Brother b831 - Clearance between Rotary Hook and Bobbin Case Opener

0 CLEARANCE BETWEEN ROTARY HOOK AND NEEDLE PLATE
Rotary hook shaft bushing upper
1.2 mm
_L
★ Rotary hook O is set to the proper height by the rotary hook shaft bushing upper so that the clearance between rotary
hook O and needle plate O is set as required (1.2 mm).
0 CLEARANCE BETWEEN ROTARY HOOK AND BOBBIN CASE OPENER
★ Adjust the clearance between rotary hook O and
bobbin case opener O to about 0.2 mm (when the
bobbin case opener O has retracted fully in the arrow
direction) by loosening screw O and moving bobbin
case opener O to the right or left.
* Afterthe adjustment, tighten screw O securely.
0.2 mm
1.
Needle to rotary hook point gap
• Rough seams, skipped stitches, thread breakage, needle
breakage
2.
Needle bar rise, height
• Rough seams, skipped stitches, thread breakage
3.
Rotary hook to needle plate gap
• Too small: improper stitch tightening
4.
Rotary hook to bobbin case opener gap ..
•Too large: loose stitches, improper stitch tightening
•Too small: shuttle body damage
»
Be sure to readjust rotary hook lubrication when the rotary hook is replaced.
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