1. Cutting Tool Geometry
MoManufacturingWINs Precision Machining Technology ME 100 – Measurement, Materials & Safety

2. Cutting Tool Geometry Cutting Tool geometry and how
To grind a High Speed Steel blank
For turning.
This is a depiction of a high speed
Steel blank. They come in various
Sizes usually ¼ or 5/16 square.
Definition:  The term `high speed steel' was derived from the fact that it is capable of cutting metal at a much higher rate than carbon tool steel and continues to cut and retain its hardness even when the point of the tool is heated to a low red temperature. Tungsten is the major alloying element but it is also combined with molybdenum, vanadium and cobalt in varying amounts.

3. Grinding a tool bit is
Usually done on an
Ordinary pedestal grinder
Fitted out with a rest set
At about 7 degrees. It
Doesn’t matter if the support
Is above or below the
Centerline of the wheel
As long as it’s set at 7
Degrees with respect to
a line passing through
The center of the wheel.

4. You will be
Grinding three
Sides on the
Bit. Since each
Side has two
Angles (compound
Angles) there
Are a total of
Six angles that
Have to be
Considered as
You are grinding.

5. First you will grind the “side cutting edge angle” and the “Side relief angle” Refer
To the previous page or the Machineries Handbook for angles depending on the
Material you will be cutting.
The side cutting edge angle
Provides for gradual
Entrance of the tool into the
Stock.
The side relief angle prevents
The flank of the tool from
Rubbing the stock and
Generating excessive heat.
This is one of two angles
Required in order for the tool
To cut at all.

6. Next you will grind the “Nose angle”
And “End relief angle”. The Nose angle
Allows the tool to be plunged into the
Stock and when swiveled to the left
To take light cuts close to the chuck
Or to turn to a shoulder.
The end relief Allows the tool
to be plunged into the Stock and
prevents the end of the Tool from
rubbing and generating Excessive heat.
This is the other angle that is required
In order for the tool to cut.

7. The side angle and Back rake angle
Are ground together. The side rake
Provides a keener cutting edge.
The back rake permits the chips to
Flow away from the point of the tool

8. Grind a radius on the edge between the side (side #1) and nose (side #2). The radius
you use Will depend on the purpose of the bit. The larger the radius the better the
Surface finish but you also run the risk of machine chatter. Generally use less
Radius on lighter machines.
Carbide tools and even rotary tools use
Different angles but the principals are the
Same.
When working around grinders it is an absolute necessity to wear EYE PROTECTION. Grinding debris is thrown out at high velocities and can damage not only eyes, but also expensive glasses. Wear safety glasses or a full face shield.

9. Tool bits can be ground for specific applications
Tool bits can be ground for specific applications. The description above was for
Grinding a general purpose, right hand, tool bit. The images below show some
Of the other varieties.
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