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Pre-raked outside blades like left in Figure 4 loose some seating surface on
the 30° bottom seating surface. In case of blades without a side rake angle like
shown at the right side of Figure 4, seating properties and blade stiffness are
optimal. Blades without the pre-raked front face are correctly called “zero rake
blades”.

22.3 Tooth Forming Blade Contour and its Measurement

Cutting Edge, Clearance Side and Blade Tip specifications are defined in
Figure 5. The Top Slope Angle with relief away from the cutting-edge tip cor-
ner as shown in Figure 5 is defined as positive. A positive top slope protects
the clearance edge. The Pressure Angle for blade grinding is defined at the
blade reference point which has a distance of the Blade Dedendum from the
horizontal coordinate axis in Figure 5. The horizontal coordinate axis contacts
the point where the top slope and the extension of the cutting edge (straight or
curved) intersect. This point does not physically exist.

Figure 5: Specific features of tooth forming contour

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