ELNA Supermatic Service Manual page 34

Lower Tension Device
How it works
The Graduated Screw adjusts the lower thread tension by
pivoting the Lower Tension Lever, thereby changing the force
applied on the Lower Tension Spring.
Turning the screw Clockwise increases the tension.
Turning the screw Counterclockwise decreases the tension.
There are detents around the perimeter of the Graduated
Screw head at ¼ increments between 0 and 3.5.
Normal tension should be set at "1" as shown.
Revisions
There were numerous changes made to the shuttle assembly including the: Upper guard ring, Shuttle beak,
Graduated screw, Spacing plate, Upper guard ring screws and spring. Please refer to the 3 revisions of the parts
catalogs to identify which configuration applies to the machine you are servicing. Changes are noted with the
machine serial number when the change was made.
The individual components on the machine you are servicing may appear to be different than those illustrated
here. However, it does not appear that any of the changes affect how the lower tension is adjusted in this
section.
Checking the normal tension
With the graduated screw set at "1," a slight tension must be felt when a fine thread (No.120) is drawn by band
between upper guard ring and lower tension skid. For this test the bobbin thread must be loose so that it does
not pull and turn the bobbin.
If no tension at all, or if too much tension of the lower thread is observed, adjust as follows:
Adjusting the normal tension
Remove the Upper Guard Ring from the shuttle.
Loosen both Shuttle Beak fastening screws about 2 turns, and
then lift the portion of the shuttle beak with the notch which
locks the Lower Tension Axle, preventing it from turning.
Turn the Lower Tension Axle to adjust the normal tension
setting. To increase the tension, turn it clockwise; to decrease
tension, turn it counterclockwise.
Tighten both shuttle beak fastening screws and confirm that
the lower tension axle is properly locked by the Shuttle Beak.
Replace upper guard ring and tighten the two screws. Make sure that the two small springs (under the heads of
the above screws) are also inserted.
Recheck the tension of lower thread as explained above. If necessary, repeat above adjustment.
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