JUKI MB-377 User Manual

1. SPECIFICATIONS
MB-373
MB-377
Other specifications are same as those of MB-373.
−1 −−1 −
1
2
3
4
5
6
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8
9
10
11
Sewing speed
Number of stitches
Amount of feed
Stitching pattern
Button size
Needle bar stroke
Needle
Automatic thread trimmer
Presser lifter
Stop-motion unit
Power supply
Max. 1,500 rpm Normal speed 1,300 rpm
8, 16, and 32 stitches
(6, 12 and 24 stitches are also possible by changing the cam.)
Crosswise feed 2.5 to 6.5 mm
Lengthwise feed 0, 2.5 to 6.5 mm
コ -shape, Z-shape, Π -shape, and X-shape
10 to 28 ø mm
48.6 mm
TQ x 7 #16 (#14 to #20)
Interlocked with the presser lifter.
Consists of a fixed knife and a moving knife.
Automatically operated (Pedal-system is also available.)
Automatically operated (equipped with speed slowing device)
200 W (1/4 HP) single- or three-phase
1
2
Stitching pattern
Needle
コ -shape, Z-shape, and X-shape
TQ x 1 #16 (In case of attachments for medium button (Z202) and
large button (Z201) TQ x 7 #16, #14 to #20)

JUKI MB-377 Specifications

General

Brand	JUKI
Model	MB-377
Category	Sewing Machine
Language	English

Summary

Standard Adjustment

Height of the needle bar

Aligns needle bar with lower bushing at lowest position.

Positioning the needle and the looper

Details needle-looper timing and clearance adjustments.

Timing the travel of the yoke slide

Adjusts crosswise and lengthwise movement timing of the yoke slide.

Positioning the cloth feed cam

Aligns cloth feed cam with pivot at stop motion.

Floating timing of the tension disc No. 2

Sets needle bar height for tension disc No. 2 floating timing.

Lift and pressure of the button clamp

Adjusts button clamp lift height and pressure.

Thread tension disc No.1

Adjusts thread tension disc No.1 float at stop motion.

Positioning the thread nipper

Sets clearance for thread nipper and nipper block.

Positioning the stitch adjusting cam

Sets clearance between cam roller and recess at stop motion.

Positioning stop motion disc and plunger

Sets clearances for stop motion disc, plunger, and lever.

Pressure of the button clamp

Sets distance from bottom of pressure adjusting nut.

Positioning the button clamp lifting link

Sets clearance between lifting link and forked rod.

Positioning needle driving pulley pressure lever

Sets clearance for needle driving pulley at stop-motion.

Positioning the thread pull-off lever

Adjusts thread pull-off lever position relative to thread guide.

Adjustment of Automatic Thread Trimmer

Thread trimmer mechanism and components

Explains components and operation of the automatic thread trimmer.

Clearance: button clamp lever and adjusting screw

Sets clearance between button clamp lever end and adjusting screw.

Adjusting moving knife position

Sets moving knife position relative to throat plate slot.

Adjusting thread separating claw height

Sets clearance between thread separating claw and looper.

Installing the button clamp lifting rod

Sequence for installing button clamp lifting rod and parts.

Adjustment of Knot-Tying Mechanism

Knot-tying mechanism and components

Describes components and working principle of the knot-tying mechanism.

Positioning the knot-tying arm stopper

Sets clearance between knot-tying arm roller and stitch adjusting cam.

Positioning the knot-tying notch

Sets knot-tying notch position with needle height reference.

Adjusting thread bind plate (MB-377)

Sets clearance between needle and thread bind plate at stop-motion.

Adjusting tension lever (MB-377)

Sets distance between tension guide and tension lever tip.

Adjusting speed slowing friction plate (MB-377)

Sets clearance between friction plate and friction wheel.

Corrective Measures for Stitching Troubles

Thread breakage

Troubleshooting causes and corrective actions for thread breakage.

Thread remaining and poor stitch tightness

Addresses issues of trailing thread or stitches lacking tightness.

Skip of stitches

Corrective measures for stitches being skipped.

Thread slippage from needle

Solutions for thread slipping, preventing stitch formation.

Excessive remaining thread

Troubleshooting excess needle or looper thread left after sewing.

Corrective Measures for Mechanical Failures

Defective stop motion

Diagnosing and fixing stop motion functionality issues.

Button clamp does not go up

Corrective measures for button clamp failing to lift.

Needle driving pulley clutch slips

Troubleshooting needle driving pulley clutch slippage.

Overheated needle driving pulley and rough start

Addressing overheating and rough start issues of the needle driving pulley.