Normally, all primary elements (those directly involved in the knitting action) in the same machine are set to the same gauge. It should be noted that the gauge is measured on one needle bed, so a machine of the same gauge but with two needle beds will have a total of twice as many needles as a machine with one bed. The gauge measured at the point of needle location is the same as that at the point of loop formation.
The pitch, or distance between one needle and another, is proportional to the needle gauge or thickness. The space available, which determines the maximum thickness of the yarn (i.e. the yarn count) that may be knitted, is the gap between the side of the needle and the trick wall as the needle descends to draw a new loop.
Machine gauge can be calculated by dividing the total number of needles into the length of the needle bed. The figure is rounded to the nearest whole number. For example, a 4-inch diameter sock machine has 168 needles. The circumference of a circle is pd where p = 22/7 and d = the diameter. The circumference is therefore 4 x 22/7 = 12.57 inches. The gauge is 168/12.57 = approximately 14 needles per inch. This may be expressed as 'E 14', E being the number of needles per inch.
The diameter of a yarn is proportional to its count, so a relationship exists between the range of optimum counts of yarn that may be knitted on a particular machine and its gauge. Machine gauge thus influences choice of yarn count and affects fabric properties such as appearance and weight.
For a given machine diameter or width, finer gauge machines tend to knit a wider fabric because more wales are involved. Loop sizes will naturally be smaller so more courses of loops will be required per centimetre of fabric knitted and production rates in linear metres of fabric will be less than for a coarser gauge machine.
Also, with more and finer needles there is a higher machine cost and a greater potential for needle damage to occur. A 30-inch diameter single jersey circular machine might have 1716 needles in E 18 and 1872 in E 20.
Coarse gauge machines have needles with larger dimensions and larger needle movements. The knitting cam systems are correspondingly larger, so coarse gauge machines tend to have larger cam boxes and less feed systems around their cylinder than finer gauge machines. It can thus be assumed that machines at the coarse and fine ends of gauge ranges are more expensive to build and operate than machines in the middle of the gauge range.
Originally, needles were cast in small metal blocks termed leads, which were then fitted into a needle bar. In the bearded needle straight bar frame, needles were cast two to a lead and gauged in the number of leads per 3 inches of the needle bar, which is equivalent to a gauge of the number of needles in 1-12 inches. In bearded needle warp knitting machines, needles were cast three to a lead, giving a gauge directly in needles per inch. In the raschel warp knitting machine, the needles were cast in 2-inch leads giving a raschel gauge of needles per 2 inches. Latch needle weft knitting machines normally have a gauge expressed in needles per inch, which in the USA is referred to as 'cut', being short for the phrase 'tricks cut per inch'. As mentioned previously, there is an increasing universal use of the symbol 'E' in warp and weft knitting - for example, raschel E 28 which is 28 needles per inch (25.4 mm). If two needle beds are employed (e.g. V-bed or double-jersey circular machines), the gauge is measured on one bed since the needles in the other bed are to the same gauge unless stated. Also, small diameter single- and double-cylinder hosiery machines have a gauge expressed in the form diameter multiplied by total number of needles, because the number of double-headed needles in a particular cylinder of the double-cylinder machine varies according to the rib set-out.
On some machines it is possible to change the needle beds and camming, and therefore the gauge. The extra spare parts can, however, cost about one third of the cost of a machine. It is also sometimes possible to employ finer or coarser needles than the machine gauge, thus producing finer or coarser knitted stitches. One well-known technique used on the V-bed flat machine is to half-gauge the needle bed by taking every other needle out of action. Thus a machine with 10 needles per inch would become twice as coarse, with only 5 needles per inch. Increasing or decreasing the number of ends of a particular count of yarn will also produce the appearance of a heavier or finer gauge.
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