manual for singer sewing machine model 640

The Singer Sewing Machine Model 640 is a versatile mechanical sewing machine featuring multiple stitch patterns, adjustable stitch length and width, built-in buttonholer, free arm capability, drop feed for darning and embroidery, built-in needle threader, top drop-in bobbin system, and reverse stitching. Powered by 120V AC, this machine is ideal for home sewing projects with easy-to-use controls and durable construction. Below are key sections for safety, features, setup, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Mechanical sewing machine with built-in stitches, free arm, drop feed, built-in needle threader, top drop-in bobbin system, and accessory storage.

Installation & Setup

Unpack and inspect contents. Place on stable sewing table or surface.

1. Remove all packaging materials and protective covers.
2. Place machine on flat, stable surface at comfortable working height.
3. Connect foot control pedal to machine and plug into power outlet.
4. Install needle: Loosen needle clamp screw, insert needle with flat side to back, tighten screw.
5. Wind bobbin: Place thread on spool pin, guide thread through bobbin winding tension disk.
6. Insert bobbin: Place bobbin in bobbin case with thread running counterclockwise.

WARNING! Keep fingers away from needle area during operation. Always unplug when not in use.

First-Time Operation

Power on machine; follow basic threading procedure.

1. Thread upper thread: Follow numbered threading guide on machine.
2. Pull up bobbin thread: Hold upper thread, turn handwheel toward you to bring up bobbin thread.
3. Select stitch: Turn stitch selection dial to desired pattern.
4. Adjust stitch length and width as needed for your project.
5. Test sew on scrap fabric to ensure proper tension and stitch formation.

CAUTION! Always start with needle in highest position. Keep work area well-lit.

Specifications

• Machine Type: Mechanical Sewing Machine
• Stitches: 10 built-in stitches
• Stitch Length: 0-4mm adjustable
• Stitch Width: 0-5mm adjustable
• Buttonhole: One-step automatic
• Bobbin System: Top drop-in
• Needle System: HAx1
• Max Sewing Speed: 750 stitches per minute
• Power Source: 120V AC, 60Hz
• Dimensions: Standard sewing machine size with free arm

Controls and Settings

Main controls located on front and side of machine. Stitch Selection Dial: Choose from 10 built-in stitches. Stitch Length Dial: Adjust from 0-4mm. Stitch Width Dial: Adjust from 0-5mm.

Additional Controls: Reverse Stitch Button, Bobbin Winder, Handwheel, Foot Control Pedal, Power Switch with Light.

Thread Tension: Adjust upper thread tension dial (usually 4-5 for normal sewing). Presser Foot Pressure: Adjustable for different fabric types. Feed Dogs: Can be lowered for free-motion sewing.

Stitch Selection Guide

Available stitches: Straight Stitch, Zigzag Stitch, Multiple Zigzag, Blind Hem Stitch, Elastic Stitch, Shell Stitch, Overcast Stitch, Decorative Stitches.

1. Straight Stitch: Basic sewing, length 2.0-2.5mm for most fabrics.
2. Zigzag Stitch: For finishing edges, appliqué, stretch fabrics.
3. Blind Hem: Nearly invisible hems on garments.
4. Buttonhole: One-step automatic for consistent buttonholes.
5. Decorative Stitches: For embellishment and creative projects.

Tip: Always test stitch on scrap fabric before sewing your project.

Maintenance & Cleaning

Regular maintenance ensures optimal performance and longevity.

1. Clean lint and dust from bobbin area after each project.
2. Oil machine according to lubrication points diagram in manual.
3. Replace needle regularly (after 8-10 hours of sewing).
4. Clean feed dogs with small brush.
5. Check belt tension periodically.

CAUTION! Always unplug machine before cleaning or maintenance.

Accessories

Standard accessories included: All-purpose foot, Zipper foot, Buttonhole foot, Button sewing foot, Darning/Embroidery foot, Seam ripper/Lint brush, Screwdriver, Spool pin felt, Needles, Bobbins, Foot control, Power cord.

Safety Information

Always follow safety guidelines to prevent injury and machine damage.

• Keep fingers away from moving needle
• Unplug machine when not in use
• Do not operate with damaged cord
• Keep hair and loose clothing away from moving parts
• Use proper needle for fabric type
• Do not sew over pins

WARNING! Never leave machine unattended when plugged in.

Regulatory Information

UL Listed: Complies with UL safety standards. FCC Part 15: Class B digital device. Copyright © Singer Manufacturing Company. For support, visit www.singer.com or contact 1-800-4-SINGER. Made for household use.

Troubleshooting

Service: 1-800-4-SINGER; www.singer.com