I am a big fan of the cable cast-on, but there is one thing that I don't like about it. The edge is neat and sturdy, but it ends in a rounded right-hand corner. I'd like it be square. It's not only that I think a square corner would look better, but the rounding can also make it difficult to sew up that corner neatly.
The cause of the rounded corner dawned on me when I was working out how to do a better intarsia cast-on. Changing color in the middle of the cast-on row shows how the base of each stitch—the bit which gives the rope-like 'cabled' effect—comes not from the stitch itself, but from the following stitch.
Since the final stitch of the row doesn't have a following stitch, it doesn't have a base. Added to this, the penultimate stitch isn't formed properly either—the following stitch sets up the base, but that base isn't pulled downwards and secured in place until the stitch after that is made.
Instead of standing vertically, the final stitch—and hence the base of the previous stitch—lean at an angle, giving the rounded corner.
Fixing the final stitch
I tried a few ways to fix the problem, but my favorite involved casting on an extra stitch to provide a base for the final 'true' stitch. The extra stitch is removed on the first row by knitting the first two stitches together. You have to work this K2Tog on the tips of the needle to avoid making the 'true' stitch too big, but then the extra stitch does a great job of making a neat, square corner.
1. Using the cable cast-on, cast on the number of stitches that you want to knit with, plus an extra one. Here I want my knitting to be 10 stitches wide, so I've cast on 11.
2. On the first row, knit the first two stitches together, working close to the tip of the needles to avoid stretching the final 'true' stitch of the cast-on row.
3. The extra stitch becomes the base of the final stitch.
2. Two rows of stockinette complete, and the right hand corner is square, not rounded.
Square corners make neat joins
With square corners, it's easier to match up two edges for a neat seam. It's also easier to work out where to insert the sewing needle in the first couple of rows for mattress stitch.
And now I love the cable cast-on unreservedly!
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