51400K - Sewing machine Union Special - Free user manual and instructions
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| Type | Industrial Sewing Machine |
| Brand | Union Special |
| Model | 51400K |
| Stitch Type | Lockstitch |
| Number of Needles | 1 |
| Max Sewing Speed | 4,500 stitches per minute |
| Max Stitch Length | 5 mm |
| Needle System | 135x17 (DBx1) |
| Presser Foot Lift | Manual knee lift or hand lever |
| Lubrication | Automatic oiling system |
| Power Supply | 220-240 V, 50/60 Hz |
| Motor Power | 550 W (clutch motor) |
| Dimensions (L x W x H) | 55 x 25 x 40 cm (machine head only) |
| Net Weight | 35 kg (machine head only) |
| Table Dimensions | 120 x 60 x 80 cm |
| Turning Radius | 180 degrees |
| Thread Take-up | Rotary hook |
| Bobbin Winder | Built-in, manual |
| Presser Foot Pressure | Adjustable |
| Feed Mechanism | Compound feed (needle, presser foot, and drop feed) |
Frequently Asked Questions - 51400K Union Special
How do I thread the Union Special 51400K?
Refer to the threading diagram on the machine. Start by placing the spool on the pin, then guide the thread through the tension discs, take-up lever, and needle eye. Ensure the thread passes through all thread guides.
What type of needle should I use?
Use 135x17 (DBx1) needles. The size depends on the fabric thickness; typical sizes range from 16 to 23.
How do I adjust thread tension?
Turn the tension dial for the needle thread. The bobbin tension is adjusted via the screw on the bobbin case. Balanced tension produces even stitches.
Why is my machine skipping stitches?
Skipped stitches may be due to a bent needle, incorrect needle size, or improper threading. Check the needle for damage and ensure the thread is seated in the tension discs.
How often should I oil the machine?
Oil daily if used heavily. Use high-quality sewing machine oil. Apply to all moving parts indicated in the manual, especially the hook area.
What is the maximum fabric thickness?
The 51400K can sew multiple layers of denim or canvas up to 5 mm thickness.
How do I replace the bobbin?
Lift the needle to its highest position, open the hook cover, and remove the bobbin case. Insert a fully wound bobbin ensuring the thread pulls clockwise.
What is the best lubricant for the hook assembly?
Use non-detergent sewing machine oil. Avoid using WD-40 or household oils as they can damage the machine.
How do I change the needle?
Loosen the set screw with a screwdriver, remove the old needle, and insert a new one with the flat side facing away from you. Tighten securely.
Where can I find replacement parts?
Replacement parts are available from Union Special dealers or online industrial sewing parts retailers. Use the model number 51400K for accurate parts.
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