Thread Trimming Device - Duerkopp Adler 171 Service Manual

2.14 Thread trimming device

Turn off main switch!
- Danger of injury -
During the trimming process the looper thread
behind the looper and the rear thread of the needle
thread loop must be caught by the point 7 of the
movable knife. See sketch.
1. Removing the knife
– Unscrew the screws 2 and remove the movable
knife 4.
– Then unscrew the screws 1 and remove the
whole thread trimmer assembly.
2. Manual trimming test
– Initially, fasten the movable knife 4 by
tightening the screws 2 slightly.
The screws 2 should be approx. located at the
centre of the elongated hole of the knife.
– Align the point 7 of the movable knife with
respect to the notch 6 of the stationary knife 5.
Tighten the screws 2 securely.
– Make a trimming test with thread.
If the thread is not trimmed properly, the edges
must be checked or new sharp knives are to be
installed.
– Set the movable knife in cutting position by
slightly turning in the pressure screw 3.
The smooth motion of the knife must be
assured.
– If necessary, align the movable knife in cutting
position with respect to the stationary knife.
3. Thread clamping sheet
The thread clamping sheet 10 should slightly
clamp the thread end to assure a secure seam
beginning.
If the clamping sheet holds the thread too
tightly, seam pucker may occur at the seam
beginning.
4. Mounting and end positions of the thread
trimmer
– Unscrew the screws 2 and initially remove the
movable knife.
– Position the thread trimmer such that the knife
holder 13 fits over the ball lever 16.
Tighten the screws 1.
7
– Screw the piston rod 12 into the block 11 until it
is flush with the face of the block.
– If the piston rod is moved into its right end
position, the edge 13 of the knife holder and
edge 14 of the plate should be flush with each
other.
Adjust the end position of the cylinder 9
accordingly (hexagon spanner 2.5 mm) using
the self-locking set screw 8.
– As a pre-adjustment fasten the movable knife
with the screws 2 such that
a) the point 7 points to notch 6 and
b) the cutting edges of the knives overlap
approx. 1 mm.
– During sewing make a trimming test with the
shortest and longest stitch length.
– If necessary, slightly correct the position of the
point 7 so that the threads are caught securely.
5. Thread puller for the looper and needle
thread
During thread trimming the thread tensions are
opened and the thread pullers 18 for the looper
and needle thread are activated. The pulled
tension-free thread is needed for secure stitch
formation at the next seam beginning.
Just the amount of thread needed should be
pulled, as this determines the length of the
thread end at the seam beginning.
– The thread puller 18 is stepped.
By adjusting the stopper 17, more or less
thread can be pulled.
5 6
17