Pfaff 3334 - 3. Mechanical Setup

23. Changing the Knives
Th'e knives should be sharpened from time to time, particularly when the machine Is
used constantly. To strip the knives, tilt the machine over to the left and rest it on the
-wooden peg. Open the cylinder bed cap, loosen nut M (Fig. 21) and take out screw N.
Next, remove pinion stud bracket 0 and the knife assembly.
The knife assembly can also be removed from above. To do this, loosen hexagon screw
b (Fig. 22) in the feed plate and pull the plate out of its mount. Then take out the four
needle plate screws and remove the needle plate with the attached knife assembly by
pulling it forward.
R 5952
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Fig. 21
The knives are secured to the knife carrier only by screw a (Fig. 22). Take out this
screw and strip the knives. Sharpen them with a knife grinder or exchange them for
new knives.
In replacing the knives make sure they fit in the knife carrier groove correctly. Then
tighten screw a securely. The meshing teeth of the rack and the pinion are spotted
(Fig. 21) so that the knife bar need not be readjusted after the knife assembly has been
replaced. To replace the knife assembly in the machine simply reverse the above proce
dure.
Fig. 22
24. Adjusting the Knife Motion
When you depress the left treadle after the machine has stopped, the knives swing for
ward to the operative position. During this operation the tip of the bobbin thread knife
may swing slightly beyond the right edge of the cylinder arm, but it should be flush with
this
edge when the treadle is depressed completely.
If the knife protrudes from the edge, loosen lock nut H (Fig. 17) and adjust the position
of regulating block Gi in the slot of the lifting lever.
From the library of: Superior Sewing Machine & Supply LLC