Maintenance; Sharpening The Saw Chain - Makita DUC252 Instruction Manual

Carrying tool (Fig. 33)
Always remove the battery cartridge from the tool and
overlap the guide bar with the guide bar cover before
carrying the tool. Also cover the battery cartridge with the
battery cover.

MAINTENANCE

CAUTION:
• Always be sure that the tool is switched off and the
battery cartridge is removed before attempting to
perform inspection or maintenance.
• Always wear gloves when performing any inspection or
maintenance.
• Never use gasoline, benzine, thinner, alcohol or the
like. Discoloration, deformation or cracks may result.

Sharpening the saw chain

CAUTION:
• Always remove the battery cartridge and wear safety
gloves when performing work on the saw chain.
Sharpen the saw chain when: (Fig. 34)
– Mealy sawdust is produced when damp wood is cut;
– The chain penetrates the wood with difficulty, even
when heavy pressure is applied;
– The cutting edge is obviously damaged;
– The saw pulls to the left or right in the wood. The
reason for this behaviour is uneven sharpening of the
saw chain, or damage to one side only.
Sharpen the saw chain frequently, but remove only a
little material each time.
Two or three strokes with a file are usually sufficient for
routine resharpening. When the saw chain has been
resharpened several times, have it sharpened in a
MAKITA specialist repair shop.
Sharpening criteria: (Fig. 35)
– All cutter length must be equal. Cutters of differing
length prevent the chain from running smoothly, and
may cause the chain to break.
– Do not sharpen the chain once a minimum cutter length
of 3 mm has been reached. A new chain must then be
fitted.
– The chip thickness is determined by the distance
between the depth gauge (round nose) and the cutting
edge.
– The best cutting results are obtained with following
distance between cutting edge and depth gauge.
Chain blade 90PX: 0.5 mm
Chain blade 91PX: 0.65 mm
Chain blade 25AP: 0.65 mm
WARNING:
• An excessive distance increases the risk of kick-back.
– The sharpening angle of 30° must be the same on all
cutters. Differences in angle cause the chain to run
roughly and unevenly, accelerate wear, and lead to
chain breaks.
– The side plate angle of the cutter is determined by the
depth of penetration of the round file. If the specified
file is used properly, the correct side plate angle is
produced automatically.
– Side plate angle for each saw chain are as follows:
Chain blade 90PX: 75°
16
Chain blade 91PX: 80°
Chain blade 25AP: 85° (Fig. 36)
File and file guiding
– Use a special round file (optional accessory) for saw
chains to sharpen the chain. Normal round files are not
suitable.
– Diameter of the round file for each saw chain is as
follows:
Chain blade 90PX: 4.5 mm
Chain blade 91PX: 4.0 mm
Chain blade 25AP: 4.0 mm
– The file should only engage the cutter on the forward
stroke. Lift the file off the cutter on the return stroke.
– Sharpen the shortest cutter first. Then the length of this
shortest cutter becomes the standard for all other
cutters on the saw chain.
– Guide the file as shown in the figure. (Fig. 37)
– The file can be guided more easily if a file holder
(optional accessory) is employed. The file holder has
markings for the correct sharpening angle of 30° (align
the markings parallel to the saw chain) and limits the
depth of penetration (to 4/5 of the file diameter).
(Fig. 38)
– After sharpening the chain, check the height of the
depth gauge using the chain gauge tool (optional
accessory). (Fig. 39)
– Remove any projecting material, however small, with a
special flat file (optional accessory).
– Round off the front of the depth gauge again.
Cleaning guide bar (Fig. 40)
Chips and sawdust will build up in the guide bar groove,
clogging it and impairing oil flow. Always clean out the
chips and sawdust when sharpening or replacing the saw
chain.
Cleaning the oil discharge hole
Small dust or particles may be built up in the oil discharge
hole during operation.
Small dust or particles built up in the oil discharge hole
may impair the oil discharge flow and cause an insufficient
lubrication on the whole saw chain.
When a poor chain oil delivery occurs at the top of guide
bar, clean the oil discharge hole as follows.
Remove the battery cartridge from the tool.
Remove the sprocket cover and saw chain from the tool.
(Refer to the section titled "Removing or installing saw
chain".)
Remove the small dust or particles using a slotted
screwdriver with a slender shaft or the like. (Fig. 41)
Insert the battery cartridge into the tool.
Pull the switch trigger to flow built-up dust or particles off
the oil discharge hole by discharging chain oil.
Remove the battery cartridge from the tool.
Reinstall the sprocket cover and saw chain on the tool.
Replacing the sprocket (Fig. 42)
Before fitting a new saw chain, check the condition of the
sprocket.
CAUTION:
• A worn sprocket will damage a new saw chain. Have
the sprocket replaced in this case. The sprocket needs