Improper threading of the upper thread in a PMZ sewing machine leads to constant breaks, looping at the bottom and skipped stitches, which completely stops the work process. To eliminate these defects, it is necessary to strictly follow the thread route through all levers and compensators, ignoring which, you will not get a high-quality seam even on new fabric. Errors at the initial setting stage most often occur due to the thread passing through the eye of the spring compensator or the incorrect position of the thread guide.
Brand equipment Podolsk, including the popular models of the 2M and 3M series, requires the use of threads of a certain thickness, otherwise the tension mechanism will not be able to work correctly. If the needle is installed with the blunt side forward or is not fully inserted into the needle holder, threading loses all meaning, since loop formation is disrupted at a fundamental level. The correct passage of the thread provides uniform tension, necessary for sewing dense materials such as jeans or drape.
Preparing the workplace and checking the needle
Before you start threading, you need to make sure that the needle is working properly and that it is installed correctly in the needle holder. The needle should be inserted all the way into the needle bar, with the long notch (flat) on the needle shaft pointing to the right when looking at the machine from the front. Incorrect needle position is one of the most common reasons why the PMZ machine does not make a stitch or breaks the thread immediately after piercing the fabric.
The choice of needle number directly depends on the type of material being processed and the thickness of the threads used. For thin fabrics such as silk or cambric, needles number 70-80 are suitable, while for thick jeans or coat fabrics, numbers 100-110 should be used. The use of a blunt or curved needle is strictly prohibited, as this damages the tissue structure and leads to displacement shuttle mechanism.
⚠️ Attention: Never try to push the needle into the needle holder with excessive force; if it does not go in all the way, check whether the fastening screw or foreign object is in the way.
Make sure the presser foot is down before you start threading, as this is the position where the tension dials are open, allowing the thread to pass freely between them. If you thread the machine with the foot raised, the thread will not get between the discs and there will be no tension, causing looping at the bottom. Check the cleanliness of the area around the needle plate, removing any lint or dust that may have accumulated from previous work.
Upper thread route: step-by-step diagram
The filling process begins with installing the reel on the reel rod, which can be positioned vertically or horizontally depending on the modification of the PMZ machine. The thread should be wound counterclockwise, passing through special felt pads, if they are provided for in the design of your specimen. Next, the thread is passed through the upper thread guide, which is a metal loop or hook on the top of the body.
The next critical step is to pass the thread through the tension regulator, where it must pass between two metal discs. After the regulator, the thread must be wound behind a spring-loaded compensator (pin), which serves to remove excess thread when lowering the needle. Skipping this element results in the thread constantly breaking or forming a “beard” at the bottom.
Technical nuances of the compensator
The tension relief is a movable lever with an eye that, when the needle is lowered, moves forward, loosening the thread tension. This is necessary so that the shuttle can easily wrap the upper thread around the lower one. If the thread is not tucked into the eye of the compensator, it will be constantly tensioned and the shuttle will not be able to make a turn.
From the compensator, the thread rises up to the thread take-up - a movable lever with a hole that makes reciprocating movements. Threading into the thread take-up eye is carried out strictly from right to left (or from front to back, depending on the model), after which the thread falls down to the needle. On its way to the needle, the thread passes through the lower thread guide located directly above the needle, which ensures a perpendicular entry of the thread into the eye of the needle.
- 🧵 Place the spool on the rod and thread the thread through the upper fixed thread guide.
- 🔩 Pass the thread between the tension regulator discs with the presser foot raised (to decompress the discs).
- 🔄 Thread the thread into the eye of the spring compensator (checks), without skipping this step.
- ⬆️ Pass the thread through the eye of the thread take-up from top to bottom or from right to left.
- 👇 Pass the thread through the lower thread guide and insert it into the eye of the needle from front to back.
Threading the bobbin thread and installing the hook
The lower thread is threaded into the bobbin case, which in PMZ machines is swinging and is removed to replace the thread. Insert the wound bobbin into the cap so that the thread winds counterclockwise, and pull the end of the thread through the slot in the side wall of the cap under the spring plate. The bobbin thread tension is adjusted by a screw on the bobbin case spring plate, but the factory setting is usually optimal and does not require intervention.
After threading, the bobbin case is installed in swing shuttle, in this case, the protruding lead of the cap should fit into the groove on the shuttle body. Fixation occurs with a characteristic click when the delay tab closes the cap, preventing it from falling out during operation. If the cap is not installed correctly, the machine will make a knocking sound and the thread will not be picked up by the needle.
☑️ Checking the installation of the shuttle
To bring the lower thread up, you need to hold the end of the upper thread with your left hand, and with your right hand slowly turn the handwheel towards you, lowering and raising the needle. In the lower position, the needle will grab the bottom thread and pull it up in a loop, after which both threads are placed under the foot. The length of the free ends of the threads should be at least 10-15 centimeters so that they do not pull out of the ears when starting to sew.
Setting thread tension for different fabrics
The quality of the seam directly depends on the balance of tension of the upper and lower threads, which is adjusted depending on the thickness and structure of the fabric. In cars Podolsk The main adjustment tool is the upper thread tension adjuster nut located on the needle bar rod. When turning the nut clockwise, the tension increases, and counterclockwise, it loosens, which allows you to adapt the machine to a specific material.
The perfect seam looks the same on both sides of the fabric, with the weave knot hidden within the material. If the loops of the lower thread are visible from above, it means that the tension of the upper thread is loose or the lower thread is too tight. Conversely, if the loops of the upper thread are visible from below, it is necessary to loosen the upper tension or check whether the thread is correctly threaded into the compensator.
| Fabric type | Needle number | Tension adjustment | Stitch length |
|---|---|---|---|
| Thin (silk, chiffon) | 70-80 | Loosen (2-3 divisions) | 1.5 - 2 mm |
| Medium (cotton, linen) | 90 | Average (4-5 divisions) | 2.5 - 3 mm |
| Thick (jeans, drape) | 100-110 | Strengthen (6-7 divisions) | 3 - 4 mm |
| Knitwear (stretch) | 90 (with rounded end) | Medium/weak | 2.5 mm |
When sewing special materials such as leather or very thick coat fabrics, it may be necessary to adjust both tensions at the same time. In such cases, it is recommended to first loosen the tension of the lower thread by tightening the screw on the bobbin case, and then adjust the upper tension with the adjuster nut. Do not forget to return the settings to their original position after working with special materials, so as not to damage the seams on ordinary fabrics.
Tip: If the thread keeps breaking when sewing multiple layers, try increasing the stitch length a little and lowering the handwheel speed while using your hands to help feed the fabric.
Troubleshooting common refueling problems
One common problem is the thread jumping off the thread take-up during operation, which often occurs when starting abruptly or using synthetic threads that are too smooth. To prevent this, make sure the thread fits snugly in the thread take-up eyelet and that there are no knots or bulges that could get caught. It is also worth checking whether the thread take-up eye itself is not deformed, as burrs can cut the thread at high speed.
Looping of the thread from below (“beard”) most often indicates that the thread did not pass through the tension compensator lever or the tension regulator does not work due to dust trapped between the disks. In some cases, the reason lies in the incorrect installation of the bobbin case, when the thread did not get under the spring plate. A thorough recheck of the entire thread route from top to bottom usually allows you to quickly localize and eliminate the defect.
⚠️ Attention: If the thread breaks with a characteristic melted end, this may indicate overheating of the needle due to friction against too thick a fabric or using a needle with a dull point.
Skipping stitches can be due not only to threading, but also to a mismatch between the needle number and the thickness of the thread or fabric. A thin needle with a thick thread will create excessive friction in the eye, leading to breaks, and a thick needle on thin fabric will leave large punctures and can damage the thread. Compliance with the “fabric-needle-thread” proportions is a fundamental rule for the stable operation of any sewing machine, including vintage PMZ models.
Maintenance and lubrication of mechanisms
Regular maintenance of a PMZ sewing machine includes not only cleaning from dust, but also timely lubrication of rubbing parts with special oil. Before threading, it is recommended to drop one drop of oil into the place where the hook rotates and on the thread take-up axis, then spin the machine without thread to distribute the lubricant. Lack of lubrication leads to rapid wear of parts and makes it difficult for the machine to move, which indirectly affects the quality of the threading and seam.
Cleaning the feed dog and needle plate should be done after every long sewing session, as lint buildup interferes with the progress of the fabric and can get caught in the tension mechanism. To clean, use a soft brush or the special brush included in the accessories kit, avoiding the use of sharp objects that could scratch the chrome surfaces. The cleanliness of the mechanism is the key to ensuring that the thread will pass through all the nodes without hindrance.
The main conclusion: 90% of problems with seam quality on PMZ machines are solved by correctly threading the thread through the compensator and installing a new sharp needle of the appropriate number.
Periodically check the condition of rubber parts, such as belts (if your model has them) or shock absorbers, as their destruction can lead to rubber crumbs getting into the mechanism. Store the machine in a case or cover to prevent dust from collecting on exposed parts, especially the tension adjuster discs. Proper care extends the life of equipment, allowing it to serve for decades without major repairs.
What to do if the thread constantly gets tangled in the shuttle?
If the thread gets tangled in the hook, you must stop the machine and raise the needle to the highest position. Carefully cut off the tangled thread, being careful not to damage the needle point or the surface of the hook. Check that the bobbin case is inserted correctly (until it clicks) and that the thread passes under the spring plate. Often the cause is that the upper thread tension is too loose or the use of poor quality thread with uneven thickness.
Can I use different colors of thread for the top and bottom threading?
You can use threads of different colors, but this requires perfect tension settings. If the tension is broken, the color of the bottom thread will be visible on the face of the fabric, and the color of the top thread will be visible on the back. For decorative stitches this is an acceptable technique, but for a regular seam it is better to use the same threads to hide possible minor adjustment defects.
How often do you need to change the needle in a PMZ machine?
It is recommended to change the needle after each large project or when the first signs of dullness appear (skipped stitches, tightening on the fabric). Even if the needle is visually intact, microscopic burrs on the tip can damage the fabric. For professional work, the needle is changed every 8-10 hours of clean sewing.