26
(17) Bobbin thread tension
How to adjust
Disassembly
Location of components to be adjusted
Adjustment drawing
Level the
inner hook.
0.127 to 0.147 N (14 g
±
1 g)
A tension gauge is necessary to measure the bobbin thread tension.
Type of thread : SHAPPESPAN #60
Amount of thread to be wound round a bobbin : 40 to 50%
Remove the inner hook. Place the gauge as shown in the adjustment drawing and measure the
tension at a constant speed.
Throat plate
1) Adjust the longitudial position of
1
so that the
belt tension is 3 to 4 mm with 0.98 N (100g)
load, and tighten screw
2
.
Note) When performing this adjustment,
confirm the needle-to-hook timing.
(18) Timing belt
How to adjust
Disassembly
Location of components to be adjusted
Adjustment drawing
Free arm bottom cover and belt cover
Draw the thread
out from this
plane through a
narrow clearance
made on it, and
m e a s u r e t h e
bobbin thread
tension.
0.98 N (100 g)
3 to 4 mm
2
1