why does my sewing machine keep jamming

Why Does My Sewing Machine Keep Jamming?

Frequent jams can bring your sewing project to a frustrating halt. There are several common reasons why sewing machines jam up, but identifying and addressing the root cause will get you stitching smoothly again.

The quick answer:

  • Using incorrect thread weight, needle type, or bobbin
  • Built-up lint and debris obstructing the machine
  • Improper upper or bobbin threading leads to tangles
  • Bent, damaged, or dull sewing machine needle
  • Incorrect thread tension settings (too tight or loose)

[Bulleted list of 5-7 brief steps]

  • Rethread the machine top and bobbin carefully
  • Clean out any lint buildup with a small brush
  • Inspect needle for damage and replace if bent/burred
  • Adjust upper and bobbin tension per manual instructions
  • Ensure thread, needle, and bobbin are properly matched
  • Oil moving parts, if needed for your machine
  • Have a technician service if jamming persists

Can’t seem to resolve those stubborn stitching jams? Don’t fret – often the solution is simple once you identify the culprit. Ready to banish jams for good?

Common Sewing Machine Jamming Culprits

While sewing machine jams are incredibly frustrating, they usually stem from just a few typical causes. Let’s explore some of the most common reasons behind the dreaded jam.

Incorrect Thread, Needle, or Bobbin

Incorrect Thread, Needle, or Bobbin
Photo credit: freepik

Using the wrong type of thread, needle, or bobbin for your fabric weight and machine is a surefire recipe for jams. Always consult your manual to ensure you’re using the proper:

  • Thread weight and fiber content (all-purpose, heavyweight, etc.)
  • Needle type (universal, ballpoint, stretch, etc.) and size
  • Properly wound bobbin specified for your machine

For example, lightweight thread with a heavy needle can cause snapping and tangles, while a too-thin needle will bend and distort when forced through thick fabrics like denim or canvas.

Lint and Debris Buildup

Sewing machines are essentially miniature factories – they generate lint, dust, and stray thread snippets that can accumulate in areas like the feed dogs, bobbin case, and tension discs. This buildup can restrict movement of key components and create snags that cause threads to bunch and jam.

It’s essential to regularly clean out any lint and debris buildup with a small brush or lint roller. Check under the bobbin case, needle plate, and other areas outlined in your manual. A quick cleaning routine will keep things running smoothly.

Improper Threading

If the upper thread or bobbin thread is threaded incorrectly through any of the guides or tension discs, it can easily loop around and get caught, causing an instantaneous jam when you start sewing.

Always start by rethreading the entire machine carefully whenever you encounter jams. Double-check that the bobbin is inserted properly and that the bobbin case tension is correctly positioned. Most sewing machines have threading guides printed on the body to simplify this process.

Bent, Dull, or Damaged Needle

One often-overlooked cause of sewing jams is a bent, dull, or damaged needle. A needle in this condition can easily snag and pull on threads and fabric, causing them to bunch up and jam in the mechanism.

Get in the habit of changing needles regularly – a good rule is to swap for a new needle around every 4-6 hours of sewing. Also, inspect needles periodically and change any that are bent, dull at the tip, or buried along the shaft. A new sharp needle makes a world of difference!

Incorrect Thread Tension

For quality stitches to form, the upper and bobbin thread tensions must be properly balanced per the settings for your machine and project type. Tell-tale signs of incorrect tension include thread bunching, nesting, or skipped stitches.

Refer to your sewing machine’s manual for guidance on adjusting both the upper thread tension and bobbin case tension. Getting this tension balanced properly will go a long way to preventing jams.

Resolving Persistent Jams

If you’ve checked all the typical culprits listed above and adjusted where needed, but pesky jams persist, it may be time to have your sewing machine professionally serviced.

Components like tension discs can wear out, even with diligent cleaning and care. More complex mechanical issues could also be at play. Many manufacturers offer annual tuneup services through local dealers to restore your machine to perfect working order.


My sewing machine keeps jamming on thick fabrics like denim – what could be causing this?

Jamming on heavier weight fabrics often occurs when using a needle that is too small or thin for that fabric type. Switch to a denim or jeans needle size 14-18 and a stronger upper thread like polyester or topstitching thread. Also ensure your tension settings are adjusted properly for the thick fabric.

I am getting constant jams when sewing stretchy knit fabrics. Any tips?

Use an appropriate ballpoint or stretch needle for knits and stretchy fabrics to avoid skipped stitches and jams. You may also need to loosen the upper tension slightly. A walking or even-feed foot can help feed knits smoothly.

Why do I get jams more frequently when using the zig-zag or decorative stitches?

Zig-zag, satin, and dense decorative stitches are simply more prone to jamming due to the extra thread movements involved. Go slowly with these stitch types and keep the area clear of lint buildup. Using a higher-quality thread can also help minimize jams on complex stitches.


Don’t let frustrating sewing machine jams slow down your sewing productivity! With some detective work to identify the root cause, a minor adjustment, cleaning, or repair can get that machine running smoothly again. What are your tried-and-true tips for eliminating jams?


Main image: pexels

Priti Nandy
Priti Nandy
Articles: 249

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