1. Introduction
This instruction manual provides essential information for the proper installation, function, and maintenance of the Cutex Juki Lower Knife, part number 700-00399. This genuine replacement part is designed for specific Juki MO-6800 series industrial overlock sewing machines. Adhering to these instructions will help ensure optimal performance and longevity of your sewing machine's cutting mechanism.
Image 1: The Cutex Juki Lower Knife, part number 700-00399. This image shows the elongated, flat metal blade with a sharpened edge, designed for precision cutting in industrial overlock machines.
2. Safety Information
WARNING: Always prioritize safety when working with sewing machines and sharp components.
- Disconnect Power: Before attempting any installation, maintenance, or adjustment, always turn off and unplug your sewing machine from the power source.
- Handle with Care: The lower knife has a sharp edge. Handle it carefully to prevent cuts or injuries. Use appropriate protective gloves if necessary.
- Proper Tools: Use only the recommended tools for installation and removal to avoid damaging the knife or machine components.
- Read Machine Manual: Refer to your specific Juki MO-6800 series overlock machine's instruction manual for detailed safety procedures and component access.
- Keep Away from Children: Store replacement parts and tools out of reach of children.
3. Installation (Setup)
Replacing the lower knife requires careful attention. If you are unsure about any step, consult a qualified sewing machine technician or your machine's official service manual.
- Prepare the Machine: Ensure the sewing machine is turned off and unplugged. Lift the presser foot and open the front cover to access the cutting mechanism.
- Remove Old Knife: Locate the existing lower knife. It is typically secured by one or two screws. Carefully loosen and remove these screws. Gently extract the old knife, being mindful of its sharp edge.
- Clean Area: Use a brush or compressed air to clean any lint, dust, or debris from the knife mounting area.
- Install New Knife: Position the new Cutex Juki Lower Knife (700-00399) into its slot. Ensure it is seated correctly and aligned with the upper knife.
- Secure Knife: Insert and gently tighten the retaining screws. Do not overtighten, as this can strip the threads or damage the knife.
- Adjust and Test: Refer to your Juki MO-6800 series machine manual for specific instructions on adjusting the knife clearance and timing between the upper and lower knives. Once adjusted, manually turn the handwheel a few times to ensure smooth operation and proper cutting action before powering on the machine.
- Close Covers: Once satisfied with the installation and adjustment, close all machine covers.
4. Function and Operation
The lower knife works in conjunction with the upper knife to trim the fabric edge precisely before the overlock stitches are formed. A sharp and properly installed lower knife is crucial for clean, consistent seams and preventing fabric fraying. While the knife itself does not have operational controls, its correct installation directly impacts the machine's cutting performance during sewing operations.
5. Maintenance
Regular maintenance of your lower knife will extend its lifespan and ensure optimal cutting performance.
- Cleaning: Periodically, with the machine unplugged, use a small brush to remove lint and fabric fibers that accumulate around the knife area.
- Inspection: Regularly inspect the knife edge for nicks, dullness, or damage. A dull knife can lead to frayed edges, skipped stitches, or fabric jamming.
- Replacement: Knives are wear-and-tear parts. Replace the lower knife when it becomes dull or damaged, even after cleaning. The frequency of replacement depends on usage and fabric types.
6. Troubleshooting Common Issues
If you experience issues related to the cutting mechanism after installing the new lower knife, consider the following:
| Issue | Possible Cause | Solution |
|---|---|---|
| Fabric not cutting cleanly / Frayed edges |
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| Knife jamming or hitting other parts |
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| Excessive noise from cutting area |
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For persistent issues, consult your Juki MO-6800 series overlock machine's service manual or contact a professional technician.
7. Specifications
- Part Number: 700-00399
- Alternate Part Number: KR35, 70000229
- Type: Lower Knife
- Compatibility: Juki MO-6800 Series Industrial Overlock Machines, including MO-6804, MO-6814, MO-6816
- Brand: Cutex (Genuine Juki Parts)
- Item Weight: Approximately 3 ounces (85 grams)
8. Warranty and Support
Specific warranty information for this replacement part is not provided in this manual. Please refer to the original purchase documentation or contact the seller, Cutex Sewing Supplies, for details regarding warranty coverage and support.
For technical assistance or further inquiries, you may contact the manufacturer or an authorized Juki service center.
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