Control the Variables with free Tension Checklist PDF
This is everyone’s favourite part of the Hello, Machine workshop because I detail exactly why it might LOOK like you have a tension issue, but it’s probably not!
Download the Tension Checklist to keep by your sewing station so you can keep sewing with fewer frustrating birds nests!
What’s the cuplrit to this birds nest? Which one of these needles is the correct size and type to sew this heavyweight linen? Or did I forget to put my presser foot down?
First, here are the mechanics around how tension discs work in your sewing machine. There are a few different tension discs on your machine, but the one that controls the needle thread either is inside your machine (maybe you have a little piece of metal popping out the top) or outside your machine (Fig. 1).
The one outside your machine is easiest to understand so I’ll be using that as a visual example to explain how these parts work. The purpose of the tension disc is to exert a precise amount of resistance on your needle thread so that, combined with the tension of the bobbin thread, it creates a symmetrical stitch on your fabric wherein both the needle and the bobbin thread meet in the middle of the fabric and neither shows on the opposite side. (Fig. 2, green fabric) When you change the amount of tension by either rotating the dial or pressing the button on your machine you are changing the amount of resistance on the thread as it is pulled through the machine. A higher number exerts more friction resulting in a tighter, more stretched thread; a lower number exerts less friction allowing the thread to pass more easily through the machine. A tension dial on a mechanical (vs. computerized) machine often has a set range that is considered normal for the machine, often 3-4-5 or 4-5-6. You may see these numbers in boxes or with dashes between them (Fig. 3) as an indication that these are your “normal” tension settings.
No adjustments can be made to the tension while the discs are closed, the spring simply cannot accept a different tension setting once it’s compressed. To make an adjustment to your tension, open the discs by lifting your presser foot so your adjustments are actually made. The discs can only exert pressure on thread if the thread is between them. The thread can only be placed properly between the discs if they are open when the machine is threaded or if you force in the thread by flossing it through (kinda like flossing your teeth, really push it in there!). The best way to explain this is to have you thread your machine with your presser foot up. While gentle pulling on the needle thread, lower the presser foot. You should feel an abrupt change to the flow of the needle thread as the discs engage and create resistance on the thread. The video shows the tension disk spring engaging and closing which causes the thread to abruptly slow. (Video 1) If you don’t feel a change in the resistance either a) your thread isn’t in the tension disc; b) your tension disc is at a low number (0-2); or c) your discs aren’t working correctly.
Things that may require you to change your tension:
changing type or thickness of thread
zigzag on a single layer of fabric
intentional gathering (moving tension up to 9 to create gathers)
The other two tension discs on your machine both affect the bobbin tension. The first one is likely at the top of your machine and it’s where your thread tucks into before turning around and winding around your bobbin, (Fig 4) This tension disc is important in making sure that your bobbin thread is wound evenly both up and down and around the center of the bobbin. Wind at a slow-medium rate to avoid over-stretching your thread as its wound. If your thread is overstretching during winding it will look like puckers in your fabric as the thread returns to its natural unstretched state, which might make you want to loosen the tension on your bobbin casing, but that would actually make your bobbin tension too loose during any other sewing. Then you might compensate by tightening your top tension. All of this can be avoided by winding the bobbin with the proper amount of tension and a slow speed.
The second bobbin tension disc is in the bobbin casing. Instead of a dial, it’s a screw that can be tightened or loosened to adjust the spring in the casing that dictates how much tension is put on the bobbin thread as it’s released into the the sewing machine. (Fig. 5) Making sure you thread your bobbin properly is essential. (Fig. 6) Drop-in or top loading bobbins also have these same mechanisms in the front of the machine.
Now that you know how the discs work, let’s talk about what might be causing those sewing issues!
Needles
Needle size and type
Using a dull or burred needle
Threading
Forgot to put your presser foot down
Incorrect threading path - missing a thread guide
Threading with the presser foot down
Threading the bobbin incorrectly
Stitches
Too long/short
Wrong type selected
Fabric
Thin/thick
Woven/Knit
Others:
Clean out the throat plate
Clean out the bobbin area
Nicked throat plate
