Thread ‘Caterpillars’ in Embroidery Machines

Posted by Stephen Taylor on

Thread ‘Caterpillars’ in Embroidery Machines

              NO, NOT THIS                                  THIS    
I often get asked about those annoying little lumps that occur on your embroidery thread, which we call ‘Caterpillar. This is not a technical term but we think it describes what these little lumps of shredded thread look like, a little fuzzy caterpillar clinging to the thread.

First of all, it helps to know what is causing them, where they actually happen and what you can do to help to reduce them to a minimum. Although they are not something that you can ever get rid of altogether, even professional machine embroiderers, with banks of multi-head machines, accept them as a fact of life.

The first thing to realise is that, technically, they are not caused by the machine itself, although they are a symptom of how the sewing machine actually functions. It is therefore important to know a little of how a machine makes a stitch and, more importantly, where the problem actually occurs.

The sewing machine works by picking up the thread using a pointed, rotating hook and looping it around bobbin containing a second thread. It then pulls the loop of thread back from the bobbin using the take-up lever to form the stitch. The thread, therefore, passes through the needle, backwards and forwards on and off of the hook several times before it is incorporated to a stitch, anything up to 15 times if the stitch is small. You can see this if you mark the thread where it comes through the fabric and the run the machine very slowly (turn the wheel towards you by hand or repeatedly press the needle up/down button) and count how many times you see the mark fly up and down before it becomes part of a stitch.

The point where the ‘caterpillar’ is actually caused is where the thread runs through the needle needle and  occurs through abrasion of the thread, causing fibres to be rubbed off, making the thread thinner and pushing the fibres along until it eventually breaks. The ‘caterpillar’ is then found somewhere in the head of the machine in the region of the take-up and tension units.

Now to the causes, of which there are several possible and it is when more than one happen at once that the problem occurs. They are as follows:-

A worn needle eye causing abrasion of the thread. Always use good quality needles and change them regularly. A good quality needle (Organ, Gros-Beckert, Schmetz) will last about 10 to 12 hours of stitching, although this can be reduced when sewing certain materials which cause more wear to the needle.

The wrong type or size of needle needle. Embroidery needles have a large eye to be kinder to the soft nature of embroidery thread. A larger needle is needed when using thick, dense or hard fabrics and/or stabilisers to give a larger hole for the thread to pass through.

A very soft thread which is more prone to shredding. Unfortunately some of the nicest looking embroidery threads are also the most fragile and are therefore more prone to ‘caterpillaring’.
Reducing the the machine’s speed and possibly using a “metallic’ needle (which has an even larger eye) can usually help here.

A bad reel of thread. Unfortunately, it can happen, even with the best quality threads, it is possible to get an occasional faulty reel. Fortunately this is not so common.

Fabric.Certain fabrics are more abrasive than normal and can cause problems by wearing away the thread, Again a larger needle, plus slowing the machine down, will often help.

Lastly, the most irritating cause, Atmospheric conditions! Yes thats right thread, because it is spun, thread tends to react to temperature and humidity, which cause variations in the twist. This can make it more fragile and prone to abrasion. This is why some really large embroidery factories, particular in the far east, are fitted with environmental control systems, like the ones used in museums, so that the atmosphere does not vary.

If you are getting problems with a reel of thread and a fabric/stabiliser combination that you have not had trouble with before then this is almost certainly caused by atmospherics. Unfortunately the only thing we can do is, once again, to slow the machine down.

There is one other possible cause of thread shredding, although this one is not so  common. When it does happen it is almost invariably with a older machine. It happens because a part of the thread path has become worn, either through use or incorrect threading, and the thread is finding it’s way into the resultant groove. Damage to the needle plate, where a needle, or multiple needles, have been broken can also cause shredding. This can also cause shredding of the bobbin thread but this is much less common. In these cases a repair is likely to be needed.

So, these infuriating little ‘creatures’ are, unfortunately, a fact of life for us machine machine embroiderers (Incidentally they can also happen in ordinary sewing on a machine but, as ordinary sewing threads are generally harder, it is less prevalent).

Hopefully, now you understand what’s causing them, you can reduce them to a minimum.


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