question: How does a sewing machine bobbin function?
comment: It isn't floating at all, it is put on an axis inside the bottom of the machine, and the case it is inside spins around, to allow the needle to pick it up.
passages: Section::::Production.:Shuttle changes.
  
  The first versions of the White Sewing Machine used a "boat" shuttle that was comparable to those used in contemporary transverse shuttle machines. In 1886 the shuttle was changed to a bullet shape, with a thin rod in the interior upon which the bobbin rotates. The change was probably prompted by the bullet shuttle used in the new Singer Vibrating Shuttle machine, invented the year before, itself a derivative of the White machine. Still later, the shuttle was refined again for the Peerless machines.
  
  Section::::Production.:Badged variants.
   To make one stitch, the machine lowers the threaded needle through the cloth into the bobbin area, where a rotating hook (or other hooking mechanism) catches the upper thread at the point just after it goes through the needle. The hook mechanism carries the upper thread entirely around the bobbin case, so that it has made one wrap of the bobbin thread. Then the take-up arm pulls the excess upper thread (from the bobbin area) back to the top, forming the lockstitch. Then the feed dogs pull the material along one stitch length, and the cycle repeats.
   Section::::Design.:Feed mechanisms.:Manual feed.
  
  A manual feed is used primarily in freehand embroidery, quilting, and shoe repair. With manual feed, the stitch length and direction is controlled entirely by the motion of the material being sewn. Frequently some form of hoop or stabilizing material is used with fabric to keep the material under proper tension and aid in moving it around. Most household machines can be set for manual feed by disengaging the drop feed dogs. Most industrial machines can not be used for manual feed without actually removing the feed dogs.
  
  Section::::Design.:Needles.
   BULLET::::- The brass bobbin yarns are wound on special brass bobbin winding units, with the spools held on jack stands. and then these brass bobbins are compressed by 25% at a pressure of 20 tons per square inch. They are then steamed and cooled. These have to be manually placed in the carrier and held by a spring. The thread needs to be laced to the previous one On depletion of the first bobbin, the whole set is removed and goes through a stripper.
   Besides the basic motion of needles, loopers and bobbins, the material being sewn must move so that each cycle of needle motion involves a different part of the material. This motion is known as feed, and sewing machines have almost as many ways of feeding material as they do of forming stitches. For general categories, there are: drop feed, needle feed, walking foot, puller, and manual. Often, multiple types of feed are used on the same machine. Besides these general categories, there are also uncommon feed mechanisms used in specific applications like edge joining fur, making seams on caps, and blindstitching.
   Section::::Design.:Feed mechanisms.:Drop feed.
   BULLET::::- Bobbin: A small spool of thread inside the rotary hook housing of a sewing machine. The bobbin thread forms the stitches on the underside of the garment. Bobbin thread holds the top embroidery thread to the garment. The bobbin on an embroidery machine works in the same manner and for the same purpose as on a standard sewing machine.
  
  BULLET::::- Digitize: The computerized technique of turning a design image into an embroidery program. Special software is used to create plotting commands for the embroidery machine. The commands are transferred to the machine's logic head by a designated embroidery language.
    In order to create a lockstitch a sewing machine intertwines two threads: an upper thread (descending with the needle into the workpiece from above) and a lower thread (ascending into the workpiece from the bobbin below). To intertwine them, the machine must pass its shuttle (containing the bobbin and the lower thread) through a loop temporarily created from the upper thread.
   The White VS was the first production sewing machine to make use of the vibrating shuttle as a bobbin driver and was introduced in the late 1870s and manufactured with additional improvements up until the early 1900s. The White vibrating shuttle works by loading the bobbin into the shuttle by sliding onto the post.
  
  Section::::Production.
  
  Section::::Production.:Versions.
  
  The White VS evolved over time through these versions:
  
  Section::::Production.:Portable versions.
  
  White developed a 3/4-sized version for the sake of portability, exactly as Singer was developing the 3/4-sized model VS-3/28/128. It was called the 'Peerless' and its evolution tracked that of its full-sized parent:
   BULLET::::- A few older machines have moved their bobbin winders to the high position, but they will still have a mounting lug for it in the original lower position.
  
  Section::::Vibrating shuttle.
  
  The 27 series was Singer's first use of a vibrating shuttle as a bobbin driver, instead of the transverse shuttle design used in the older 'New Family' machine.
  
  Section::::History.
   A track plate is kept at the bottom of the machine. Packages, which supply axial yarns, are kept beneath the track plate. Bobbins are mounted on the carrier, which is pushed by horn gears over the track plate. Braiding yarns are fed from these bobbins. The relative motion of the braiding yarns and the axial yarn determines the pattern and the structure of the braid.
  
  The 3D braiding process is a minor modification of 2D braiding process, where the standing ends are added to the braiding yarns that are moving. The most important 3D braiding techniques are discussed below.
   The rotary hook continuously rotates in place, hooking the upper thread each time its pointed tip passes the 12 o'clock position. Enough upper thread is pulled from above to pass around the bobbin case, which sits loosely inside the hook frame such that loops of thread can pass completely over it. The excess thread, no longer needed, is then pulled back upward by the sewing machine's take-up arm.
   Confusingly, the word doffer (meaning something that takes off, as in "doff your hat") is also used for mill workers whose job it is to remove full bobbins or pirns holding spun fiber and replace them with empty bobbins or pirns. In modern mills, a machine called a doffer may do this task.
  
  Section::::Early years.
   Section::::Design.:Feed mechanisms.:Differential feed.
  
  Differential feed is a variation of drop feed with two independent sets of dogs, one before and one after the needle. By changing their relative motions, these sets of dogs can be used to stretch or compress the material in the vicinity of the needle. This is extremely useful when sewing stretchy material, and overlock machines (heavily used for such materials) frequently have differential feed.
  
  Section::::Design.:Feed mechanisms.:Needle feed.
   The drop feed mechanism is used by almost all household machines and involves a mechanism below the sewing surface of the machine. When the needle is withdrawn from the material being sewn, a set of "feed dogs" is pushed up through slots in the machine surface, then dragged horizontally past the needle. The dogs are serrated to grip the material, and a "presser foot" is used to keep the material in contact with the dogs. At the end of their horizontal motion, the dogs are lowered again and returned to their original position while the needle makes its next pass through the material. While the needle is in the material, there is no feed action. Almost all household machines and the majority of industrial machines use drop feed. 
   Section::::Design.:Feed mechanisms.:Walking foot.
  
  A walking foot replaces the stationary presser foot with one that moves along with whatever other feed mechanisms the machine already has. As the walking foot moves, it shifts the workpiece along with it. It is most useful for sewing heavy materials where needle feed is mechanically inadequate, for spongy or cushioned materials where lifting the foot out of contact with the material helps in the feeding action, and for sewing many layers together where a drop feed will cause the lower layers to shift out of position with the upper layers.
  
  Section::::Design.:Feed mechanisms.:Puller feed.
   The shuttle itself is long and slender, shaped like a bullet, with a pointed tip that is sometimes called the hook. The tip is pointed for the purpose of intercepting the small loop temporarily created (by a brief upward needle motion) in the upper thread—see pictures below of its operation. The bobbin too is long and slender to fit inside the shuttle; in this regard it is very different than the fat rotary bobbins of later sewing machines.
  
  Section::::History.
  
  Although popularized by Singer's 27/127 model series sewing machine, the vibrating shuttle was not invented at Singer.
  
  Section::::History.:Wilson.
   The motors on industrial machines, as with most of their components, lights, etc., are separate, usually mounted to the underside of the table. Domestic machines have their OEM motors mounted inside the machine. There are two different types of motor available for industrial machines: a servo motor (which uses less electricity and is silent when not in use), and the more traditional clutch motor (which is always spinning; even when not in use).
  
  Section::::Social impact.
   The first electric machines were developed by Singer Sewing Co. and introduced in 1889. By the end of the First World War, Singer was offering hand, treadle and electric machines for sale. At first, the electric machines were standard machines with a motor strapped on the side, but as more homes gained power, they became more popular and the motor was gradually introduced into the casing.
  
  Section::::Design.
  
  Section::::Design.:Stitches.
   For embroidered wearable items, the fabric is placed in a hoop. This is then attached to the machine . An X and Y drive mechanism moves the hoop under the needle following the design coordinates created when the design was digitized for embroidery.
  
  Section::::The computerized machine embroidery process.:Embroidering the design.
   Ring-spinning is one of the oldest methods of making yarn. Yarn is fed through the front dating rolls by the pigtail guide to the ring. The ring twirls around the bobbin, wrapping the yarn around the bobbin. The spindle rail moves up and down so that the yarn wraps around the bobbin evenly.
  
  BULLET::::- Rotor-spun
   Lockstitch is the familiar stitch performed by most household sewing machines and most industrial "single needle" sewing machines from two threads, one passed through a needle and one coming from a bobbin or shuttle. Each thread stays on the same side of the material being sewn, interlacing with the other thread at each needle hole by means of a bobbin driver. As a result, a lockstitch can be formed anywhere on the material being sewn; it does not need to be near an edge.
  
  Section::::Design.:Stitches.:Overlock.
   Sewing machines use special needles tailored to their needs and to the character of the material being sewn.
  
  Section::::Design.:Industrial vs domestic.
   Industrial sewing machines are larger, faster, and more varied in their size, cost, appearance, and task. Industrial machines, unlike domestic machines, perform a single dedicated task and are capable of long hours of usage and as such have larger moving parts and comparatively much larger motors. Industrial machines are also more generic; a motor for almost any type of machine can work on any brand. Sewing feet and bobbins between brands are interchangeable. However, with domestic machines the motor, and to a lesser extent bobbins and sewing feet, are brand specific.
   In 1885 Singer patented the Singer Vibrating Shuttle sewing machine, which used Allen B. Wilson's idea for a vibrating shuttle and was a better lockstitcher than the oscillating shuttles of the time. Millions of the machines, perhaps the world's first really practical sewing machine for domestic use, were produced until finally superseded by rotary shuttle machines in the 20th century. Sewing machines continued being made to roughly the same design, with more lavish decoration appearing until well into the 1900s.
  