janome overlocker manual 644d

The Janome Overlocker 644D is a professional-grade 4-thread overlock sewing machine designed for creating finished seams, decorative edges, and professional-quality finishes on various fabrics. It features differential feed for stretch fabrics, rolled hem capability, easy threading system, adjustable stitch length and width, built-in rolled hem foot, and free arm capability for circular sewing. Below are key sections for safety, features, setup, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation & Setup 3. First-Time Operation 4. Specifications 5. Controls and Settings 6. Threading Instructions 7. Stitch Types & Applications 9. Care & Maintenance 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: 4-thread overlock capability, Differential feed system, Built-in rolled hem, Free arm design, Easy threading system, Adjustable stitch controls.

Feature	Description
Differential Feed	Prevents stretching or puckering on various fabrics
Rolled Hem	Creates narrow rolled edges for delicate fabrics
4-Thread Overlock	Professional finish for seams and edges
Free Arm	Easy access for circular sewing like sleeves and cuffs
Stitch Length Control	Adjustable from 1mm to 4mm
Stitch Width Control	Adjustable up to 7mm
Built-in Thread Cutter	Convenient thread trimming
Tension Dials	Individual controls for upper and lower loopers
Presser Feet	Includes standard and rolled hem feet
LED Light	Illuminates work area

Installation & Setup

Unpack and inspect contents. Place on stable sewing surface.

Remove packaging materials and protective covers
Install presser foot: Align foot with presser bar and secure
Connect power: Plug into appropriate electrical outlet
Oil machine: Apply recommended oil to designated points
Install needles: Use Janome standard needles, size 11/80 or 14/90

WARNING! Keep fingers away from moving parts during operation. Always unplug when not in use.

First-Time Operation

Power on machine; follow threading guide.

Thread machine: Follow color-coded threading path for upper and lower loopers
Set tensions: Start with recommended settings for fabric type
Test stitches: Use scrap fabric to adjust settings
Adjust differential feed: Set according to fabric stretch requirements
Practice basic seams: Begin with straight seams on woven fabric

CAUTION! Always use proper needle for fabric type. Test stitches on scrap fabric first.

Specifications

Stitch Types: 4-thread overlock, 3-thread overlock, rolled hem
Stitch Length: 1mm to 4mm adjustable
Stitch Width: Up to 7mm maximum
Differential Feed: 0.7 to 2.0 ratio
Speed: Up to 1300 stitches per minute
Needles: Janome standard needles, twin needle capability
Thread: Standard overlock thread cones
Power Source: 110V AC, 60Hz
Weight: Approximately 15.4 lbs (7 kg)

Controls and Settings

Access controls via front panel and side dials.

Front Panel: Power switch, Stitch length dial, Stitch width dial, Differential feed dial, Tension dials (4 total).

Stitch Length: 1mm (short) to 4mm (long). Stitch Width: Narrow to wide (up to 7mm). Differential Feed: 0.7 (gather) to 2.0 (stretch). Tension Settings: Upper looper, Lower looper, Right needle, Left needle. Rolled Hem: Engage rolled hem lever for narrow hemming.

Threading Instructions

Follow color-coded threading path for proper operation.

Raise presser foot and needles to highest position
Follow numbered threading sequence: Upper looper (blue), Lower looper (green), Right needle (red), Left needle (yellow)
Ensure threads are properly seated in tension discs
Pull threads under presser foot toward rear
Test thread chain before sewing

Tip: Always thread with presser foot raised to ensure proper tension disc engagement.

Stitch Types & Applications

Supports multiple stitch types for various fabric applications.

4-Thread Overlock: Strong seam finish for medium to heavy fabrics
3-Thread Overlock: Lightweight finish for delicate fabrics
Rolled Hem: Narrow rolled edge for sheers and delicate fabrics
Flatlocking: Decorative seam for stretch fabrics
Differential Feed: Adjust for stretch fabrics or to prevent puckering

WARNING! Always match stitch type to fabric weight and stretch characteristics.

Care & Maintenance

Unplug before cleaning. Regular maintenance ensures optimal performance.

Daily: Brush out lint from loopers and feed dogs
Weekly: Oil designated points with sewing machine oil
Monthly: Check needle plate for burrs, replace if necessary
As needed: Replace needles after 8 hours of sewing
Storage: Cover machine when not in use

CAUTION! Use only recommended sewing machine oil. Do not use household oils.

Regulatory Information

UL Listed: Complies with safety standards for household sewing machines. Copyright © 2025 Janome; trademarks of Janome Sewing Machine Co., Ltd. For support, visit www.janome.com or contact authorized Janome service centers.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Thread breaking	Incorrect threading/tension	Re-thread following color codes; adjust tension settings
Uneven stitches	Differential feed setting	Adjust differential feed for fabric type; check thread tension
Fabric puckering	Tension too tight	Loosen tension dials; adjust differential feed to 0.7-0.8
Machine jams	Lint buildup/thread tangle	Clean lint from loopers; remove tangled threads carefully
Needle breaking	Wrong needle/bent needle	Replace with correct needle type; ensure proper installation

Service: Contact authorized Janome service center for technical issues.

Support: www.janome.com or local authorized dealers