Necchi Supernova Instructions Manual page 6

FOREWORD
This service manual shall be used together with the instruction
book for the SUPERNOVA Sewing Machine and with the parts
catalogue for this machine.
The maintenance of the SUPERNOVA Sewing Machine requires
no special skill or knowledge. All that is needed is a certain
mechanical aptitude and the availability of the necessary tools.
This manual is intended only for those mechanics that make
routine repairs and replace single defective parts. Major repairs
should not be carried out by persons of limited experience.
Therefore, if major repairs are required, it is suggested that the
complete head be returned to the distributor, after prior
authorization has been received from that distributor.
The SUPERNOVA Sewing Machine, like practically all sewing ma-
chines designed for household use, works on the principle of the
Lockstitch. This type of stitch is obtained by interlocking the
upper and lower thread inside the fabric, while the needle, going
down to its lowest position, penetrates the fabric and rises again
to its highest position. The two threads of the seam are thus
tightly interlocked at every stitch, adhere closely to the fabric
and hold the plies of the fabric firmly together. If either of the two
threads breaks, or if the threads are cut off after the sewing
operation is completed, the seam will not unravel, but only two
or three stitches may get loose and open up. The illustrations
Figures " a " to " d " indicate the formation of a single lockstitch
and the interlocking of both threads in the fabric.
All machines consist of two major portions, the arm and the bed.
Arm and bed are firmly held together by means of screws and
pins. In the horizontal portion of the arm is inserted the arm
shaft (upper
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Copyright -2004