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Craftsman 351.226121 Operator's Manual page 6

7 x 12" band saw
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• Thesealbetween thegearbox andthecoverplateis
a gasket ( KeyNo.14).Ifcoverplateis removed, the
surface shouldbecleaned anda newgasket s hould
beapplied.
• Afterthefirstfiftyhoursofuse,thegearboxshould
bedrained andrefilled withindustrial gearoil.
BLADE
GUIDES
Band saw blade has to be twisted relative to the plane
in which it rotates. Blade must be properly positioned
relative to the workbed.
Blade guides hold the cutting portion of the blade in a
plane which is perpendicular to both the workbed and
the stationary vise and keep the blade in line with its
natural path around the blade wheels.
Inner guide bearings on the upper and lower guide assem-
blies keep the blade in line with the blade wheels. Outer
guide bearings keep the blade against the inner bearings.
Entire guide assembly is positioned at the factory to
produce the proper twist and should not need adjust-
ment, however, the position of blade guides should be
checked often.
NOTE: Since the blade position is related to both table
and the vise jaws, the relative position of the jaw to the
table is important. When assembled, the stationary jaw
must be perpendicular
to the surface of the workbed.
CHECKING
BLADE
GUIDES
Refer to Figure 10, pages 16.
Check that the blade teeth are perpendicular
to the
machined surface of the base.
Spread the blade guides as far apart as possible.
Check that vise jaws are parallel and set for 90 ° cutoff.
Position the vise jaws to have the maximum separa-
tion that will not interfere with the blade guides.
With the head in horizontal position, use a square
against face of rear vise jaw and check that jaw is
90 ° to the side of blade.
Check that the blade is in line with tracking and drive
wheels (Key Nos. 44 and 52).
Raise the head.
Look straight on at the cutting edge of the blade.
Make sure that the blade sides are parallel to the
sides of the bearings.
Make sure the bearings (Key No. 6) touch the blades
and can still be rotated by hand.
ADJUSTING
GUIDE BEARINGS
Refer to Figure 10, page 16.
If the blade is not perpendicular
to the base or not in
line with the blade wheels, adjustment is necessary.
NOTE: There should be .000-.001" clearance between
the blade and the guide bearings.
The guide bearings are adjusted using an eccentric
location system. The inner guide bearings are fixed and
cannot be adjusted. The outer guide bearings are
mounted to eccentric shafts (Key No. 5) and can be
adjusted.
Loosen hex nuts (Key No. 15) with a wrench. Rotate
the eccentric shaft to locate bearings in desired
positions.
Maintain eccentric shaft position and tighten hex nuts.
CHECKING
THRUST
BEARINGS
Refer to Figure 10, page 16.
The thrust bearings (Key No. 6) should be .003-.005"
(average thickness of a piece of paper) away from back
of blade. The thrust bearings are adjusted by moving
the guide bracket.
ADJUSTING
GUIDE BRACKETS
Refer to Figure 10, page 16.
If the bearings are positioned properly and the blade
is not square, one or both blade guide brackets (Key
Nos. 3 and 23) must be adjusted.
Loosen the socket head bolts (Key No. 11).
Adjust the bracket to the correct position.
Tighten the socket head bolts.
Check the guide bearings. Repositioning the blade
guide bracket can alter the previous adjustments.
Readjust if necessary.
BLADE
SELECTION
Using the proper blade is important for setting up the
correct cutting conditions. Blades are made differently
depending on the specific application intended for the
blade. Some simple rules can still be applied to almost
all blades.
Always remember to have at least three teeth in contact
with the work during a cut. When three teeth are in con-
tact, the blade cannot straddle the work. This prevents a
tooth that enters the cut from encountering more mater-
ial than it can remove.
"Shocking" occurs when blade teeth contact too
much material. This can strip the teeth from the
blade.
When cutting harder materials, the suggested minimum
number of teeth in contact is six because "shocking" on
harder materials has a more detrimental effect on the
blade. The optimum number of teeth in contact with the
workpiece distributes the blade forces among more
teeth to increase cutting efficiency and reduces blade
wear. The optimum range is from 6-12 teeth in contact
for soft materials, up to 12-24 teeth in contact for harder
materials.
Always have the maximum number of teeth in con-
tact with the work to prevent the gullets of the teeth
from being clogged.
When choosing a blade, the overall size of the work is
not as important as the thickness average. The thick-
ness average is the average width of the material which
the blade will contact during each cut. Figure 11
describes how the thickness average should be
6

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