SunStar KM-640BL-7 User Manual (English)

Questions and Answers:

G
Gina SantanaAug 1, 2025
What to do if the thread breaks on my SunStar Sewing Machine?
- A
  Anna HuntAug 1, 2025
  If the thread breaks, consider these possible causes and solutions: * The threading may be wrong, so thread the needle correctly. * The needle might be bent or have a broken tip, so change the needle. * The needle could be inserted in the wrong position, so insert it correctly. * Upper or lower thread tension may be too tight, so reduce the tension. * The upper thread may be loose, so adjust the take-up lever spring.
W
Wayne Nguyen Jr.Aug 5, 2025
What to do if my SunStar KM-640BL-7 has poor thread adjustment?
- R
  ramireztanyaAug 5, 2025
  If you're experiencing poor thread adjustment, it could be due to: * Bad upper and lower thread tensions, so adjust them. * Inadequate thread take up spring tension, so adjust it. * An inadequate gap between the opener and hook, so adjust the gap.
J
Jeremy ColonAug 10, 2025
How to fix too short thread length after trimming on SunStar KM-640BL-7?
- G
  gregory19Aug 10, 2025
  If the thread length is too short after trimming, consider these solutions: * Adjust the trimming timing if it's wrong. * Adjust the thread release stroke if the opening on the thread tension control plate is too small. * Adjust the tension of the auxiliary thread tension control assembly if it's too strong. * Adjust the thread take up stroke if it's too large. * Increase the volume adjustment if the volume is adjusted to too low.
W
Walter BergerAug 16, 2025
Why does the SunStar KM-640BL-7 needle break?
- K
  Kyle PotterAug 16, 2025
  The needle may break due to several reasons: * The needle is inserted in the wrong position, so reinsert it correctly. * The needle is bent, so you should change it. * The timing of the feed dog is bad, so you should adjust it. * The timing of the needle and hook is bad, so you should adjust them.
T
Tracy PetersenAug 21, 2025
What to do if the SunStar Sewing Machine has trimming miss?
- J
  Jonathan ThomasAug 21, 2025
  If the sewing machine experiences trimming misses, consider the following: * The height and distance between the movable knife and the hook do not match, so readjust the movable knife setting position. * The tension and contact of movable and fixed knives are bad, so correct the tension adjustment and surface contact of movable and fixed knives. * The needle is not inserted correctly, so insert the needle correctly. * There is scratch and abrasion of movable and fixed knives, so replace movable knife or fixed knife. * The timing of trimming cam is wrong, so adjust the timing of trimming cam. * Thread release stroke is too small, so readjust the thread release stroke.

SunStar KM-640BL-7 Specifications

General

Brand	SunStar
Model	KM-640BL-7
Category	Sewing Machine
Language	English

Summary

Safety Rules for Machines

Machine Mobilization Safety

Guidelines for safely moving the sewing machine.

Machine Installation Precautions

Essential conditions and warnings for proper machine installation.

Troubleshooting Safety Guidelines

Procedures and warnings before and during machine troubleshooting.

Safe Machine Operation Practices

Rules and cautions to follow during sewing machine operation.

Identification of Safety Devices

Details on safety features designed to protect the user.

Caution Mark Placement and Meaning

Explains the location and significance of caution labels on the machine.

Understanding Cautionary Statements

Clarifies the specific warnings associated with caution labels.

Machine Specifications

Sewing Machine Model Details

Technical specifications for the KM-640BL and KM-640BL-7 sewing machines.

Servo Motor Specifications

Details on VOLT, WATT, and HERTZ for various servo motor models.

470 Motor Specifications

Technical data for the 470 motor, including PHASE, HERTZ, and VOLT.

470 Motor Controller Details

Specifications for the PC470 motor controller, including MODEL and SUB CLASS.

Clutch Motor Specifications

Technical data for various clutch motor models: VOLT, WATT, HERTZ.

Optional Automation Devices

Overview of optional devices like knee lifter, counter, sensors, and pedals.

Installation Procedures

Machine Head Installation

Step-by-step guide for mounting the sewing machine head onto the table.

Power Switch Box Installation

Instructions for attaching the power switch box to the machine table.

Machine Lubrication Guide

Procedures for filling and maintaining the machine's oil system.

Belt Tension Adjustment

How to properly adjust the belt tension after motor installation.

Program Unit Installation

Steps for installing the program unit for automatic trimming functionality.

Belt Cover Installation

Guide for fitting the belt cover to the machine body and table.

Synchronizer Installation

Instructions for installing the synchronizer on the servo motor.

Machine Stop Position Check

Verifying the correct needle stop position after automatic trimming setup.

Reverse Button Operation

How to use the reverse button for sewing and needle positioning.

Synchronizer Adjustment

Procedures for adjusting the synchronizer for both in-built and external motors.

Machine Adjustment Procedures

Needle Insertion and Placement

Correctly inserting and positioning the sewing needle.

Needle Bar Height Adjustment

Adjusting the needle bar to its lowest position for alignment.

Needle and Hook Timing

Aligning the needle and hook for optimal sewing performance.

Thread Take-up Spring Lubrication

Adjusting oil flow to the thread take-up spring part.

Hook Lubrication Adjustment

Confirming and adjusting the oil amount for the hook mechanism.

Lower Thread Winding and Tension

Guide to winding thread onto the bobbin and adjusting lower thread tension.

Bobbin Case and Lower Tension

Inserting the bobbin case and adjusting the lower thread tension.

Upper Thread Routing

Step-by-step process for threading the upper thread through the machine.

Upper Thread Tension Adjustment

Adjusting both the main upper thread tension and take-up tension.

Presser Foot Pressure Adjustment

Adjusting the pressure for both upper and auxiliary presser feet.

Stitch Length Adjustment

Setting the desired stitch width using the control dial.

Feed Dog Height and Inclination

Adjusting the feed dog's vertical position and angle.

Presser Foot Height Synchronization

Adjusting auxiliary and upper feed presser feet for same or different heights.

Auxiliary Presser Foot Feeding Amount

Adjusting the feeding amount of the auxiliary presser foot.

Feed Cam Timing Adjustment

Adjusting the feed cam to determine feed dog and needle timing.

Thread Trimmer Adjustment

Comprehensive guide to adjusting the thread trimmer mechanism.

Thread Trimmer Blade Pressure

Adjusting the tension and contact of the fixed and movable blades.

Movable Knife Replacement

Procedure for safely replacing the movable knife.

Fixed Blade Replacement

Steps for exchanging the fixed blade of the thread trimmer.

Thread Release Adjustment

Setting the correct opening amount for the thread tension controller dish.

Upper Thread Remaining Amount

Adjusting the amount of upper thread left after trimming.

Troubleshooting Guide

Sewing Machine Troubleshooting Table

A detailed table listing symptoms, causes, and corrective actions for common issues.

Technical Drawings

KM-640BL Table Drawing

Detailed technical diagram showing dimensions for the KM-640BL model.

KM-640BL-7 Table Drawing

Detailed technical diagram showing dimensions for the KM-640BL-7 model.

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