Free pattern: Ribbed CSM sock for a 72 cylinder

1. Thread your machine up and get some plain knitting established using waste yarn, enough to ensure it's knitting off correctly and so you can hang weights. I made cast on socks with leftover waste yarn.*
2. Transfer every other needle to the ribber (1x1 rib) - make sure this is also knitting properly. When ready, stop at the 3 o'clock position.
3. Tie on the new yarn, pulling the knot and about 4" of the new yarn through the yarn carrier.
4. Put the heel spring on, and carefully crank one round.
5. Set the ribber to slip, and crank two more rounds
6. Remove the heel spring, put the ribber back into work and set the counter.
7. Knit 30 rounds 1x1 rib
8. Working from the 3 o'clock position, transfer every other ribber needle to the cylinder (3x1 rib)
9. Knit to RC060.
10. Transfer all the ribber needles in the front section of the cylinder (ie from 9 o'clock to 3 o'clock anti-clockwise ) to the cylinder
11. Crank 5 rounds for the pre-heel. As you commence the last round, remove the ribber driving pin and pull all the needles from 9 o'clock to 3 o'clock, plus one extra on each side (clockwise - ie all the needles at the back) into hold position.
12. Put the heel spring on, and pull two needles nearest the yarn carrier into hold, knit 1 round
13. Pull two needles nearest the yarn carrier into hold, knit 1 round
14. Pull 1 needle nearest the yarn carrier into hold, knit 1 round.
15. Repeat step 14 until only 12 needles are left in work - you will need to pull down on the heel to ensure it knits off correctly.
16. Add heel weight. 
17. Put 1 needle nearest the yarn carrier back into work, and hold the latch open as you crank round to it. Knit 1 round.
18. Repeat step 17 until all heel needles are back in work. As you knit the last pass, replace the ribber driving pin and put all of the needles back into work, ensuring all latches on the cylinder are open.
19. Set the row counter to zero and crank for the foot (I use 48 rounds for a UK woman's size 7). For a ribbed sock, I worked 45 rounds 3x1 rib (foot is plain) then transferred the remaining ribber needles to plain and worked a further 3 rounds all plain - makes the grafting of the toe a bit easier.
20. On the last pass, stop at 9 o'clock and put all of the rear needles into hold.
21. Repeat steps 14 - 18, stopping at 9 o'clock on the last pass so that you can return all the held needles into work, ensuring the latches are open (ignore the part about the ribber). 
22. Stop the knitting at 3 o'clock. Leaving a length of yarn for grafting, tie on some waste yarn and pull it through the feeder. Knit at least 10 rounds
23. Repeat steps 2-22 for the second sock.

Notes:

I have my cylinder set to knit as tightly as possible with sock yarn - about 6 on the Imperia. Experiment and find out what works for you. 

If you have small feet width-wise, a plain sock will fit better. 

Cast on sock *

Get some knitting established with waste yarn. Change to leftover sock yarn. Knit 8 rounds, then transfer every other stitch to its neighbour. Knit a further 8 rounds. Pick up the cast on round and hang it on the respective needle. Knit until the sock yarn runs out, or about 20cm of plain knitting. Take off on waste yarn. Unravel the waste yarn and you're done. I didn't bother to cast off; it just curls naturally and has yet to come undone.