Sock machines come with a variety of cylinders. The main thing about them is the number of slots -- we say "this is a 72", meaning the cylinder has 72 slots in it. The one shown here is a 72. There are 120, 100, 96, 84, 80, 72, 60, 54, and 48 slot cylinders ... the 80, 72, 60, and 54 are the most common; 120 is really rare!
The cylinder sits inside the cam, and the needles ride up and down the slots of the cylinder to knit the socks. A bit like a geared, extra-slotted, knitting mushroom.
For dimensions, most cylinders have a standard diameter (with small variances) of 4 1/2”, and compound cylinders (rarer) have a working diameter of 3 1/2”. Most Legare 400 and Autoknitter cylinders are interchangeable. The Legare 47 tends to have a slightly smaller cylinder size. Though, older machines can tend to fit only the cylinders that come with them, due to shifting in roundness or size or the hand-machining of them in the first place. So it's best to take very close measurements if you buy a cylinder blind, unless the seller is a knowledgeable sock machine person themselves with the same machine brand and model (and series! I had 3 Legare 400's once obviously from different generations -- I was lucky though, they all swapped cylinders smoothly.)
The number of slots controls the sock size (or, rather, number of needles in the slots). A 72 or 80 slot cylinder uses sock yarn like regia and opal to knit nice adult socks for pretty much any adult – adjust the tension looser for mr. giant feet, tighter for ms. normal foot. A 60 slot or 54 slot can take a slightly thicker yarn (I’ve only tried up to DK weight – the needles tend to split thicker yarns, a real pain!) to knit an adult sock, or stick with sock yarn and a tight tension to knit kids’ socks. The smallest sock I can knit on a 54 at the tightest tension it will reasonably knit fit my daughter’s size 13 (she’s 8 years old, so that’s a kids 13) feet.
The compound cylinders are interesting; at the base they are 4 1/2" in diameter, but they neck-down to 3 1/2" at the top, and have needles with a very long tail-leg so the lifters in the cam can raise the needles. They are useful for toddler and baby socks, and really skinny scarves.
There are also 100 and more slot cylinders, those are useful for very, very fine yarns. I have knit a tube on my 100, but that’s all so far. there’s a cone of zephyr yarn (merino/silk laceweight) in my stash waiting for it … someday!
As for ribbers ... well, that's another post!
In addition to my continued all-time favorite sock-machine eye-candy blog, soxophoneplayer, and the yahoo lists for sock machines, there's now a fun circular sock machine group on ravelry! Join ravelry, and join the fun ... share projects, photos, yarns, and stories.
See the list of posts on sock machines for more.