Thread Tension & Troubleshooting | Sewing Machine Basics
Why does the thread tear when stitching?
Thread breaks are one of the most common sewing machine problems. There are many reasons why thread breaks, most of which even a novice seamstress can fix. Let’s take a closer look at each case and how to solve a particular problem.
Most thread breaks are caused by incorrect upper thread tension. Some modern computer machines are already equipped with electronic tension adjustment, but regular domestic machines require manual adjustment.
Be sure to check the thread tension when switching to a tighter fabric, after installing a new needle, or when using different thread densities!
Properly tensioned upper thread gives beautiful stitching from the front and back. The intertwining of upper and lower threads should be recessed into the fabric and be inconspicuous. It is easier to adjust such a stitch if you put the lower thread in the bobbin of a contrasting color.
An additional sign of proper adjustment is not too tight a thread from under the lowered leg, if you just pull it with your hand.
Sometimes a loose thread tension can also be the cause of a thread break. Stitching then creates excessive loops in the hook compartment, and the thread becomes tangled and then breaks.
Adjust the hook thread tension as a last resort, e.g. when sewing very thin or thick fabrics, or very tight or thin threads. The adjusting screw should be turned only half a turn at the most, otherwise it can come out completely with vibration while sewing.
A correctly tensioned bobbin thread should come out of the cap when suddenly yanking on it while the cap is hanging loosely by 3 to 5 cm. If the cap continues to unwind, the thread is too loose, if the thread does not come out at all, it is too tight.
Upper thread breakage
Move the hook stroke housing to the left until the gap between the needle and thread guide plate is 1 mm at the right zigzag prick. Perform the following steps to make the adjustment:
b) in the hook device to remove the bobbin case, locking ring and hook;
c) on the thread guide plate to make the right cut at an angle of 90° (the factory produces at an acute angle) ;
Fig. 8. Thread-guiding plate on the locking ring (a machine “Chaika”-142M cl.):
|a. before repair;||b. after repair (the acute angle on the right edge is beveled at 90°);|
|1. right working edge|
Fig. 9. Mechanism of the housing stroke hook, shaft and crank (machine “Podolsk”-142 cl.):
|1. Shaft pusher hook;||8. sector gear;||15. cone lock nut;|
|2. limiting ring of tappet shaft;||9. left bushing of the shaft of the shuttle;||16. shaft crank;|
|3. hook stroke housing;||10. platform flush;||17. connecting rod cone;|
|4. trunnion cover fastening bolts;||11. cam of the rack lift;||18. crank bolt;|
|5. housing trunnion cover;||12. shuttle shaft;||19. locking screw of the left sleeve;|
|6. Body trunnion;||13. right bushing shaft shuttle;||20. conical driven gear;|
|7. ring locking latch;||14. right sleeve locking screw;||21. upper screw fixing pinion|
Sewing Mistakes 101: Thread Breaking
e) loosen the bolts 4 fixing trunnion 6 housing stroke hook 3. Loosen the screws 14, 19 mounting both bushes 9, 13 horizontal shaft 12 sector gear 8;
f) Shift right shaft sleeve 13 to the left for 5 mm. Loosen both screws fixing cam 11 of rack lift. It is on the shaft of the sector gear;
Fig. 10. a. compensation spring of the upper thread tension regulator (Veritas machine 8018-2 кl.); b. setting bevel pinions engagement (machines “Podolsk”-142 kl., “Chayka”-134 cl.);
|1. upper screw;||4. extreme toothed sector gear;|
|2. first prong;||5. bottom screw;|
|3. second prong;||6. shuttle pusher shaft|
Fig. 11. Thread guide plate of the hook stroke housing (machine 2M cl. PMZ):
|1. annealing zone;||3. holes, kerfed at 2 mm to the side of the work area|
|2. working area;|
Fig12. Right-handed shuttle with a shoulder (machine “Seagull”-142M cl. etc.):
|a. shuttle with a notch 2 (marriage);||b. normal hook;|
|2. ledge formed by a deflected cutter on the left side;|
|3. hook belt|
Fig.13. Earnings on the shuttle (machine “Singer”, “Seagull”-2M cl. PMZ):
|1. hook spout;||2. burr on the vertical plane of the hook (at the entrance of the thread)|
In sewing machines, 822 cl. PMZ, “Veritas-8014/35”, etc., Where there is a rotary hook (as in industrial machines), breakage may be due to:
a) a sharp burr from the threaded hole inside the shuttle;
In this case, the following should be done:
a) saw off on the housing of the hook at its entrance (for 2M PMZ. left, “Seagull”. right) flats; depth of 1 mm. the beginning and end, the length of flats. 8-10 mm;
Poor thread quality
Sometimes it is not the technique that creates an even stitch. Checking why the sewing machine tears the thread, it is worth examining the consumables themselves. A mismatch between the bobbin number and the fabric or needle often leads to these results. Sewing machine tears upper thread when jammed in eyelet at high speed. Solve the problem by simply replacing it with thinner thread that matches the fabric and needle. If a thread breaks when sewing, you should check its quality. Sometimes materials that have been in stock for a long time are sold. In addition, cheap thread is often of extremely poor quality simply because the manufacturer has used low quality raw materials.
When looking for a reason why a sewing machine rips thread, you should pay attention to the needle. It is in direct contact with the material and the mechanism can break and lose their sharpness. Servicing sewing machine, it is worth carefully inspect all of its components. Needles should be replaced periodically, especially if they have been pressurized, there is deformation. When running a sewing machine, especially when the upper thread is often torn, this is one of the first elements to check.
How to fix upper thread breakage in the sewing machine
You may be wondering what to do if the machine rips thread from the top or bottom. We will tell you a little about the ways to fix the problem.
The most common causes of thread breaks in a sewing machine are the wrong materials. In this case, you just need to inspect the threads and needles for defects, and replace them with new ones.
The first thing to do is to check the thread tension. Properly tensioned upper and lower threads should intertwine internally, not on the surface of the fabric. Try to adjust the tension with the upper thread. The lower thread should only be touched as a last resort.
If the tension is OK, check if the needle goes into the hole in the plate correctly. To do this, turn the thumb wheel slowly and use a magnifying glass to check that the needle does not touch the hole wall.
Check that the spring is correctly positioned. If most of it is facing the wrong way, then turn it over. If the problem is that the slot is too tight, unscrew the nut.
You should also check that the voltage regulator is correctly assembled. For this, you’ll need the instructions for your model of machine. Pay attention not only to whether the elements are in the right order, but also whether they are turned the wrong way round.
In most cases the problem of thread breaks can be solved by yourself. However, if after checking all the parts you do not find a problem, then contact your adjuster.
Causes of skipped stitches
If the machine started skipping stitches, start looking for the cause by following the principle “from simple to complex”.
The first thing to check is this:
- Thread tension. This parameter can be affected by errors in threading, as well as the soiling of the device. Check and adjust this parameter in the way indicated in the manual.
- Needle type. Perhaps the domestic sewing machine was installed a needle of the industrial type, with a round bulb, or another that does not match your machine. The wrong needle will not interact properly with the shuttle, resulting in skips. Be sure to check the marking of the needle, it must coincide with that specified in the instructions for the machine.
- The needle may be bent or blunt. Replace the needle with a new one and check the stitching, the problem of skipped stitches may be solved. Many craftsmen recommend changing the needle after sewing 2-3 products, and the changed sound when piercing the fabric. a definite signal of the need for such replacement.
- Needle and fabric combination. Sewing with knitwear, denim or leather requires the use of special needles. Attempting to sew complex materials with a universal needle can cause poor stitching.
- Needle and thread combination. Thick thread in a thin needle when sewing can lead to loops in the material output and therefore to skips in the stitching.
- Poor quality threads can also cause a problem. Warped thread forms knots, causes loops to form incorrectly and the hook nose can’t pick them up. When sewing, use quality threads of uniform thickness and without excessive torsion, matching their size to the needle and fabric being used.
- Damaged needle plate. A “broken” hole in the plate draws the fabric inside, which does not allow the thread to move freely and form the necessary loop. In this case, only a complete replacement of the needle plate can help.
If you have checked all of these causes and the machine is still not sewing correctly, check the clearance between the eyelet and hook spout. It will be easier to do with a magnifying glass.
- Set the “straight stitch” operation.
- Remove the needle plate and presser foot.
- Lower the needle bar as much as possible. Raise the needle 1.8 to 2 mm. At this point, the nose of the hook should be above the ear by 1.1-2 mm, and the distance between them (gap) should be from 0.15 to 0.25 mm. The maximum allowable value is 0.3 mm, a larger value will prevent the spout from catching the loop of upper thread.
If you are convinced of the wrong values of the gap, you will need mechanical adjustments to the equipment. We recommend trusting such work to a professional, especially if the machine is under warranty service.
The following causes will help you find out why the sewing machine is skipping stitches when sewing. Check the needle, thread, and tension settings before working, and remember to periodically clean the machine of debris.
Why is the upper thread ripped?
The reasons why this happens can be as many as possible:
- There is a problem with the thread tension regulator. You can try loosening the upper thread to the maximum possible value to begin with. It is then recommended that the regulator be slowly tightened to the proper tension. Thread breakage can occur with too little or too much thread tension;
- Wrong thread thickness for the needle. If the thread is too thick, it will jam in the eyelet at high speed and tear. In addition, tearing can also be caused by poor quality thread itself;
- The threading was not done correctly;
- The size of the needle is not appropriate for the type of fabric;
- The needle was incorrectly installed: it should be set so that the groove “looks” in the direction of the thread guide.
Often, replacing a dull or broken needle at the end of the needle can also help.
To understand why a torn thread is interfering with your sewing, in most cases you can do it yourself. Repair by rollers on youtube is also easy to do with their own hands, especially if it is uncomplicated. But sometimes it is better to call a master. Contacting him will be needed in the case if:
Expert advice. In the sewing machine “Tula” of the old type and in other similar units quite often go out of order details. If this is a problem, you can find replacements through private ads. Similar difficulties are experienced by masters, who have a sewing machine “Seagull” at their disposal. Avoid unnecessary costs will help to carefully care for the technique, regular lubrication of its mechanisms.
What to do? General recommendations
Each case requires an individual solution. But there are general recommendations so that the thread does not tear while sewing:
- Be sure to check and adjust the tension when you install a new needle, change to thread or material of a different thickness.
- Use quality needles, threads, and other supplies.
- Install the parts according to the instructions.
- Choose threads and needles for the thickness and type of fabric.
- Do not disassemble the machine yourself if you are not sure that you can assemble it correctly.
- Keep an eye on the condition and cleanliness of the mechanism and external elements.
If fixing any of these problems has not helped you, and the machine is still tearing the upper or lower threads, it may be in the system itself adjustment. We recommend calling a handyman to fix the problem.