The following practices and procedures help
to ensure safe and smooth operation of the sewing
machine:
1. The balance wheel must always turn toward
the operator.
2. Do not run the machine with the presser
foot resting on the feed dog without material
being under the presser foot.
3. Do not run the machine when both bobbin
case and needle are threaded unless there is
material under the presser foot.
4. Do not try to help the machine by pulling
the material. You may bend or break the needle.
If properly adjusted, the machine feeds the work
without assistance.
5. The slide over the bobbin case should
be kept closed when the machine is in op-
eration.
6. Keep your head away from the thread take-
up lever and needle bar at the top of the sewing
machine face.
7. When running the machine, do not take
your eyes away from the needle and presser foot.
8. Keep your fingers from under the needle.
9. When running the machine, keep your
fingers away from the belt and pulley areas.
10. Never attempt threading the needle when
the machine is turned on.
Lubrication
To ensure easy operation and to prevent
unnecessary wear of the moving parts, all sewing
machines need oiling. When a machine is in
constant use, it should be oiled twice a day. Anew
machine should be oiled more frequently when
in constant use. Use only one drop of oil at each
oiling point. A 10W mineral oil is recommended.
Oiling points for the 31-15 machine are shown
in figures 9-3, 9-4, and 9-5. Oil should be applied
regularly to the shuttle bearing in the shuttle race.
Occasionally, remove the faceplate and apply oil
to the bearings and points that are uncovered.
Timing the 31-15
There are two distinct timing operations for
the 31-15 machine. One operation times the needle
with the shuttle; the other timing operation times
the feed dog with the needle. Both the needle with
the shuttle and the feed dog with the needle must
239.263
Figure 9-3.—Oiling points at the front of the machine.
9-4
