How to Adjust a Blind Stitch Sewing Machine?

Blind stitch sewing machines require careful calibration to produce nearly invisible hemming. The settings must be balanced to allow the needle to catch just a few threads on the fabric edge. Follow these tips to optimize your blind stitch machine.

Ⅰ.Check Needle Suitability

The needle impacts stitch formation. Use fine sharps in sizes 70/10 to 80/12 so the needle hole is narrow. Avoid thick specialty needles that create too large a perforation. Insert the needle correctly and ensure scarf is turned towards the fold edge.

Ⅱ.Set Optimal Thread Tension

Thread tension affects stitching and seam appearance. Set tension low, around 2-3, so stitches don't pucker. Always thread with the presser foot up. For knits and fine fabric, further reduce tension. Make sure threads are seated fully between tension discs.

Ⅲ. Establish Proper Presser Foot Pressure

Too much pressure flattens the fabric edge, while too little prevents smooth feeding. Set pressure between 2-3 for lightweight fabric, 3-4 for medium, and 4-5 for heavy material. The hem should roll under the foot without compression or billowing.

Ⅳ. Adjust Stitch Width Carefully

For nearly invisible results, use a narrow zigzag width of 2.0-2.5mm. This allows the needle to swing across the fold catching just a thread or two. For lightweight sheers, decrease to 1.5mm. For heavy fabrics, increase to 3mm max to avoid visible stitching.

Ⅴ. Regulate Stitch Length Precisely

With blind stitching, length should be 1.5mm or less. This produces short stitches that don't extend conspicuously into the main fabric. For firm wovens, utilize 1-1.2mm length. For elastic knits and stretchy material, keep length under 1mm.

Ⅵ. Ensure Proper Foot Alignment

Align the metal guide on the foot snugly along the folded edge. The needle should swing over just in front of the metal guide to catch the hem allowance. Loosen the guide screw to adjust alignment as required by fabric thickness.

Ⅶ. Modify Seam Width Accordingly

For single fold hems, align inner edge of foot guide to raw edge. For double folds, line up outer edge to fold. Adjust fold width so needle just pierces edge. Unfold and realign periodically to verify seam is only catching the allowance.

Ⅷ.Check Fabric Feed Tension

Fabric should glide smoothly under the foot at an even pace without stretching or rippling. Increase feed dog pressure for sheer slippery material to avoid uneven blind stitching. Decrease pressure for bulky fabrics.

Ⅸ. Clean Stitch Plate Groove

Fluff and lint can build up in the grooved plate, preventing the fabric edge from turning consistently. Regularly clean the groove with a brush and blow air to maintain easy hem rolling.

Ⅹ. Replace Needles and Foot Plates

Replace needles every 2-4 hours of use for optimal perforation. Install new foot plates when the groove wears out or develops sharp burrs that can pierce fabric. Use manufacturer recommended parts.

With practice and adjustments, you can master your blind stitch sewing machine to create flawless seams. Always test settings on scrap fabric first. The correct calibration results in a clean professional hem that is nearly invisible.

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