There is a strong relationship between the fittings on the
spinning wheel and the type of yarn easily produced. This
explains why many spinners have more than one wheel.
The working unit on all modern spinning
wheels is the combination of the flyer (the 'U'
shaped piece) and the bobbin on to which the yarn is wound
as well as the whorl. The bobbin is mounted on
the flyer shaft and rotates independently of the flyer to
wind on the yarn as it is spun. The difference in the rates
of rotation of the flyer and bobbin, dictates the amount of
twist imparted to a length of the yarn. To give control of
the twist, a range of whorls is generally available. The whorl
ratio given is the diameter of the drive wheel compared to
the diameter of the whorl. The smaller ratios are used to
give the low twist for soft yarns from longer stapled fibres,
and the high ratio used for imparting a high twist in short
fibres like cotton and cashmere.
The bobbin should hold at least 100gm of yarn to limit the
number of bobbin changes when spinning.
The drive ratio, measured by the ratio of the diameter of
the driving wheel to the whorl, largely determines the type
of yarn which can be spun easily. For a range of yarns, a
spinning wheel with a wide set of whorl diameters is helpful.
Most softer woollen knitting and weaving yarns can be spun
on all the commonly available wheels which are supplied with
drive ratios in the range 8 to 12:1. Finer yarns require higher
twist and a drive ratio of 14 to 20:1 or more. Bulky yarns
and soft spun yarns of over 1cm diameter require a ratio in
the region of 3 to 8:1.
The size of the flyer orifice can limit yarn plying. It
is important to check this when choosing your spinning wheel.
The flyer is best with an orifice of around 1cm. A larger
orifice gives a tug on the yarn for each turn of the wheel
making fine yarn spinning more difficult. Bulky and complex
plyed yarns need an orifice in the flyer of 1.5 cm or more
as well as larger bobbin and flyer hooks.