How the Thread Break Sensor Works (and why it alarms when the thread isn't broken)

How the Thread Break Sensor Works

The thread break sensor is the round device located just above and to the left of the tension knob. It works by sensing the movement of the check spring. Take a few stitches and watch the check spring go up and down, past the sensor.

If the check spring doesn't pass by the sensor, because the thread has broken and is no longer pulling on the check spring, the thread break alarm will sound.

But My Thread Isn't Broken

Tension on the thread will affect the movement of the check spring. A very delicate, loose tension may mean the check spring doesn't come down past the sensor at all. A very tight tension might keep the check spring permanently below the sensor. Or if the check spring isn't oriented correctly, it may never pass by the sensor. Any of these situations will cause the thread break sensor to sound the alarm.

Solutions

1. Adjust the thread tension to ensure that the check spring passes by the thread break sensor with every stitch.

2. Or adjust the placement of the check spring, so it will pass by the sensor with every stitch.

3. If you're in the middle of a project and don't want to change your tension, you may turn off the alarm on your display.