Tension issues?  Clean your bobbin, clean and rethread your upper thread(s) and do the I-test

The I test sounds like it should go along with your iPhone and iMac or testing your eyes,  but don’t worry, it’s completely different and has to do with your embroidery machine!

I have noticed a growing trend on Facebook – tension issue posts.  Not everyone knows what causes the tension issues or how to fix them, but tension issues can be a big problem and can ruin your embroidery.  Tension issues can “pop up” in the middle of embroidery, at the end or at the beginning of a new project – your machine can be perfectly tensioned and then the next stitch its out and you have white bobbin showing through. It can happen at any time and it can happen to you.

What are tension issues?  Tension issues have to do with either the top or bobbin thread.  If your bobbin tension is too loose, the bobbin thread will come up and show up in your work.  If your top tension is too tight, you will probably have a lot of broken or shredded threads.  What happens if your top tension is too loose?  Birds nest are a possibility, as well as loopy and messy embroidery.    The I test is to help with the top thread tension, and I would suggest that every few months, or if you change thread brands you should run an I test.

Most of the time when your bobbin is showing through to the top, it is bobbin tension.

It sounds complicated, and sometimes it can be a bit of work to figure out what is going on, especially if you have a multi needle machine!  All you need is a place to start to become a good “tension Detective”.  You need to figure out the tension issues and get your machine back into balance.   Here are a few suggestions, the first step we take is looking and analyzing the issue – loops, bobbin thread showing, threads breaking, etc. Once you understand what the issue is, you can then move on to the solution and get back to embroidery!

What is the I  test?  It’s actually really easy to do on your machine.  If you have a multi-needle machine, you will have answers for each needle regarding tension.  Newer machines actually have the I test in the built-in designs!   Look for a series of capital letter “I” in a row, and that is your eye test.  If you don’t have it built into your machine, you can use your software to stitch out a few I’s to make this work – the idea is one capital letter I for each needle and thread color.   Then all you have to do is stitch them out and get your detective boots on and analyze the results!

We just bought a new machine and fixed another one, so before we do any work on either of those machines, we do an I test on each.  Here are the results:

how to fix machine tension

Fig 1 (10 needle)

This is the back of the embroidery, so we can see the balance between the bobbin thread and the top thread.  The perfect balance is for the white bobbin thread to be through the middle and be taking up about 1/3 of the space, and each side has the top color, taking up 1/3 each side.  You don’t have to be precise, but you can see in the first image of the 10 needle I-test, we have some issues!   Needle number 1 in red looks great – a nice balance between the two, although I would still adjust the top tension a little bit because it is not quite 1/3 at the sides.  However, I don’t think you would have any issues with stitching using this tension.  If you look at the silver thread (needle 5) you can see that the bobbin thread down the middle is really small – not close enough to the 1/3 measurement that we want.  That means that the top tension is too loose, and we need to tighten that one up a bit. You can see that the other ones are just about right, and the balance of 1/3 is good for the bobbin and top thread.

If you did an I test, and each needle has too much bobbin thread showing down the middle, I would adjust the bobbin – you can clean the bobbin case and slightly adjust the bobbin tension – if it is on every needle every time, then it is bobbin.  Once you make that bobbin adjustment, then run the test again and you can start working on the top tension.

Let’s look at Figure 2, the 6 needle machine that just got it’s motor fixed.  Yep, wow, that tension is out on just about every needle!

how to adjust tension

Figure 2, 6 needle

Needle number 1 (silver) has the start of a birds nest and some loops of the top thread that completely covers up the bobbin thread.  Yes, that one needs to be fixed before we do any more stitching.  Because that one has so much thread showing, I would completely unthread that needle, right back to the thread spool, and clean the thread path with a small soft brush or possibly some canned air if it is really bad.  I would double check the tensioners, and then re-thread – and then check the pathway again.  Turns out that there was a small mistake in threading and we missed one path of the thread – and it made that big of a difference!  Without making any tension adjustments, we stitched the I on that needle again, and it was perfect!  So before messing with the tensioners, make sure that your thread path is clean, and that you have followed the path properly – I have been threading machines for 15 years, and it is pretty easy to miss one of the tiny steps that the thread takes on the multi-needle machines!

Let’s look at needle 3, brown.  Oh, that tension is a bit off too – there is not nearly enough bobbin showing on that one – we need to adjust so that we can get back to the 1/3 measurement.  When you are making tension adjustments, I would advise some baby steps!  For my 6-needle, the tensioners are all marked off in increments – even though this needle is quite off, I would not do a full turn of the tensioner, I would do maybe a ¼ turn and see how that worked first.  If it is not quite there, then I would do another ¼ turn and then stitch it again until it is perfect.  It is easier to tell which way to go (tighter or looser) when you are only working in small steps – if the next ¼ turn is too much, then all you have to do is put it back ¼ turn and you know you have it exactly where you want it.  If you were to make a full turn, then you would still have no idea where the perfect mark is, and you will take more time to figure it out.  Baby steps!

I would also like to point out that each tensioner is probably set differently.  What I mean is that you can’t just set one up perfectly (if there were numbers, say tension number 12) and do that for each needle – set each to 12 and have them all work fine – you have to do each needle separately, one at a time.   Chances are the tension settings will be similar, but each one will be different.  There is no room for shortcuts when it comes to the tension!

Tension issues can happen at any time!  Keep an eye on your work – and if you see some loose threads or the bobbin showing, you need to make some adjustments – the tension is not going to fix itself.

Keep in mind, there are some quick fixes that will work to help your tension issues – if you have a tension problem, you don’t always have to stop what you are doing and immediately do an I test.  The I test is for maintenance, to fine tune your tension.

One of the biggest issues to tension is fluff.  Fluffy stuff building up in your bobbin case or a tiny piece of fluff in your tensioner.  It really does not take much to throw your machine off tension!  And yes, it can happen any time – you could be in the middle of an embroidery project and see bobbin thread coming up.  Yucch!  Immediately stop your machine and have a quick look at your bobbin.  If you have a multi needle machine, I would carefully take a thick piece of paper or business card corner, and slide it under the tension part of the bobbin to clean out that fluff!  Then pop it back into your machine and keep stitching.  If you have a single needle machine stop your machine, take the hoop off, take out the bobbin and grab that tiny brush and remove all of the fluff that is in there.  Yucch again – I bet you will find more than you thought you would!   Once you have removed all of that fluff, your bobbin tension should be back on track.

how to clean your bobbin case

There are many more things that can affect thread tension – changing brands of thread, humidity and sometimes temperature can change the “elasticity” of your thread and throw your machine off tension balance.  With regular cleaning and checking your thread path, as well and keeping your machine well oiled and keeping your bobbin case clean, you can keep your machine running in tip-top tension and have beautiful, sharp and clear embroidery each time.


Until next time,

Happy Digitizing,



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