Echo 72928 Owners Manual v.4 - Manual (Page 21)

18
Figure 3.2
45 °°°°°
0.38
Sharpening
Edges
Figure 3.1
S E C T I O N 3
WARNING: Before inspecting or servicing any part
of the machine, shut off the engine, and make sure
all moving parts have come to a complete stop. The chip-
ping blades are sharp! Use care when working on ma-
chine to avoid injury.
WARNING: The rotor assembly has a lock mecha-
nism. When working on the rotor assembly, use the
lock mechanism at all times. Remove the plastic bearing
cover beside the chipper chute. There is a hole in the rotor
shaft and a matching hole in the bracket mounted to the
rotor bearing front side. Install a punch through the rotor
shaft and bracket to lock the rotor in place.
Check the engine oil, and change the oil and filter as rec-
ommended in the manual. Service and replace the air
cleaner as recommended.
3.1 Sharpening Chipper Blades
The chipper blades will eventually become dull, making
chipping difficult. The chipper blades are two edged. When
the first edge dulls, flip the blade to use the sharp second
edge. After both edges are dull, sharpen the chipper blades.
It is recommended that the chipper blades are sharpened
every 5-15 hours of chipper operation. To remove the
chipping blades for sharpening:
1. Remove the two 3/8 inch retaining bolts holding ac-
cess cover to main frame assembly.
2. Tilt access cover over to allow rotor access. Rotate
the rotor so that the bolts holding a chipping blade are
most accessible.
3. Remove the two allen head bolts holding the blade
itself. Repeat for all four blades. The four chipping
blades have two edges per blade and can be reversed
one time each before sharpening. If both sides have
not been used, remove and reverse the chipping blades.
Reinstall chipping blades and proceed with chipping.
To grind the angled edge of the chipping blade to 45 degrees
(see figure 3.1): Grind the blades on a slow-speed wet
grinder if possible, or have them sharpened by a
professional. If you use a bench grinder, be careful when
grinding so that the blade material does not get too hot and
change color–this will remove the blade's special heat
treated properties.
Use short grinding times and cool with water. Try to remove
an equal amount off each blade to maintain balance.
Replace the chipping blades and tighten bolts to 75 ft. lbs.
Close cover and replace bolts.
3.1.1 Chipping Blade Sharpening Tips
Poor chipping performance is usually a result of dull chipping
blades. If your chipper's performance has decreased,
check for the following symptoms:
• Severe vibration when feeding material into the chip-
per.
• Small diameter branches do not self-feed.
• Chips discharge unevenly or have stringy tails–espe-
cially when chipping green branches.
Before you sharpen the chipping blades, check for
permanent damage. Replace the blade if:
• The blade is cracked (especially around the bolt holes)
or the edges are too deeply chipped to be ground
smooth.