Thread Tension FAQ

Thread Tensions FAQ

Q. Why do we set thread tension on embroidery machines with the 2/3 – 1/3 rule?

A. "He who knows the theory can make up his own rules."

Embroidery, unlike regular lockstitch sewing is looked at from the front, or
right side. It is undesirable in most cases to see the bobbin thread on the
right side. In regular lockstitch sewing we balance the tensions so the
lockstitch is ideally in the fabric, in most cases top and bottom threads
are the same color when we do lock stitch sewing. In embroidery we want to
look at the pattern of the thread and not see the lockstitching, which is
rough looking. If we balanced the thread in a 50/50 case like regular
lockstitch sewing we would sometimes see the lockstitches and bobbin and
sometimes not. If we adjusted the tensions so the top thread was pulled all
the way around and only a thin line of bobbin ran down the center of the
back of the satin or column stitch the bobbin thread would be easily pulled
out. We need the "zig-zag" to maintain the "lock". In many cases a 60/40
split would be fine, but to be on the safe side most tensions are set with
the 2/3 – 1/3 split. Because tensions will vary, the wider the cast the less
likely the bobbin will be pulled up, the narrower the cast the more likely
the bobbin will show on top, 1/3 became the industry standard. Using a 2/3 –
1/3 ratio in most cases allows us to do a variety of satin widths without
the bobbin showing on top.

So we have two reasons, first we don't want the bobbin to show on top and
second we don't want the bobbin to pull out easily as it would if we set it
with a 95/5 and had a sliver of bobbin on the back.

There are some types of embroidery where we do not use this rule, reversible
embroidery, for those familiar with the American Flag it is a very good
example, the stars are embroidered in a 50/50 ratio, not the 2/3 – 1/3 we
are used to. Want to do a reversible jacket, reset your tensions to a 50/50
(and don't use lettering!).

Earnie also says that Schiffli people feel the tensioning on their machines
is more accurate than on multihead machines. Earnie says that may be true
because in Schiffli work the thread is not twisted as it forms the stitch as
it is in multihead embroidery (or embroidery done with a rotary hook). For
the same reason we use left twist thread as opposed to right twist thread.

Even though your tension may appear balanced with the 2/3 – 1/3 you may have
them too tight or too loose. It is a common mistake to assume that 2/3 -1/3
means good tensions. When the embroidery thread appears loopy or loose or if
the goods pull and distort when removed from the hoop, both can be
indications of tension problems. There are a variety of gauges available to
aid you in setting your tensions; bobbincase gauges are one type.

Having no bobbin showing is not going to give you perfect tensions, but does
increase the likeliness that the embroidery can be easily removed. The
"zig-zag" is needed to maintain the lock. Hand embroidery does not use a
lockstitch produced on a rotary hook machine, unless when you speak of hand
embroidery and mean embroidery moved by hand on a machine or free hand
embroidery. Which in most cases is being done on a rotary hook or shuttle
machine and would have the same tension requirements as a commercial
machine. On very narrow satin or columns we may not see much bobbin thread,
but try to pull one out by slipping a seam ripper under the bobbin thread,
don't cut the thread just pull on it, it can easily slip out of the "lock".

The 2/3 – 1/3 came about due to someone's understanding of the theory and
practice of embroidery using a rotary hook.

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