Threading the Kenmore 158: The Basic Path

The Kenmore 158 threads from the top of the machine down through the tension discs and into the needle. Start with the presser foot up — this opens the tension discs so thread can pass through. Raise the needle to its highest point by turning the handwheel toward you. These two steps matter because a lowered presser foot clamps the discs shut, and a lowered needle can catch thread.

Place your spool on the spool pin at the top right of the machine. If you are using a vertical spool pin (the machine comes with both), push the spool holder onto the pin. Thread the line from the spool to the left, where you will see a small hook or guide on the machine's face. This first guide catches the thread and directs it downward.

From that guide, bring the thread down and to the right into the tension assembly — the metal piece with a slot between two round discs. Push the thread all the way in until you feel it settle between the discs. The thread should sit snug but not pinched. This is where the machine controls how much thread feeds into each stitch.

Key Takeaways

  • Raise the presser foot and needle to their highest points before threading, or the tension discs will stay closed and thread cannot pass through.
  • Thread runs from the spool down through the top guide, then through the tension discs, then down to the needle in a straight vertical path.
  • The thread must sit fully between the tension discs or stitches will be loose and uneven.
  • After threading the needle, pull a few inches of thread toward the back of the machine to seat it properly in the tension assembly.
  • If stitches look loopy or bunched, rethread the entire machine rather than adjusting tension — most threading errors look like tension problems.

Threading From the Tension Discs to the Needle

Once the thread is seated in the tension discs, bring it down and slightly to the left. You will pass through a small metal loop or guide just below the tension assembly — this is the take-up lever. The thread must go through this loop. If you skip it, the machine cannot form stitches correctly.

From the take-up lever, the thread drops straight down toward the needle. On the Kenmore 158, there is usually one more small guide or hook on the machine's face just above the needle. Thread through it, then bring the line to the needle itself. The needle has an eye (the hole) and a groove running down one side. Insert the thread from the front of the machine, pushing it through the eye and letting it rest in the groove.

Pull several inches of thread toward the back of the machine after the needle is threaded. This ensures the thread seats properly in the tension discs and take-up lever. You should feel a slight resistance as you pull — that is the tension assembly gripping the thread.

Bobbin Threading and Winding

The Kenmore 158 uses a drop-in bobbin that sits in a small compartment on the machine's bed, under the presser foot area. Before you wind a bobbin, place an empty bobbin on the bobbin winder spindle, which is usually located on the top right of the machine near the spool pin. Wind the bobbin using the handwheel or the foot pedal, depending on your machine's design.

Once the bobbin is wound, place it into the bobbin case with the thread wound clockwise (the standard direction). The thread end should be at least 4 to 6 inches long. Pull this thread up through the slot in the bobbin case — you will feel it catch slightly as it passes through the tension spring inside the case. This is correct.

After the bobbin is in place and the thread is pulled up, you are ready to sew. The top thread and bobbin thread will lock together under the fabric to form a stitch. If the bobbin thread does not come up when you start sewing, recheck that it passed through the tension spring in the bobbin case.

Common Threading Mistakes on the Kenmore 158

The most frequent error is threading with the presser foot down. When the foot is lowered, the tension discs clamp together and will not accept thread. If you thread this way, the machine will seem to have no tension at all — stitches will be loose and thread may bunch. The fix is straightforward: raise the presser foot, rethread the top, and try again.

Another common mistake is skipping the take-up lever. This small loop below the tension discs is straightforward to miss because it is not as obvious as the larger guides. If you skip it, the thread cannot move up and down as the needle rises and falls, and stitches will be irregular or the thread will break. Always trace the path: spool to top guide to tension discs to take-up lever to needle.

A third issue is not seating the thread fully in the tension discs. If the thread sits on top of the discs instead of between them, it will not be gripped properly. Pull the thread down firmly after it enters the slot between the discs, and you should hear or feel a small click as it settles into place.

Checking Your Work Before You Sew

Before you start sewing, hold the presser foot down with your hand and gently pull the top thread toward the back of the machine. The thread should move with slight resistance — you are feeling the tension discs at work. If it pulls freely with no resistance, the thread is not seated in the discs and needs to be rethreaded.

Next, turn the handwheel by hand (not with the foot pedal) and watch the needle go down and come back up. The bobbin thread should rise up through the needle plate as the needle comes up. If it does not, the bobbin is not threaded correctly or is not inserted all the way into the case. Stop and check the bobbin before you sew.

Make a test stitch on scrap fabric. The stitches should look the same on both sides of the fabric — even tension on top and bottom. If the top thread is loose and loopy, rethread the top. If the bobbin thread is loose, rethread the bobbin. Do not adjust the tension dial until you have rethreaded both paths completely.

Needle Insertion and Alignment

The Kenmore 158 uses a flat-shank needle that inserts into a clamp on the machine's needle bar. The flat side of the shank faces a specific direction — usually toward the back or to the right, depending on your exact model. Check your manual or look at the needle clamp itself; there is often a small mark or groove showing which way the flat should face.

Insert the needle all the way up into the clamp until it stops. Tighten the needle clamp screw firmly but not so hard that you crack the needle. A loose needle will cause skipped stitches and thread breaks. If you are unsure whether the needle is tight enough, try to move it side to side with your finger — it should not move at all.

Replace the needle if it is bent, dull, or has a burr on the tip. A damaged needle will break thread, skip stitches, and snag fabric no matter how well you thread the machine. Needles are inexpensive and wear out with use, so replace yours every 8 to 10 hours of sewing or whenever you notice problems.

Frequently Asked Questions

Why does my thread keep breaking when I sew?

Thread breaks usually come from a needle that is bent, inserted backward, or not pushed all the way into the clamp. Check the needle first: remove it, look at the tip under light, and replace it if you see any bend or damage. Then reinsert it with the flat side facing the correct direction and push it up until it stops. If the needle is fine, rethread the entire machine — a thread caught on a guide or not seated in the tension discs will snap under the pull of sewing.

My stitches look loose and loopy on top. What do I do?

Loose stitches on top usually mean the top thread is not gripping properly. Rethread the top path completely: raise the presser foot and needle, remove the thread, and thread again from the spool all the way to the needle. Make sure the thread sits fully between the tension discs and passes through the take-up lever. Test on scrap fabric before you sew your project.

The bobbin thread won't come up when I start sewing.

The bobbin thread rises when the needle comes up. If it is not coming up, the thread did not pass through the tension spring in the bobbin case. Remove the bobbin, reinsert it, and pull the thread end up through the slot in the case until you feel it catch. You should hear a small click. Reinsert the bobbin and try again.

Do I need to rethread every time I change fabric?

No. You only need to rethread if you change thread color, if the thread breaks, or if you notice stitch problems. Changing fabric weight or type does not require rethreading, though you may need to adjust the needle size or tension dial.

What is the difference between the two spool pins on my machine?

The Kenmore 158 comes with a vertical spool pin (for spools that stand upright) and a horizontal pin (for spools that lay flat). Use whichever matches your spool. The horizontal pin is useful for large spools or specialty threads that unwind better lying down. Either way, thread the machine the same way — the path from spool to needle does not change.