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HOW DO YOU
ADJUST THE BOBBIN TENSION?
Tensions are a common source of problems in sewing. Understanding
how tensions work is essential for every sewing machine user. It is
not as complicated as some believe, and not as simple as some might
think.
Tension is the amount of drag or resistance on the thread as it
moves through the sewing machine. When the tension on top and on
bottom are balanced properly, the threads will join in the middle of
the fabric with no excess thread on top or the bottom of the fabric.
Upper Tension
The thread on the top of the sewing machine is threaded from the
thread spool over and through a series of thread guides, through the
tension assembly (a set of discs with adjustable pressure on the
discs), through the take up spring, through the take up lever, and
finally through the eye of the needle. There are minor differences
in how sewing machines are threaded, but there is amazing similarity
too.
Important:
1. Make sure the thread on the spool is evenly flowing off the
spool.
2. Follow the prescribed thread line through all guides.
3. Look for any abnormality that might snag the thread. Fix it.
4. Always thread the take up spring and take up lever properly.
5. Thread the needle as manufacturer recommends. Most thread front
to back, but some older machines thread right to left or left to
right.
6. ALWAYS thread the machine with the presser foot UP until you are
ready to thread the eye of the needle.
7. Test the thread tension with the presser foot up. Make sure it
easily flows through the machine.
8. Put the presser foot down and thread the eye of the needle.
9. Test the thread flow by gently tugging on the thread. Avoid
bending the needle. You should feel a serious drag on the thread.
10. Lift the presser foot and retest. There should be little or no
resistance.
The upper thread tension is adjusted by tightening or loosening the
tension adjusting knob. You may have been told that on your machine,
the tension is right when the knob says 3 or 4. This is not
necessarily true as we will soon see.
Lower Tension
The lower thread system is even a little more mysterious than the
upper thread system, but it is in many ways even more simple. The
lower thread system may involve top loading bobbins, front loading
bobbins, or even side loading bobbins. Older machines often used
shuttles mounted underneath the machine. While there are a variety
of different designs, the essentials are the same. Thread is wound
on a bobbin (older machines used shuttles the same way). The bobbin
is placed into a case or holder. The thread in the bobbin is drawn
through a tension device and up to the top of the sewing platform.
Important:
1. Be sure you have the right bobbin.
2. Be sure the bobbin thread is properly wound.
3. Be sure to place the bobbin in the bobbin carrier exactly the way
your sewing machine manual says. The bobbin thread usually moves
from left to right or clockwise around the bobbin as it turns.
4. Thread through the lower tension. Usually, this means the bobbin
thread will peal back through the bobbin tension rather than follow
along or just flop in the wind. Notice the piece of metal on top
right of the carrier. A small metal spring usually built into the
bobbin carrier applies pressure or resistance to the bobbin thread.
This is the bobbin tension spring. A tiny screw holds the tension
spring in place. Turning this screw to the right will tighten the
lower tension. Turning it to the left will loosen the bobbin
tension. (“Righty Tighty, Lefty Loosey”)
5. Some bobbin carriers are built in, but many are inserted after
loading the bobbin.
a. In the later case, test the tension by doing the following.
Pull off about six inches of bobbin thread through the tension.
Dangle the bobbin carrier with the bobbin in it while holding
the thread above it. The lower tension should hold the carrier
so that it does not drop. If it does, just turn the screw a
quarter turn to the right. If it does not drop, try bouncing the
carrier a little. If the tension is properly set, the carrier
will drop a little and stop. If it does drop a couple of inches
and stops, all is good. If the carrier does not drop at all even
after pretty good bounce, the tension is too tight. Turn the
screw a quarter turn to the left. Try again.
b. Many machines have a drop in bobbin that fits into a bobbin
carrier below the needle plate. Once the bobbin is placed in the
carrier, the thread is drawn under a tension spring. The same
gentle pull test used in the front loading bobbin can be used
with the drop in bobbin, but it is a bit less precise. If you
continue to experience difficulties with the bobbin tension, it
may be adjusted by turning the small tension screw on the spring
of the bobbin carrier. You may also seek the expert assistance
of your local sewing machine technician if needed.
6. Make sure there are no snags in the thread line after you bring
the thread up through the needle plate hole.
BALANCING TENSIONS
When the thread from the top and the thread from the bottom meet and
form stitches in the center of the fabric with not excess thread on
top or bottom, tensions are said to be balanced.
Think of your fabric like a stream of water. There are two teams
with ropes (threads) tugging in opposite directions. Sew a straight
stitch seam four or five inches long. Look at the thread. Where does
the stitch tie off or connect? Do you see small loops, nubbies, or
other signs of excess thread on the top or bottom of the thread. The
team that pulls the hardest wins the excess thread. If the upper
tension is tighter than the lower tension, excess thread will appear
on top of the fabric. If the bobbin tension is tighter than the
upper tension, you will see excess threads underneath the fabric.
To balance the tensions, simply adjust the upper tension in relation
to the lower tension. If you have tested the bobbin tension as
indicated above, you should not have to adjust the bobbin tension
unless you significantly change the size of thread.
If there is excess thread on the bottom of the fabric, increase the
tension on top by turning the adjustment knob to a larger number
(usually turn clockwise). If there is excess thread on the top of
the fabric, decrease the top tension by adjusting the tension knob
to a lower number (counterclockwise).
If you continue to have tension challenges, take the machine to your
local sewing machine service center for a thorough service.
Important When You Have Tension Challenges:
1. Rethread & Double Check threading.
2. Test lower and upper tensions as you thread.
3. Test sew and adjust upper tension – increase or decrease.
4. Have a professional sewing machine technician service the
machine.
AUTHOR:
Donna Trumble is a professional designer, seamstress, author, sewing
educator, and sewing business owner. She leads several
Sewing Show And Tell groups in her stores guiding participants to
shop sewing machines and learn about sewing and quilting.
David Trumble is a sewing
professional, author, semi-retired minister, sewing machine
technician, and CFO of Temple Sewing And Supply, Inc.
RESOURCE:
For more information on sewing show and tell groups, check out
"Sewing, The World's Greatest Hobby"
by Donna and David Trumble. And check out the local Sew And
Quilt Stores in Killeen, Temple, and Waco, Texas or at
www.sewandquiltstore.com.
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