Brother sewing machine tension is the balanced pull between the upper thread and the bobbin thread that creates a strong, flat stitch on both sides of your fabric. Can you adjust the bobbin tension on a Brother sewing machine? Yes, you can, but it’s usually the last thing you adjust after checking everything else, especially the upper thread tension. Correct tension settings are key for good sewing.
Sewing with a machine means using two threads. One thread comes from the spool on top (the upper thread). The other thread comes from the bobbin underneath (the bobbin thread). These two threads meet inside the machine and lock together in the fabric to make a stitch. If the pull on these threads is not right, the stitches will look bad. This is what we call thread tension problems.
Balancing sewing machine tension means making sure the upper thread and bobbin thread pull with the same force. When the tension is balanced, the threads lock neatly in the middle of the fabric layers. If one thread is too loose or too tight, the stitch will look uneven or messy.
Most times, when you have bad stitches, the problem is with the upper thread tension. Adjusting upper thread tension is simple using the dial or buttons on your machine. However, sometimes the problem is with the bobbin tension. This guide will help you figure out when and how to adjust your bobbin tension on your Brother sewing machine.
Grasping Bobbin Tension
What is bobbin tension anyway? It is the amount of pull placed on the bobbin thread as it comes out of the sewing machine bobbin case. This pull is usually controlled by a small spring and a screw on the bobbin case itself.
Why does bobbin tension matter? It works with the upper tension to form a good stitch. Think of it like a tug-of-war. The upper thread pulls one way, and the bobbin thread pulls the other way. They must pull equally for the stitch to look right. If the bobbin thread pulls too hard or not hard enough, the stitch will be off.
Identifying Bobbin Tension Problems
How do you know if your bobbin tension is wrong? There are clear signs. Troubleshooting sewing machine tension starts with looking at your stitches.
- Loopy stitches on bottom: This is the most common sign of a problem. If the stitches on the bottom side of your fabric look loose and form loops, it usually means the upper thread tension is too tight, or the bobbin tension is too loose.
- Loopy stitches on top: If the loops are on the top side of your fabric, it often means the bobbin tension is too tight, or the upper thread tension is too loose.
- Stitches pulling fabric: If the stitches are very tight and make the fabric pucker or gather, both tensions might be too high.
- Thread breaking: If the bobbin thread keeps breaking, the bobbin tension might be too tight.
- Bird’s nest sewing machine: This is a tangled mess of thread under the fabric, near the needle plate. A bird’s nest is usually caused by problems with the upper thread (not threaded right, tension too loose) or the bobbin (not put in right, thread caught). While often an upper tension issue, incorrect bobbin tension can sometimes play a role or make the problem worse.
Before you touch the bobbin tension screw, always check these things first:
- Is the machine threaded correctly? Re-thread both the upper thread and the bobbin thread. Make sure the presser foot is up when threading the top.
- Is the bobbin wound correctly? It should be wound evenly, not too loose or too tight.
- Is the bobbin inserted correctly into the bobbin case or bobbin area? Check your manual. For drop-in bobbins, make sure it spins the right way.
- Is the right needle in? Is it the right size and type for your fabric and thread? Is it put in correctly? Is it bent or dull? Change it if needed.
- Is the upper thread tension set correctly? Try the default setting first (often around 4 or 5). Sew a test seam. Adjust the upper tension dial one number at a time and test again. Most tension problems are fixed this way.
If you have checked all these things, and you still have thread tension problems, especially loopy stitches on bottom (which hints the bobbin tension might be loose), then you might need to adjust the bobbin tension screw.
When Bobbin Adjustment is Likely Needed
You’ve checked upper tension, re-threaded, changed the needle, and still have poor stitches. When is it more likely a bobbin issue?
- You consistently get loopy stitches on the bottom of your fabric, even after adjusting the upper tension multiple times. This strongly suggests the bobbin thread is coming out too easily.
- You are using a special thick or thin bobbin thread that is very different from your upper thread. This changes the balance.
- Someone else adjusted the bobbin tension before, and it wasn’t put back to the standard setting.
- You have a very old machine, and the bobbin tension spring might have changed over time.
Remember, only adjust the bobbin tension as a last resort. Small turns of the bobbin tension screw make a big difference.
Locating the Bobbin Case and Tension Screw
The first step to adjust bobbin tension is finding the sewing machine bobbin case. On Brother machines, there are two main types:
- Front-Loading Bobbin Cases: These are found on older or some mechanical Brother models. The bobbin case is a separate metal part that holds the bobbin. It loads into a shuttle hook area, usually behind a door on the front of the machine. The bobbin tension screw is clearly visible on the outside of this metal case.
- Drop-In Bobbin Cases: These are common on newer and electronic Brother models. The bobbin drops directly into a spot under the needle plate. The bobbin case is often built into the machine’s bobbin area, and you cannot remove it easily. However, the bobbin tension screw is still located on a removable part. This part is usually a metal or plastic cover plate and spring unit that sits over the bobbin area. You often need to remove the bobbin and sometimes the needle plate to access this part.
We will focus on adjusting the separate, removable bobbin case found in many machines, as it’s the most common type where you directly interact with the bobbin tension screw. The principle is similar for drop-in types, but accessing the screw might differ slightly.
Adjusting Bobbin Tension: Step-by-Step (Removable Case)
This process is for Brother machines with a removable sewing machine bobbin case.
Tools You Need:
- A very small flathead screwdriver. Often called a “jeweler’s screwdriver” or a “precision screwdriver.” The tip needs to fit the small slot on the bobbin tension screw.
- Your bobbin wound with the thread you plan to use.
- Scrap fabric (the same type you are having trouble with).
Steps:
- Turn Off Your Machine: Safety first! Turn off the power switch.
- Remove the Bobbin Case: Open the bobbin door (usually on the front of the machine). Remove the bobbin case with the bobbin inside.
- Find the Bobbin Tension Screw: Look at the outside of the metal bobbin case. You will see a flat spring piece held down by one or two screws. This is the tension spring. There is one small screw on this spring that controls the tension. This is the bobbin tension screw.
- Identify the Starting Point: Note the current position of the screw slot. You can even use a marker or pencil to draw a tiny line from the screw onto the bobbin case. This helps you know the original setting and how much you are turning it.
- Make Small Adjustments:
- To increase bobbin tension (make the thread pull tighter), turn the screw clockwise. This pushes the spring down harder on the thread.
- To decrease bobbin tension (make the thread pull looser), turn the screw counter-clockwise. This lets the spring lift slightly, reducing pressure.
- Important: Turn the screw only a tiny amount at a time. Think of it like the numbers on a clock face. Turn it just like 5 or 10 minutes at a time. Small turns have a big effect.
- Test the Tension (The Drop Test): This is a common way to check if the tension is roughly right.
- Put the bobbin into the bobbin case. Thread the bobbin thread through the tension spring slot on the case. Pull about 4-6 inches of thread out.
- Hold the bob bobbin case by the thread, letting the case hang down.
- Give the thread a slight, gentle tug upwards.
- Correct Tension (Starting Point): The bobbin case should hang without dropping. When you give a gentle tug, it should drop down about an inch or two, then stop.
- Too Loose: The bobbin case drops freely or drops several inches with just the weight of the case itself.
- Too Tight: You can pull the thread hard, and the case barely moves or doesn’t drop at all.
- Adjust the screw slightly and repeat the drop test until you get the “gentle tug equals 1-2 inch drop” result. This test is a starting point, not perfect. The real test is sewing.
- Re-Insert the Bobbin Case: Put the adjusted bobbin case back into the machine. Make sure it clicks or locks into place correctly.
- Re-thread the Upper Thread: Thread your machine’s upper thread path carefully.
- Sew a Test Seam: Get your scrap fabric. Use the stitch type you were having trouble with (usually a straight stitch). Sew a line of stitching.
- Examine the Stitches: Look closely at both the top and bottom of the fabric.
- Are the stitches now balanced? Do they look the same on both sides?
- If loopy stitches on bottom are still there, the bobbin tension might still be a little loose, or more likely, the upper tension needs fine-tuning again now that the bobbin tension is closer.
- If you now have loopy stitches on top, the bobbin tension might be too tight, or the upper tension is too loose.
- Fine-Tune Tensions: Based on your test seam, you might need to make tiny adjustments. Usually, you will go back to adjusting the upper thread tension dial at this point to get the balance just right. Only go back to the bobbin tension screw if stitches are very bad (like severe looping on top, suggesting bobbin is way too tight) after trying the upper tension dial.
Adjusting Bobbin Tension: Step-by-Step (Drop-In Case)
For Brother machines with a drop-in bobbin, you don’t remove a separate case. The bobbin drops into a fixed holder. The bobbin tension screw is usually on a removable cover or piece within this bobbin area.
Steps:
- Turn Off Your Machine: Always turn off the power.
- Remove Bobbin and Needle Plate: Take out the bobbin. You might need to remove the needle plate to get better access. Unscrew the two small screws holding the needle plate or use the lever depending on your model.
- Locate the Tension Assembly: Look in the bobbin area. There is a part (often black plastic or metal) where the bobbin thread passes through a slit or under a small metal finger before going up to the needle. This piece has the bobbin tension screw. It might be held down by a screw you can remove to lift the part slightly, or the adjustment screw might be directly on the part without needing to remove it fully. Check your machine’s manual! The manual will show you exactly where the bobbin tension screw is for your specific model.
- Find the Bobbin Tension Screw: It’s a very small screw, similar to the one on the removable cases.
- Identify the Starting Point: Just like before, note the screw’s position. A photo or mark helps.
- Make Small Adjustments: Use your small screwdriver.
- Clockwise to increase tension.
- Counter-clockwise to decrease tension.
- Turn only tiny amounts!
- Reassemble: Put the cover piece back if you removed it. Replace the needle plate. Put the bobbin back in the correct way (check the thread direction specified in your manual).
- Re-thread Upper Thread: Thread the top correctly.
- Sew a Test Seam: Use scrap fabric.
- Examine Stitches: Check top and bottom. Adjust upper tension first if needed.
Adjusting the drop-in type can be trickier because you can’t do the “drop test” easily. You rely more on sewing test seams and looking at the stitches.
Interpreting Stitch Results After Adjustment
- Stitches look good! Both top and bottom threads lie flat on the fabric, with no loops or visible gaps. The threads lock in the middle. Congratulations! You found the correct tension settings.
- Still loopy stitches on bottom: The bobbin tension might still be a touch loose, OR the upper tension needs to be tightened slightly (usually the latter). Try increasing the upper tension dial by half a number or one number and test again. If that doesn’t work, maybe try another tiny turn clockwise on the bobbin tension screw, then go back to testing with upper tension.
- Now loopy stitches on top: The bobbin tension is now too tight. You need to decrease the bobbin tension slightly (turn the screw counter-clockwise). Turn it back just a fraction. Then, you will likely need to adjust the upper tension again to match.
- Fabric is puckering: Tension is likely too high overall. Try lowering the upper tension first. If it still puckers badly, you might need to slightly loosen the bobbin tension as well.
- Thread is breaking: If the bobbin thread breaks often, the bobbin tension is likely too tight. Loosen it slightly. If the upper thread breaks, it’s usually an upper tension issue (too tight), incorrect threading, or a bad needle.
This process of adjusting bobbin tension and then fine-tuning with the upper tension dial is part of balancing sewing machine tension. It takes patience and practice.
When NOT to Adjust Bobbin Tension
It is worth repeating: do not adjust bobbin tension unless you are sure it is the problem. Most Brother sewing machine tension issues are solved by:
- Re-threading the machine correctly (both top and bobbin).
- Changing the needle.
- Adjusting the upper thread tension dial.
Only if these steps do not fix problems, especially consistent loopy stitches on bottom, should you consider touching the bobbin tension screw. Unnecessary adjustment can make correct tension settings hard to find again.
Maintaining Correct Tension Settings
Once you find the correct tension settings for your machine and common threads, try to keep it there.
- Don’t fiddle: Avoid turning the bobbin tension screw unless necessary.
- Use the same thread in bobbin and top: For general sewing, using the same type and weight of thread in both the bobbin and as the upper thread helps keep tension balanced.
- Clean your machine: Lint and thread bits can get into the bobbin case tension spring and affect tension. Regularly clean the bobbin area. Remove the bobbin case (or needle plate on drop-in models) and use a brush to remove lint.
- Use quality thread: Cheap or old thread can have uneven thickness, causing tension problems.
- Check your manual: Your Brother manual might give a suggested range for your upper tension dial and have specific tips for your model’s bobbin system.
Common Thread Tension Problems and Solutions
Here is a quick look at common thread tension problems and what usually fixes them, putting bobbin adjustment in context.
| Problem | Appearance (Top) | Appearance (Bottom) | Most Likely Cause(s) | Solution Order (Try First) | When Bobbin Adjustment Might Be Needed |
|---|---|---|---|---|---|
| Loopy Stitches | Flat stitches | Loops, loose threads | Upper tension too tight, OR bobbin tension too loose. | 1. Re-thread upper thread. 2. Increase upper tension dial. 3. Check bobbin is in correctly. | If loopy bottom persists after trying 1-3: Slightly tighten bobbin tension (clockwise). |
| Loopy Stitches | Loops, loose threads | Flat stitches | Upper tension too loose, OR bobbin tension too tight. | 1. Re-thread upper thread. 2. Decrease upper tension dial. 3. Check bobbin is in correctly. | If loopy top persists after trying 1-3: Slightly loosen bobbin tension (counter-clockwise). |
| Bird’s Nest | May look okay initially | Huge tangle of thread | Upper thread not seated in tension discs, presser foot up during threading, bobbin issue. | 1. Turn off machine. 2. Clear bird’s nest. 3. Re-thread upper thread with presser foot up. 4. Check bobbin insertion. 5. Check upper tension setting. | If bird’s nest keeps happening despite correct threading & upper tension: Check bobbin winding & insertion; rarely bobbin tension too loose or too tight. |
| Fabric Puckering | Stitches too tight, gathering fabric | Stitches too tight, gathering fabric | Tension (either or both) too high for fabric/thread, wrong stitch length. | 1. Reduce upper tension dial. 2. Lengthen stitch length. 3. Use stabilizer. | If puckering persists after 1-3: Slightly loosen bobbin tension. |
| Thread Breaking (Bobbin) | Stitch may look fine or uneven | May see broken thread bits | Bobbin tension too tight, bobbin wound unevenly, thread catching on bobbin/case, poor quality thread. | 1. Check bobbin winding & insertion. 2. Use better thread. 3. Clean bobbin area. | If bobbin thread keeps breaking: Slightly loosen bobbin tension. |
| Thread Breaking (Upper) | May see broken thread bits or skipped stitches | Stitch may look fine or uneven or skipped stitches | Upper tension too tight, machine not threaded correctly, wrong needle, bad needle, poor quality thread. | 1. Re-thread upper thread. 2. Change needle. 3. Use better thread. 4. Decrease upper tension dial. | Bobbin tension is unlikely to cause upper thread breakage. |
| Skipped Stitches | Stitches are missing periodically | Stitches are missing periodically | Wrong needle, bent needle, needle inserted incorrectly, timing issue (needs repair). | 1. Change needle. 2. Check needle insertion. 3. Use correct needle type/size. | Bobbin tension doesn’t usually cause skipped stitches directly. |
This table is a quick guide for troubleshooting sewing machine tension. Always start with the easy checks before adjusting the bobbin tension screw.
Calibrating Your Bobbin Tension Screw
Once you have found the correct tension settings for your bobbin case, especially after adjusting the bobbin tension screw, it is a good idea to “calibrate” it. This helps you get back to this good setting easily in the future.
You can do this by marking the bobbin case and the screw. Use a fine-tip permanent marker or some correction fluid (like Liquid Paper) to make a mark on the bobbin case right next to the slot on the bobbin tension screw when it is set correctly for standard sewing (usually with mid-weight cotton thread and matching upper tension). This mark acts as your baseline. If you ever adjust the screw for special threads, you can easily return it to this marked position for normal sewing.
Some people even have multiple bobbin cases, each set for a different tension (e.g., one for normal thread, one slightly tighter for very fine bobbin thread, one slightly looser for thicker bobbin thread). However, this is usually not necessary for most home sewers. Learning to make tiny adjustments as needed is often enough.
Fine-Tuning for Different Fabrics and Threads
Even with correctly set bobbin tension, you might need to adjust the upper thread tension when sewing different materials.
- Very light fabrics (silk, chiffon): May need slightly lower upper tension to prevent puckering.
- Very thick fabrics (denim, canvas): May need slightly higher upper tension to ensure the knot pulls into the fabric layers.
- Special threads (metallic, embroidery thread): Might require small upper tension adjustments. Using special needles can also help with these threads.
The bobbin tension, once set correctly for a standard thread, should ideally not need frequent changes. The upper tension dial is your main tool for day-to-day adjustments based on your project.
Balancing sewing machine tension is a dynamic process. You set a good base tension on the bobbin and then use the easily accessible upper tension control to fine-tune for your specific sewing needs.
Common Mistakes When Adjusting Tension
- Adjusting bobbin tension first: This is the biggest mistake. Always try other solutions first.
- Making big turns of the screw: Remember, tiny turns! A quarter turn is often too much. Think eighth or sixteenth turns.
- Using the wrong screwdriver: A screwdriver that is too big can damage the screw slot. One that is too small can slip and scratch the bobbin case or make adjustment hard.
- Not testing after each adjustment: You must sew a test seam after making an adjustment to see the effect.
- Testing on the wrong fabric: Test on the same type of fabric you will be sewing for your project. Different fabrics behave differently with the same tension settings.
- Forgetting to turn off the machine: Always power off before handling the bobbin area or needle.
Troubleshooting sewing machine tension takes practice. Don’t get frustrated. Take your time, make small changes, and test often.
Summing Up Bobbin Tension Adjustment
Adjusting bobbin tension on a Brother sewing machine is a specific step in troubleshooting thread tension problems. It involves finding the sewing machine bobbin case (or the bobbin area tension assembly on drop-in models), locating the tiny bobbin tension screw, and turning it very slightly (clockwise to tighten, counter-clockwise to loosen). This should only be done after confirming the machine is threaded correctly, the bobbin is wound and inserted right, the needle is okay, and adjusting the upper thread tension has not fixed issues like loopy stitches on bottom. Achieving correct tension settings is about balancing sewing machine tension between the upper thread and the bobbin thread. Once you find the right bobbin tension, mark it and rely mostly on adjusting upper thread tension for future projects.
FAQ Section
Q: My stitches are looping on the bottom. Is this always a bobbin tension problem?
A: No. Loopy stitches on the bottom are most often caused by the upper thread not being seated correctly in the tension discs or the upper tension being too tight. Always re-thread your upper thread first (with the presser foot up!), check your bobbin is in correctly, and try adjusting the upper tension dial before touching the bobbin tension screw.
Q: How much should I turn the bobbin tension screw?
A: Very, very little. Think of turning it like the hand on a clock – move it only 5 to 10 “minutes” at a time. Small adjustments make a big difference to Brother sewing machine tension.
Q: Can I just adjust the upper tension to fix loopy stitches on top?
A: Usually, yes. If stitches are looping on top, the upper tension is likely too loose, or the bobbin tension is too tight. Try decreasing the upper tension dial first. If that doesn’t work, then you might need to slightly loosen the bobbin tension screw.
Q: I have a bird’s nest sewing machine situation. Is that bobbin tension?
A: A bird’s nest (thread jam under the fabric) is almost always caused by an issue with the upper thread. Make sure you thread the machine with the presser foot up so the thread sits properly in the tension discs. Also check that the bobbin is inserted correctly. Bobbin tension is rarely the main cause of a bird’s nest, though extreme bobbin tension issues could contribute.
Q: Should the top and bobbin threads be the same?
A: For best results and easier tension balancing, yes, using the same type and weight of thread in the top and bobbin is recommended for general sewing.
Q: I adjusted my bobbin tension, and now I can’t get it right again. What should I do?
A: It can be tricky to find the correct tension settings once they’ve been lost. Try the “drop test” (if you have a removable case) to get back to a basic setting. Otherwise, start with a guess for the bobbin screw position, then use test seams and mostly adjust the upper tension dial to try and find the balance again. If you marked the screw position earlier, that will help a lot. If you still struggle, check your manual for any specific guidance or consider taking the bobbin case to a repair shop to have the standard tension reset.
Q: Will adjusting bobbin tension affect all stitches?
A: Yes, the bobbin tension setting affects all stitch types (straight stitch, zigzag, decorative) because the bobbin thread is used in every stitch formed by the machine.
Q: My Brother sewing machine has a drop-in bobbin. Where is the adjustment screw?
A: For drop-in bobbins, the bobbin tension screw is typically on a removable cover plate or assembly within the bobbin area under the needle plate. You often need to remove the needle plate to access it. Consult your machine’s manual for the exact location and instructions for your model.
Q: How often do I need to adjust bobbin tension?
A: Rarely, if ever, after the initial setting is correct. It’s usually a “set it and forget it” adjustment unless you are using vastly different thread types or notice a consistent issue that upper tension adjustments can’t fix. Regular cleaning of the bobbin area is more important for maintaining good tension.