51400BJ - Sewing machine Union Special - Free user manual and instructions
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| Product Type | Industrial single-needle lockstitch sewing machine |
| Brand | Union Special |
| Model | 51400BJ |
| Stitch Type | Lockstitch (301) |
| Maximum Sewing Speed | 4,500 stitches per minute |
| Stitch Length | 0 to 5 mm (adjustable) |
| Needle System | DB x 1 (#9 to #21) |
| Material Range | Light to medium weight fabrics |
| Lubrication | Automatic oiling system |
| Power Supply | 220-240V AC, 50/60 Hz, 0.4 kW (motor included) |
| Dimensions (L x W x H) | 60 cm x 30 cm x 40 cm (approx.) |
| Weight | 32 kg (approx.) |
| Table Included | Yes, industrial stand with table top |
| Safety Features | Hand guard, presser foot safety switch |
| Maintenance | Daily cleaning and oiling; periodic belt and needle replacement |
| Spare Parts Availability | Widely available through Union Special distributors |
| Repairability | Modular design; serviced by authorized technicians |
Frequently Asked Questions - 51400BJ Union Special
How do I thread the Union Special 51400BJ?
Raise the presser foot and turn the handwheel to raise the needle to its highest position. Place the thread spool on the pin, then follow the threading path: from the spool through the top tension disc, then down through the check spring, up through the take-up lever, down to the needle bar thread guide, and finally through the needle eye from front to back.
What needle size should I use for light fabrics?
For light fabrics such as chiffon or silk, use a fine needle like DB x 1 #9 or #11. Always match the needle size to the thread weight and fabric thickness to avoid skipped stitches or fabric damage.
How do I adjust the thread tension?
Turn the tension dial on the front of the machine. Turn clockwise to increase tension (for tighter stitches) or counterclockwise to decrease tension. The correct tension produces balanced stitches with no loops on either side.
Why is my machine skipping stitches?
Skipped stitches can be caused by a bent or dull needle, incorrect needle size, improper threading, or incorrect timing. First, replace the needle and rethread. If the problem persists, check the needle-to-hook timing or consult a technician.
How often should I oil the machine?
For optimal performance, oil the machine daily before use. Apply a few drops of sewing machine oil to the specified oiling points indicated in the manual, especially the hook assembly, needle bar, and feed mechanism.
What type of bobbin does this machine use?
The 51400BJ uses a Class M industrial bobbin (size 15x10mm). Ensure the bobbin is wound evenly and inserted with the thread unwinding in the correct direction (clockwise for most models).
How do I change the needle?
Turn off the machine and raise the needle bar to its highest position. Loosen the needle clamp screw with a screwdriver, remove the old needle, insert the new needle with the flat side facing the back (or as indicated), and tighten the screw firmly.
What is the maximum stitch length I can set?
The stitch length can be adjusted from 0 to 5 mm using the stitch length dial. For basting or gathering, use longer stitches (4-5 mm); for fine seams, use shorter stitches (1-2 mm).
How do I clean the feed dogs?
Remove the needle plate by unscrewing the two retaining screws. Use a soft brush or compressed air to remove lint and thread debris from the feed dogs and surrounding area. Reinstall the needle plate before sewing.
Where can I find replacement parts for this model?
Replacement parts are available from Union Special authorized dealers or online industrial sewing machine parts retailers. When ordering, specify the model 51400BJ and the part number from your manual.
User questions about 51400BJ Union Special
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USER MANUAL 51400BJ Union Special
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Product information
Brand : Union Special
Model : 51400BJ
Category : Sewing machine