How to Replace Embroidery Machine Tension Knobs

In this video, we show how to replace the tension knobs on both the pre-tensioner and the main tensioning device of an embroidery machine. At the top of the machine head and on the thread rack are the pre-tensioning devices, while the main tensioners are located in the middle of the embroidery head. On a pre-tensioner, the springs are the parts that most commonly wear out. On the main tensioning device, the internal spring can fail, and the felt pads may also need to be replaced as they wear down.

We begin with the pre-tensioner by loosening the knob until it comes free. We then carefully remove the spring and the holder on the front of the spring, which frees the tension washers. At that point, we clean the washers thoroughly and make sure there is no lint or buildup inside, including on the back washer. We then reinstall the washer assembly, replace the spring with the new one, put the holder back in place, and reinstall the pre-tensioner knob. If we noted how many threads were showing before removal, we can use that as a good starting point when setting the tension again. If not, we can verify the setting with an H-test.

To change the main tensioning device, we remove the screw in the front, then take off the holder, the spring inside, and the back piece. This exposes the felt pads, with two in the back and one in the front. We inspect the felt pads to make sure they are in good condition and replace them if needed. We then reassemble the unit by putting the bottom back in place, followed by the spring, the retainer, and the adjustment knob. As with the pre-tensioner, counting the visible threads on the shaft before disassembly gives us the simplest way to return to a good starting point.

After reassembly, we re-thread the upper thread sensor and then thread the main tensioner. By following these steps, we successfully replace both the pre-tensioner and the main tension knob assemblies and prepare the machine for final tension adjustment.