Magna-Matic MAG-8000 Series, Operating Instructions Manual, Page: 26 / 28

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25
Rotary Mower Blade Tip Geometry
Consider the following if you sharpen rotary lawn
mower blades.
Description Diagram
Relief 1:
Top View - built
into the blade.
(generally 2-5
degrees)
1
Relief 2:
End View - To be
re-sharpened.
(generally 60
degrees)
2
Relief 3:
End View - built
into the blade.
Generally 0˚
3
Optimum
Top View:
Worn Blade
Edge
Worn away bottom
surface at tip, as
shown, is a sign
of poor blade
maintenance. The
blade will tear the
grass, resulting
in a poor looking
lawn.
NOT ACCEPTABLE
The tip of the blade
does the majority
of the cutting. To
produce a tip, three
reliefs are necessary.
Think of a lawn
mower blade as a
circular saw with
only “TWO TEETH”
and remember the
tip does the majority
of the cutting work.
Repetitive observa -
tion of worn cutting
edges shows that
the first one inch
does the majority of
the cutting work.
IMPORTANT
NOTES:
Attempting to
straighten a lawn
mower blade may
cause fractures in
the hardened steel
of the blade and
shall be avoided.
Anytime you alter
the steel of the
blade due to re-
sharpening, wear or
build-up, you change
the balance.