Wednesday, March 16, 2011

Yamaha BR

The superior quality Yamaha power, single needle lockstitch sewing machine has been more improved now to last for decades.
By thoroughly investigating and modifying the sewing mechanisms in order to achieve low-tension sewing, the machine flexibly responds to various kinds of materials and produces beautiful seams of consistent quality
The mechanism
The lockstitch uses two threads, an upper and a lower. Lockstitch is so named because the two threads, upper and lower, "lock" (entwine) together in the hole in the fabric which they pass through. The upper thread runs from a spool kept on a spindle on top of or next to the machine, through a tension mechanism, through the take-up arm, and finally through the hole in the needle. Meanwhile the lower thread is wound onto a bobbin, which is inserted into a case in the lower section of the machine below the material.
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.
Thread tension correct and incorrect
Ideally, the lockstitch is formed in the center of the thickness of the material—that is to say: ideally the upper thread entwines the lower thread in the middle of the material. The thread tension mechanisms, one for the upper thread and one for the lower thread, prevent either thread from pulling the entwine point from out of the middle of the material.


Of a typical garment factory's sewing machines, half might be lockstitch machines and the other half divided between overlock machines, chain stitch machines, and various other specialized machines.
Industrial lockstitch machines with two needles, each forming an independent lockstitch with their own bobbin, are also very common. There are different types of lockstitch industrial machines. The most commonly used are the drop feed for light and medium duty, and walking foot for medium and heavy duty like the Class 7 with an impressive 3/4" foot lift. This makes the Class 7 able to stitch through heavy materials up to 3/4" with threads as strong as 57 lbs. Originally made by Singer in the US and Europe for supplying the demand of heavy duty clothing for the troops, for many years after the war this class was not available as new because the market was filled. With the outsourcing of many sewing manufacturing jobs, nowadays many Chinese Class 7 machines are available and built by Federal Specifications giving them equal performance to the original ones (FSN:3530-3111-1556, FSN: 3530-3111-3675, FSN: 3530-311-1556, FSN: 3530-3111-3075).
Most industrial lockstitch machines sew only a straight line of stitches. Industrial zig-zag machines are available, but uncommon, and there are essentially no fancy-pattern stitching industrial machines other than dedicated embroidery and edge decoration machines. Even something as simple as a bar-tack or a buttonhole stitch is usually done by a dedicated machine incapable of doing anything else. When a variety of decorative stitching is required rather than a single stitch, a "commercial" machine (basically a heavy duty household machine) is usually employed.

Saturday, August 21, 2010


Info : Another product from the Yamaha BR manufacturer, the Lijia, these sewing machines can make a great variety of plain or patterned stitches. Ignoring strictly decorative aspects, over three dozen distinct stitch formations are formally recognized by the ISO 4915:1991 standard, involving one to seven separate threads to form the stitch. Plain stitches fall into four general categories: lockstitch, chainstitch, overlock, and coverstitch.


Formation of a lock-stitch using a boat shuttle as employed in early domestic machines.
Lockstitch utilising a rotating hook invented by Allen B Wilson. This is employed on many modern machines.
Formation of the double locking chain stitch.
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. Stitch making : The drive shaft has a vertical crank attached to it, going down under the base plate. Again, by a series of levers, this connects to a hook ring. The hook ring picks up the upper thread and guides it round the bobbin holding the lower thread. Using the up and down movement of the needle and the rotation of the hook ring the two threads are looped together to form the stitch.

Thursday, January 1, 2009

StarKing BR

A built in lock stitch feature on a sewing machine, sews a certain number of stitches and then stops sewing. This option is available on many newer, electronic sewing machines. Quilters use this feature to secure quilting stitches without having an unsightly back-stitch visible on their quilts. A lock stitch is also used on sheer fabric and fabric that tends to have a large amount of sweeping drape, since back stitching could interfere, even in a small way, with the natural drape of the fabric.
  • On a sewing machine that has a built in lock stitch feature, refer to your sewing machine manual.The lock stitch feature sews the same single stitch backward and forward without numerous stitches repeated.
  • On a sewing machine that does not have a built in lock stitch feature, you can achieve the same result by shortening the stitch length to as short as possible and sewing two to four stitches in that one spot. More than that is apt to jam the machine and create an unsightly thread knot.
  • It is also possible to stop the sewing machine stitching, leave a thread tail and then pull one tail to the back side and hand knot the thread tails tight to the fabric.