Rotary Hook To Needle Plate Gap; Rotary Hook To Bobbin Case Opener Gap - Brother b831 Service Manual

• ROTARY HOOK TO NEEDLE PLATE GAP
1
Approx. 1.3 mm
0.6~0.9 mm /
SB Standard models
★
The rotary hook O to needle plate O gapshould be0.6 to0.9 mm. Loosen screwO and adjust thevertical rotary hook
O position to adjust the gap.
SB Thread cutter models
★
The rotary hook O to needle plate O gap is set to 1.3 mm with a spacer O-
★
When replacing therotary hook, loosen screw O- and remove therotary hook O- being careful not tolose thespacer O
* Sometimes two spacers O are required. Both should be inserted under the rotary hook.
(U ROTARY HOOK TO BOBBIN CASE OPENER GAP
2.
0.2 mm
The rotaryhookO to bobbincase opener O gap should
be 0.2 mm when the bobbin case opener is pulled all
the way in the direction ofthe arrow. Loosen screwO
and move the bobbin case opener O right or left to
adjust.
Needle to rotary hook point gap •Improper adjustment may result in improper right and left
needle stitching, skipped stitches, thread breakage,
broken needles.
Needle bar rise, height "Improper adjustment may result in improper right and left
needle stitching, skipped stitches, thread breakage.
3. Rotary hook to needle plate gap
• Excessive gap: Shuttle body may not be properly
positioned near the needle plate.
• Insufficient gap: Improper stitch tightness
• Excessive gap: Loose stitches, improper stitch tighten
ing
• Insufficient gap: Damage to shuttle body
4. Rotary hook to bobbin case opener gap
Be sure to readjust rotary hook lubrication after replacing the rotary hook.