Embroidery thread tension - it's a matter of balance
Imagine a tug-of-war with two teams pulling on the opposite ends of a rope If their strength & technique are exactly the same then neither team will be able to pull the rope and the knot will stay right in the centre. Now add an extra team member to one side and suddenly the balance is broken. One team will out-pull the other - the knot moves towards the stronger team.
On our embroidery machine we also have to have balance. The difference is that we don't want the knot (where the bobbin and needle threads meet) to start in the middle - we want it to start AND stay slightly to one side (the underside of the fabric).
Start by setting the bobbin thread tension Before we try to adjust the needle thread tension we must make sure that all of the bobbin tensions are set to the right level and that they are all the same.
With or without a bobbin tension gauge If you don't have a bobbin thread tension gauge like the one shown above you really should consider getting one. They take all of the guesswork out of tension setting - especially for untrained operators.
A good starting point is to set the bobbin tension so that when you hang the bobbin & bobbin case by the end of the thread and then jiggle it up and down, a little bit of thread unwinds each time. If you do have a tension gauge, this would be the equivalent of between 10 and 15 grams bobbin thread tension. Note: depending upon the make and model of machine which you use, you may need to use a higher tension setting than this - but please remember that higher tension means more friction (increased breakage) and more puckering and possible design registration problems too. To increase bobbin thread tension, use a small jewellers screw driver and turn the bobbin tension spring adjustment screw clock-wise by about one eighth of a turn - then re-check. Note: If turning the tension adjusting screw clock-wise does not seem to have much of an effect then it is possible that there may be a built up of lint or wax under the spring.
Adjusting needle tensions to suit - (one third / one third / one third) Once you have set all of the bobbin tensions to be the same then you can begin to adjust the needle thread tension accordingly. Look on the reverse side of the embroidery and check how much needle thread V's bobbin thread you can see on narrow columns. If the tension is balanced you should see: * On one side of the column 1/3 needle thread * In the middle of the column 1/3 bobbin thread * On the other side of the column 1/3 needle thread
Whilst I strongly recommend the bobbin tension gauge I am not so enthusiastic about needle tension gauges. Why? Well, it's because the amount of tension required for a balance can vary between rayon and polyester threads and from one make of thread to another. It can even be different from colour to colour in the same make of thread so it is unlikely that there will be just one tension value that will work with every needle thread.
Usually your new machine tensions will have been adjusted during testing and will be fairly close to the required level. Minor adjustments are usually all that is necessary.
TIPS: 1. Make up a test pattern of small, fill stitch rectangles with narrow borders - one rectangle for each needle on your machine and each rectangle a different colour.
2. For more accurate tension adjustment - carry out checks using narrow columns
3. Even if the tension looks good on satin stitch columns it might still be a little loose when for fill stitch areas producing an untidy looking fill which has small loops on top.
