The ratio on a wheel is the ratio of the number of times the flyer goes around (so, the number of twists it puts into whatever length of yarn you've drafted out) for one full rotation of the big wheel (or, one full pedal of the foot treadle-- both treadles, if it's double treadle). So, on a 4:1 ratio wheel (which is LOW), you get 4 rotations of the bobbin/twists into yarn for one full treadle-cycle/rotation of the large wheel. To put it in perspective, "production" wheels typically have 30:1 ratios, and charkas go up to 100:1 ratios or even more.
Now, the amount of twist going into your yarn can vary even at a given wheel ratio, given you might draft out different lengths for a given treadle. So to have constant twist in your singles, you have to develop a wheel rhythm of treadles, drafting, and use the same ratio. But, I digress...
Okay, ratios on my spindle. Well, I vary the ratio on my spindles by picking different spindles -- you see, it's about spindle weight and spindle physics.Lighter spindle == finer yarn. The wheel equivalent would be slower take-up, less drag on the yarn -- minimizing the draw-in of the yarn so you can draft it out more finely.
Then there’s spin time. A long-spinning wider whorl is great for plying – big bobbins would be the wheel equivalent. Not only will the wide whorl spin longer, but it gives you more of a "seat" for your yarn to be wound under (or, for the bottom whorlers, on top of).
And, spin speed! Faster spindle = higher ratios – good for fine spinning and high twist yarns. A faster spindle has some density near the shaft.
Spindles like Bosworth, Tabachek, and Kundert model these "ratio"s wonderfully; Bosworth and Tabachek come in a range of whorl diameters with the shaping of weight out at the rim of the whorl and near the shaft; Kunderts have lovely wide whorls with rim weighting, making terrific long spinners with room for plenty of yarn -- my favorite plying spindle.
Spindlers, too, need to check that the amount of twist going into their yarn stays consistent -- the oomph with which we twist a spindle can give a different spin speed and spin time. I use the ply-back test to check for consistency as I go, as well as unrolling a little from the last spun length to let twist travel between just-spun and most-recently-spun lengths a bit before I wind on. Spindlers develop a rhythm of spindle-twist, drafting, and choice of spindle to spin a consistent yarn.
Are you a spindle-spinner? what sorts of questions do wheel spinners ask you? post a comment on this post here or contact me. Thanks!
Ps. Many thanks to Vicki for vocalizing her thanks for the posts in this blog. It's great to be able to interact with my audience!