Why do stitches look bad? Can you fix wavy seams? What part controls the thread pull? Bad stitches, wavy seams, and loops happen because the thread tension is off. Tension is how tight the sewing machine holds the thread as you sew. Your Singer machine has parts that control this pull on the upper thread and the lower thread. Adjusting these parts makes your stitches look neat and strong. This guide shows you how to make your stitches perfect by adjusting the tension on your Singer sewing machine. You will learn about upper thread tension, lower thread tension, and how to find balanced thread tension. This helps fix stitch quality problems and thread nesting issues.
Fathoming What Tension Does
Sewing machine tension makes the top thread and the bottom thread lock together. They meet inside the fabric. Think of it like two hands holding each other. If one hand pulls too hard, the knot is pulled to one side. Sewing machine tension works the same way.
Good tension means the top thread and the bottom thread pull evenly. They meet exactly between the two layers of fabric you are sewing. This makes a strong, flat stitch on both the top and bottom of your fabric.
If the tension is wrong, the stitches look messy. They can be too loose or too tight. They might loop on one side of the fabric. This causes stitch quality problems.
Recognizing Stitch Problems
Bad tension causes problems you can see in your stitches. It is important to know what these problems look like. This tells you which tension needs fixing.
Stitch Quality Problems To Watch For
- Loops on top of the fabric: The lower thread is too loose. Or the upper thread is too tight. The top thread pulls the bottom thread up.
- Loops on the bottom of the fabric: The upper thread is too loose. Or the lower thread is too tight. The bottom thread pulls the top thread down.
- Stitches that look flat and tight: Both threads are too tight. The fabric might pucker or wrinkle.
- Stitches that pull out easily: Both threads are too loose. The seam is not strong.
- Wavy seams on knit fabric: Tension is too tight. It stretches the fabric as you sew.
Thread Nesting Issues Beneath the Fabric
This is a very common problem. It looks like a big mess of tangled thread on the bottom side of your fabric. This usually happens when the upper thread has no tension or is threaded wrong. The machine keeps feeding top thread, but it is not pulled tight. This extra thread gets jammed in the bobbin area. It creates nasty thread nesting issues.
Knowing these signs helps you fix the right part of your sewing machine tension system.
Grasping the Two Main Tensions
A sewing machine has two main places where you control thread tension.
- Upper thread tension
- Lower thread tension
You need both of these to work together. This gives you balanced thread tension.
Upper Thread Tension Control
The upper thread comes from the spool on top of your machine. It goes through guides, then through the tension discs. These discs squeeze the thread. This squeezing creates the tension. The thread then goes through more guides and the needle.
You control this squeezing with a dial or buttons on your machine. This is the sewing machine tension dial. Numbers on the dial show how much pressure is put on the thread. A higher number means more tension (tighter). A lower number means less tension (looser).
Lower Thread Tension Control
The lower thread comes from the bobbin. The bobbin sits in a bobbin case or a bobbin holder under the needle plate. The thread comes out of the bobbin case through a small slit. A spring presses on the thread in this slit. This pressing creates the bobbin case tension.
This tension needs to be just right. It must pull the upper thread down to the middle of the fabric. It also must let the upper thread pull the lower thread up a little bit.
Finding the Tension Controls
Knowing where the controls are on your Singer machine is key.
The Sewing Machine Tension Dial
Most Singer machines have a sewing machine tension dial on the front or side. It is a round knob with numbers. The numbers usually go from 0 or 1 up to 9 or 10.
- Higher numbers (like 7, 8, 9) mean the upper thread is pulled tighter.
- Lower numbers (like 1, 2, 3) mean the upper thread is looser.
- A middle number (like 4, 5, 6) is often used for a start point.
Some newer electronic Singer machines might have buttons to change the tension number shown on a screen. The idea is the same: a number tells you the setting.
The Bobbin Case
The bobbin sits differently depending on your Singer model.
- Front-loading bobbin: The bobbin case is a small metal or plastic holder. It goes into a metal shuttle under the machine. You need to open a door on the front of the machine.
- Top-loading bobbin (drop-in): The bobbin sits directly in a space under a clear plastic cover on the needle plate. It might sit in a built-in holder that acts like a case.
Both types have a way to create lower thread tension. On front-loading types, the tension is on the bobbin case itself. On top-loading types, the tension is in the area where the bobbin sits.
Adjusting Bobbin Tension
This is often called adjusting bobbin case tension. On a front-loading bobbin case, you will see a very small screw. This screw adjusts the spring pressure on the thread coming out. Tightening the screw makes the tension higher. Loosening it makes it lower.
On most top-loading Singer machines, you cannot adjust the bobbin tension easily. The tension is set at the factory. This makes adjusting bobbin tension unnecessary for most users. You usually only adjust the upper tension on these models. This is why many people start by only changing the upper tension dial.
Important: Do not change the bobbin case screw unless you are sure this is the problem. A tiny turn makes a big difference. Mark the screw’s first position with a pen before you start. This helps you return it to where it was.
Adjusting Upper Thread Tension
This is the most common tension you will adjust. It is the first thing to try for most stitch quality problems.
Steps for Adjusting Upper Tension
- Thread the Machine Correctly: This is vital! If the machine is not threaded right, tension will be wrong no matter the dial setting. Make sure the presser foot is UP when you thread. This opens the tension discs. If the foot is down, the discs are closed, and you cannot seat the thread correctly. Follow your Singer sewing machine manual for threading steps.
- Put in the Bobbin: Make sure the bobbin is wound evenly. Put it in the bobbin case or holder. Check that the thread is in the tension spring of the bobbin case/holder. Pull the bobbin thread. It should have a gentle pull, not be too tight or too loose.
- Use Scrap Fabric: Always test on a scrap piece of the same fabric you will sew. Use the same number of layers. Use the same thread you plan to use.
- Set the Dial: Start with the tension dial at a middle number. Often this is 4, 5, or 6. Sew a test line.
- Check the Stitch: Look at the stitch on both the top and bottom of the fabric.
- Perfect Stitch: The stitches look the same on top and bottom. The threads meet inside the fabric layers. They look like small, neat dashes.
- Loops on the bottom: Upper tension is too loose. The upper thread is not being pulled tight enough. It gets pulled under by the bobbin thread.
- Loops on the top: Upper tension is too tight. The upper thread is pulling the bobbin thread up to the top.
- Adjust the Dial:
- If you have loops on the bottom (upper tension too loose), turn the dial to a higher number. Try moving it up by 1 number at a time.
- If you have loops on the top (upper tension too tight), turn the dial to a lower number. Try moving it down by 1 number at a time.
- Test Again: Sew another line on your scrap fabric after each adjustment.
- Repeat: Keep adjusting the dial and testing until the stitches look balanced on both sides.
Remember, small changes on the dial make a difference. Do not jump from 4 to 9 right away. Move one number at a time.
Adjusting Lower Thread Tension (Bobbin Case)
You usually only need to adjust the bobbin case tension if:
- You have tried everything with the upper tension dial.
- Your Singer uses a metal bobbin case (often found in older or front-loading models).
- The bobbin thread is clearly too loose or too tight when you pull it out of the case outside the machine.
Steps for Adjusting Bobbin Case Tension
This needs care and a very small screwdriver.
- Remove the Bobbin Case: Take the bobbin case out of the machine. Take the bobbin out of the case.
- Find the Screw: Look for the very small screw on the side of the bobbin case. It is usually on the flat spring where the thread comes out. There might be two screws; you want the one that holds the flat tension spring. Your Singer sewing machine manual can help you find it.
- Mark the Spot: Use a fine pen or marker to draw a line on the screw head and the bobbin case next to it. This shows you the original position. This is very helpful if you need to go back.
- Make Small Turns:
- To make bobbin tension tighter: Turn the screw a tiny bit to the right (clockwise). Think of a clock face – move it like a few minutes past the hour.
- To make bobbin tension looser: Turn the screw a tiny bit to the left (counter-clockwise). Again, just a tiny turn.
- The “Drop Test”: This helps check bobbin case tension outside the machine.
- Put the bobbin back in the case. Pull about 4-6 inches of thread out. Hold the thread tail with the bobbin case hanging down.
- Jerk your hand gently up and down.
- If tension is good: The thread should feed out 1 or 2 inches with each gentle jerk. The bobbin case should hang steady, then drop slightly.
- If tension is too loose: The thread will feed out easily, and the bobbin case will drop a lot with a small jerk or just holding it.
- If tension is too tight: The thread will not feed out at all, or it will take strong jerks to get any thread out.
- Put Case Back and Test: Put the bobbin case back in the machine. Re-thread the upper thread correctly (presser foot UP!). Sew on scrap fabric.
- Check Stitches: See if the stitch quality problems are better. If the loops on the bottom are gone or reduced after making the bobbin tension tighter, you are on the right track. If you had loops on top and loosened the bobbin tension, see if they are gone.
- Repeat: Adjust the tiny screw in very small steps, test, and check until your stitches look good. Be patient.
Adjusting bobbin tension is tricky because the screw is so small. It is best to avoid this unless you are quite sure it is needed. For many Singer machines with drop-in bobbins, you cannot adjust this screw easily, or at all.
Achieving Balanced Thread Tension
The goal is always balanced thread tension. This means the top and bottom threads lock right in the middle of the fabric layers.
How to Check for Balanced Tension
- Sew a few lines on your scrap fabric.
- Look closely at the stitches on the top.
- Look closely at the stitches on the bottom.
- Pick up the fabric and gently pull the seam apart.
- Perfect Balanced Tension: The stitch looks the same on both sides. When you pull the seam, the thread loops (where top and bottom meet) should show slightly between the two layers of fabric. They look like tiny interlocked knots right in the middle.
- Upper Tension Too Loose: When you pull the seam, the bobbin thread will show more on the top side. The lock loops are on the bottom surface.
- Upper Tension Too Tight: When you pull the seam, the upper thread will show more on the bottom side. The lock loops are on the top surface.
Once you know how to check this, you can adjust the upper tension dial (mostly) or bobbin tension (sometimes) until those lock loops sit right in the middle.
Troubleshooting Sewing Machine Tension
What if you adjust tension, but the stitches still look bad? Sometimes the tension system is not the main problem. Other things can cause stitch quality problems and thread nesting issues.
Other Causes for Bad Stitches
- Wrong Threading: Is the upper thread missing a guide? Did you thread with the presser foot down? Is the bobbin thread in its tension spring? Re-thread both top and bottom carefully following your Singer sewing machine manual. This fixes many problems.
- Bad Bobbin Winding: Is the bobbin wound too loosely or unevenly? Re-wind the bobbin smoothly. A badly wound bobbin messes up lower thread tension.
- Wrong Needle: Is the needle bent? Is it dull? Is it the right size and type for the fabric and thread? A damaged needle can skip stitches or mess up how thread passes through the fabric. Change the needle often, especially when starting a new project.
- Wrong Needle Insertion: Is the needle facing the right way and pushed up all the way? Check your manual.
- Lint and Dust: Is there lint packed in the tension discs? Is there dust and thread bits in the bobbin area? Clean your machine regularly. Lint in the tension discs stops them from squeezing the thread right. Lint in the bobbin area messes up the lower thread movement. Use a small brush, not canned air (it can blow lint deeper).
- Wrong Presser Foot Pressure: Some machines let you adjust how hard the presser foot pushes down. If it is too high or too low for your fabric, it can affect how the fabric moves and how the threads meet. Your manual will explain this if your machine has this feature.
- Using Cheap Thread: Low quality thread can have thick and thin spots. It breaks easily. This makes getting good tension very hard. Use good quality thread.
If you have tried adjusting tension and checking these other points, and still have problems, check your Singer sewing machine manual for troubleshooting tips specific to your model. Sometimes the machine needs cleaning inside or even a service visit.
Simple Steps for Perfect Tension
Here is a simple plan to follow when you have stitch quality problems:
- Re-thread: Take out both threads. Re-thread the upper thread with the presser foot UP. Put the bobbin back in, making sure its thread is in the bobbin case tension spring.
- Test on Scrap: Get a scrap of your project fabric. Use the same number of layers. Use the same thread.
- Set Upper Dial: Set the upper sewing machine tension dial to a middle number (like 4 or 5).
- Sew and Check: Sew a test line. Look at the stitches on top and bottom.
- Adjust Upper Dial:
- Loops on bottom = Turn dial number UP.
- Loops on top = Turn dial number DOWN.
- Test Again: Sew another line. Check stitches.
- Repeat Step 5 & 6: Keep adjusting the upper dial and testing until stitches look best. This fixes most tension problems.
- Consider Bobbin (if needed): If adjusting upper tension does not fix loops on the top side, and your machine has an adjustable metal bobbin case, you might slightly loosen the bobbin case tension screw (remember to mark it!). If you have loops on the bottom that upper tension won’t fix, you might slightly tighten the bobbin case screw. Adjusting bobbin tension should be a last resort.
- Check Other Things: If tension adjustments don’t work, look at the other troubleshooting points: needle condition, bobbin winding, machine cleaning, presser foot pressure.
Following these steps helps you methodically find and fix the problem.
Tips from the Singer Sewing Machine Manual
Your Singer sewing machine manual is your best friend.
- It shows you exactly how to thread your machine model. This is super important for correct upper thread tension.
- It shows you where the tension dial is and how it works on your specific machine.
- It explains how to insert the bobbin correctly for your machine type (front-load or top-load).
- Some manuals have troubleshooting charts for stitch quality problems.
- It will tell you if your bobbin case tension is adjustable and how to get to it.
Always keep your Singer sewing machine manual handy. It has details specific to your machine that a general guide cannot cover.
Practice Makes Perfect
Adjusting tension might seem hard at first. But it gets easier with practice. Sew test lines on different types of fabric. See how the tension needs change for thin cotton, stretchy knits, or thick denim.
- Thinner fabrics: Might need less tension.
- Thicker fabrics: Might need more tension.
- Stretch fabrics: Tension is very important. Too tight, and the seam will break when stretched. The stitches might look wavy.
Keep your scrap fabric from the project you are working on. Test on that fabric every time you start sewing or change thread. This saves you from having to unpick stitches later!
Learning to adjust tension on your Singer sewing machine gives you control over your stitches. It fixes many common stitch quality problems and stops nasty thread nesting issues. With a little practice, you will get balanced thread tension easily for all your sewing projects.
FAQ Section
How do I know if my tension is correct?
Sew a line on scrap fabric. Look at the top and bottom. The stitches should look the same on both sides. No loops should show on the top or bottom. When you pull the fabric layers apart gently, the threads should lock in the middle.
My machine makes loops on the bottom. What is wrong?
This is very common. It usually means the upper thread tension is too loose. Turn your sewing machine tension dial to a higher number. Make sure you threaded the machine correctly with the presser foot UP. Check that the upper thread is seated right in the tension discs.
My machine makes loops on the top. What is wrong?
This means the upper thread tension is too tight. Turn your sewing machine tension dial to a lower number. If making the upper tension looser does not fix it, and you have an adjustable metal bobbin case, the bobbin case tension might be too tight. You might need to loosen the small screw on the bobbin case a tiny bit.
Should I adjust the bobbin tension screw?
Only adjust the bobbin case tension screw if you have a front-loading metal bobbin case and adjusting the upper tension dial does not fix loops on the top. Use a tiny screwdriver. Make very small turns. Mark the original position of the screw first. For top-loading bobbin systems, you usually cannot adjust this.
What is balanced thread tension?
Balanced thread tension is when the upper thread and lower thread pull evenly. They meet and lock exactly between the two layers of fabric you are sewing. This makes a strong, flat stitch on both sides.
Why do I get thread nesting issues under my fabric?
This tangle of thread underneath usually means the upper thread has no tension at all. This is most often because the machine was threaded with the presser foot DOWN. Or the thread came out of the tension discs. Re-thread the upper thread carefully with the presser foot UP.
Does the type of fabric affect tension?
Yes. Different fabrics need different tension. Thicker or stiffer fabrics might need higher tension. Thin or stretchy fabrics might need lower tension. Always test on your project fabric scrap.
How often should I check my tension?
Check your tension every time you start a new sewing project. Also check it if you change the thread type, fabric type, or needle. Check it any time you start having stitch quality problems.
Can lint affect tension?
Yes. Lint can get stuck in the upper tension discs. This stops them from squeezing the thread right. Lint in the bobbin area can mess up the lower thread. Clean your machine often.
My stitches are wavy on knit fabric. How can I fix this?
Wavy seams on knits often mean the tension is too tight. This pulls and stretches the fabric as you sew. Try lowering your upper tension dial setting. Make sure you are using a stretch needle.