for roughing-out of the drill point
if much metal must be ground away
The side of the wheel should
be used for finishing
Step 2 // Line Drill up with Gage against desired Tip Angle
The DRILL POINT SHARPENING GAGE
is the tool most frequently used to
check the drill point during the
Step 3 // Drill Test and the Effects of incorrect grinding of the Drill Point
To test whether a drill has been properly sharpened,
drill a hole in soft material and observe the chip formation.
When properly sharpened, the chips will come out of the
flutes in curled spirals of equal length
Incorrect grinding causes the drill bit to run out of true, producing oversized and often, out-of-round holes.
This puts severe strain on the drill bit causing rapid wear and premature drill failure.
Lips of EQUAL lengths but UNEQUAL angles
Lips of UNEQUAL lengths but EQUAL angles
Lips of UNEQUAL lengths
and UNEQUAL angles
Size - Overall 80.00mm x 100.00mm 3.149" Inches x 3.936" Inches