Sewing a Consistent Seam Allowance

What you will learn

• Reading needle plate guides
• Keeping an even seam allowance
• Pressing seams open

Materials and tools

• Threaded machine
• Two scrap strips of woven cotton, 4 x 12 in (10 x 30 cm)
• Washi tape or masking tape
• Seam gauge
• Iron

Before you start

• Check the needle plate guide lines. They are measured from the needle. Common markings are 3/8 in, 1/2 in, 5/8 in or 10, 15 and 20 mm. Models differ, so check the manual.

1. Find the 5/8 in (15 mm) line on the needle plate. This is the usual seam allowance in sewing patterns. Check the pattern for the allowance it asks for.

2. Place the strips right sides together. Slide them under the foot with the raw edges lined up along the guide line.
3. Lower the needle by turning the handwheel toward you and lower the foot. Sew slowly. Keep the fabric edge against the guide line the whole way.
4. Use your fingertips to hold the fabric against the line, without pulling. If you drift, correct a little at a time.
5. If your plate has no clear lines, stick a strip of tape on the plate, with its edge at the required distance from the needle. Use the seam gauge to place it. Do not put tape over the feed dogs or slots.
6. At the end, secure the seam and remove the fabric.
7. Measure the seam allowance at three places with the gauge. They should all match.
8. Press the seam open by folding the layers back and flattening the allowances on each side with an iron at a setting that suits the fabric.

Tips for a neat result

• Sew a trial seam on scrap with the same fabric before starting the project.
• On a curved edge, keep your eyes on the guide, not the needle.

Common mistakes and fixes

Check your result

• Three measurements along the seam agree within 1/16 in (1.5 mm).
• The pressed seam lies flat.

Projects that use this