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inertia (i-n-r'sh-auh), in physics, the resistance of a body to any change in its state of motion.
Inertia and Mass
Newton's first law of motion, "An object at rest
tends to stay at rest and an
object in motion tends to stay in motion
with the same speed and in the same
direction unless acted upon by an unbalanced force."
Objects "tend to keep on doing what they're doing." It is the natural tendency of objects to resist changes in their state of motion. This tendency is described as inertia. Because of inertia, an unwinding bobbin can accelerate too rapidly or continue to rotate in the unwinding direction after the thread ceases to be pulled from the bobbin. This results in loosened turns of thread commonly known as "backlash." This backlash is responsible for unsightly looking stitches commonly referred to as loops, bird nests, etc. Backlash or over spin occurs after the take-up
lever has pulled the stitch tight. If allowed, the bobbin would continue to
spin, causing the bobbin thread to be thrown out of the groove in the bobbin,
creating very loose tension as the machine starts up again. Backlash is
undesirable in all types of sewing machines and is especially troublesome with
high speed quilting machines, where many starts, stops and changes in speed and
direction are commonplace.
Important: The less bobbin
inertia that exists, the less bobbin tension is necessary to overcome it.
Mass as a Measure of the Amount of Inertia All objects resist changes in their state of motion. All objects have this tendency - they have inertia. But do some objects have more of a tendency to resist changes than others? Absolutely yes! The tendency of an object to resist changes in its state of motion is dependent upon mass. Inertia is that quantity which is solely dependent upon mass. The more mass which an object has, the more inertia it has - the more tendency it has to resist changes in its state of motion.
Important: SmartBobbin has almost half the mass of the M
Bobbin, therefore, almost half the resistance to changes in its state of
motion during quilting.
How does our
SmartBobbin offer better stitch quality?
The top tension of a sewing machine controls the
quality of the underneath stitch in your quilt, and vice versa the bobbin
tension controls the quality of the stitching that you can see on the top of
your quilt. It is the top thread that is being taken, by your rotating hook,
around the bobbin case (lower thread) and then pulled back up.
Too little top tension will not bring the lower thread far enough, too much will pull the lower thread right through both layers of the quilt. Less bobbin inertia equals less necessary bobbin tension. Less bobbin tension then enables you to quilt with less top tension. The result is the beautiful stitch that is synonymous with all APQS long arm machines.
Why our
SmartBobbin allows the quilter to enjoy a wide variety of thread types:
The top thread passes through the eye of the
needle many times before it finally gets taken up in the quilt. You can see
this for yourself by marking the thread above the needle and watching it as
you turn the machine by hand.
Some thread types bear up to this rubbing through the needle eye much better than others. Lower operating tensions reduce the level of rubbing friction. Lower friction enables you to enjoy the incredibly wide range of thread types that are available today, from the sturdier polyesters to the more delicate and fussy cottons, silks and specialty threads.
The advantages of our SmartBobbin:
In summary: During high speed longarm quilting, our
SmartBobbin has the advantage of less mass. Less mass means less tension is
required to overcome and control the inertia.
Herein lies the secret to our beautiful stitch.
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Copyright Darlene Epp 2001-2009 |
