27
7-1. Sharpening the saw chain
CAUTION: Before doing any work on the guide
(see
7-6 “Replacing the spark plug”). Always wear
protective gloves!
(Fig. 59)
The chain needs sharpening when:
The sawdust produced when sawing damp wood looks like
wood our.
The chain penetrates the wood only under great pressure.
The cutting edge is visibly damaged.
The saw is pulled to the left or right when sawing. This is
caused by uneven sharpening of the chain.
Important: Sharpen frequently, but without removing too
much metal!
Generally, 2 or 3 strokes of the le will be enough.
Have the chain resharpened at a service center when you
have already sharpened it yourself several times.
Proper sharpening:
CAUTION: Use only chains and guide bars designed for
(Fig. 60)
All cutters must be of the same length (dimension a). Cutters
with dierent lengths result in rough running of the chain and
can cause cracks in the chain.
The minimum cutter length: 3 mm. Do not resharpen the chain
when the minimum cutter length has been reached; at this
point, the chain must be replaced (see 10 “Extract from the
spare parts list” and 7-4 “Replacing the saw chain”).
The depth of the cut is determined by the dierence in height
between the depth limiter (round nose) and the cutting edge.
The best results are obtained with a depth-limiter depth of
0.64 mm (.025”).
CAUTION: Excessive depth increases
the risk of kickback!
(Fig. 61)
The sharpening angle (α) must be identical for all cutters!
30° for chain type 092 (91VG), 492 (91PX), 290 (90SG),
291 (90PX)
The teeth will have the proper angle (b) automatically if the
proper round le is used.
80° for chain type 092 (91VG), 492 (91PX)
75° for chain type 290 (90SG), 291 (90PX)
Dierent angles result in a roughly, irregularly running chain,
increase wear and tear and cause chain beakage.
Files and how to work with them
Use a special saw chain round le for sharpening. Standard
round les are unsuitable. See 10 “Extract from the spare parts
list”.
Type 092 (91VG), 492 (91PX): Saw chain round le, dia. 4.0 mm
Type 290 (90SG), 291 (90PX): Saw chain round le, dia. 4.5 mm.
(Fig. 62)
The le should cut only when pushed forwards (arrow). Lift the
le when leading it backwards.
First sharpen the shortest cutter. The length of this cutter is
then the standard for all other cutters of the chain.
New saw teeth must be led to the exact same shape as the
used teeth, including on their running surfaces.
File depending on chain type (90° or 10° to the guide bar).
(Fig. 63)
A le holder makes le guidance easier. It is marked for the
correct sharpening angle of:
α = 30°
(keep the marks parallel with the chain when ling, see
illustration) and limits the cut depth to the correct 4/5 of the le
diameter.
(Fig. 64)
After having sharpened the chain, the height of the depth
limiter must be checked by means of a chain gauge. See 10
“Extract from the spare parts list”.
Correct even the smallest excess height with a special at
le (1). See 10 “Extract from the spare parts list”.
Round o the front of the depth limiter (2).
7-2. Cleaning the inside of the sprocket guard
CAUTION: Before doing any work on the guide bar or
(see 7-6 “Replacing the spark plug”).
Always wear protective gloves!
CAUTION: Start the chain saw only after having
assembled it completely and inspected.
(Fig. 65)
Remove the sprocket guard (1) (see 6 “PUTTING INTO
OPERATION” for the correct model) and clean out the interior
with a brush.
Remove the chain (2) and guide bar (3).
NOTE:
Make sure there are no residues or foreign matter remaining in
the oil guide groove (4) or on the chain tensioner (5).
To install the guide bar, saw chain, and sprocket guard, see 6
“PUTTING INTO OPERATION” for the correct model.
NOTE:
The chain brake is a very important safety device and
like any other component subject to normal wear and
tear.
Regular inspection and maintenance are important for
your own safety and must be done by a DOLMAR service
center.
SERVICE
7. MAINTENANCE
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