51500A - Sewing machine Union Special - Free user manual and instructions
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| Brand | Union Special |
| Model | 51500A |
| Product Type | Industrial Sewing Machine |
| Machine Style | Overlock / Serger |
| Stitch Type | Overlock (4-thread or 5-thread) |
| Max Sewing Speed | 6500 stitches per minute |
| Number of Threads | 4 to 5 threads |
| Needle System | DC×27 or 81×1 (depending on setup) |
| Sewing Thickness | Light to medium-heavy fabrics |
| Feed System | Positive combined feed with differential feed |
| Dimensions (approx.) | 400 mm (W) x 250 mm (D) x 450 mm (H) |
| Weight (approx.) | 28 kg (without table and motor) |
| Power Supply | AC 220V 50/60Hz (also available in 110V) |
| Motor Power | 0.2 kW (clutch motor or servo motor) |
| Lubrication | Automatic oil pump with oil window |
| Safety Features | Finger guard, needle guard, protective eye cover |
| Spare Parts Availability | Needles, loopers, feed dogs, knives, tension assemblies |
| Repairability | Modular design with readily accessible internal components |
| Maintenance | Daily cleaning, periodic oiling, and stitch formation checks |
| Included Manual | Free PDF user manual (66 pages, English) |
Frequently Asked Questions - 51500A Union Special
What type of machine is the Union Special 51500A?
The Union Special 51500A is an industrial overlock sewing machine, commonly used for serging, edge finishing, and seaming knit or woven fabrics.
How do I thread the Union Special 51500A?
Threading the 51500A involves following the color-coded thread path on the machine body. Start from the spool, pass through the tension discs, take-up lever, and finally the needle and looper. Always raise the presser foot and set the needle at the highest position before threading.
What needles should I use with the 51500A?
The recommended needle system is DC×27 (also known as 81×1) in sizes 70/10 to 90/14, depending on fabric weight. Use sharp needles for wovens and ball-point needles for knits.
How do I adjust the thread tension?
Begin by setting all tension dials to the midpoint (e.g., 4). Test on a scrap fabric and adjust gradually. The needle thread tension should be strong enough to prevent loose loops, while looper tensions should be balanced to create a neat seam.
How often should I oil the 51500A?
The machine has an automatic oil pump. Check the oil window daily, and refill with high-grade sewing machine oil when it is below the minimum mark. Run the machine for a few seconds after oiling to distribute the lubricant.
What are the main stitch forms of the 51500A?
The 51500A can produce 4-thread and 5-thread overlock stitches, including a safety stitch that combines an overlock seam with a chainstitch, making it ideal for durable flat seams.
How do I replace the cutting knife?
Ensure the machine is off. Locate the lower knife and upper knife assembly. Loosen the fixing screws, remove the old knife, insert the new one, and adjust the cutting gap (approx. 0.1 mm). Tighten and test with a scrap piece.
Why are stitches skipping?
Check needle condition and ensure it is inserted correctly (flat side facing the hook). Verify needle size matches the thread. Also inspect the looper timing and tension. Improper threading is a common cause, so retread carefully.
Can I sew lightweight or stretchy fabrics?
Yes, the 51500A handles light to medium fabrics with ease. For stretchy knits, use a ball-point needle and slightly loosen the differential feed to prevent stretching or waviness.
Where can I download the free user manual?
The user manual in PDF format is available for free on the notice-facile.com website. Simply search for the Union Special 51500A and download the 66-page English manual.
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USER MANUAL 51500A Union Special
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Product information
Brand : Union Special
Model : 51500A
Category : Sewing machine