Cord Trimmer; Theory And Operation Of The Trimming Function - AMF Reece S-101 Installation Manual

S-101
TROUBLESHOOTING

CORD TRIMMER

This part of the Digest concerns the cord trimmer units and problems peculiar to the Cord Trimming
Machine. Troubles on the basic part of this machine, where there is a similarity of parts and functions, should
be looked up in the Digest on previous pages.

Theory and Operation of the Trimming Function

When the stitching of the buttonhole is completed, the Head and Cam Case move forward to cutting
position. This forward movement is ample to cause the upper thread to break at the knot of the last stitch.
The severed end is then picked up and held by the thread pick up hook actuated by the cutting lever as
shown on Sheet 24, Figure 2. It will be noticed that during the sewing cycle the thread tension assembly
rocks to the front of the machine and retracts when the machine comes to a full stop. This action provides
the desired quantity of upper thread to start the next buttonhole.
In the meantime, as the upper thread is severed at the knot during the Head and Cam Case forward
movement to cutting position, the under thread draw off mechanism goes into action as shown on Sheet 24,
Figure 3, to draw off a supply of under thread from the source of supply and through the under thread
tension. The free under thread thus provided is then drawn through the slot in the Throat Plate by the action
of the thread hook, Sheet 25. Figure 1. This action occurs just before the under thread and cord are
severed by the trimming shears. The combined actions on the under thread, as outlined, and the extent of
these actions assure that a sufficient length of under thread extends through the slot in the Throat Plate as
shown on Sheet 25, Figure 2, for the start of the next buttonhole.
The trimming shears can operate only when the cloth holding members, commonly referred to as clamps
have risen to release the work. Therefore in order that the work shall remain firmly held in trimming position,
the Hold-Down finger shown Sheet 26. Figure 5 is utilized as an auxiliary work holding member. The Hold-
Down member is brought into action as the Head and Cam Case are moving forward to cutting position.
The trimming shears are then free to operate and no movement of the work can occur to effect the trimming
action or nullify the thread draw-off provisions as outlined above.
The trimming shears which are mounted on the clamps, are actuated by a lever on the race. The trimming
occurs as the race rotates just before the machine stops. Only the under thread and cord are trimmed by the
shears. The upper thread as had been noted above is not served by the trimming shears. After the cord has
been severed, the excess length of cord is drawn back by the weight mechanism shown Sheet 26, Figure 1,
so that only a sufficient end is left protruding through the hole in the Throat Plate to start the next operation.
The operation of the various elements may be observed in slow motion by stopping the machine at the
completion of the last stitch and then turning the left hand crank slowly until the machine reaches its normal
stopping position.
It is advisable to make sure that the machine is stitching and operating properly before making adjustments
to the trimming mechanism.
Revised 09/2004
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