Between the zig and the zag

I received some very nice comments on my zigzig swatch recently posted on the O! Jolly! Facebook page. I knitted that particular swatch on a Dubied v-bed hand flat machine in my Knit Design Principles and Technology class.  I decided to duplicate it on my Passap machine at home.

A funny thing happened. Instead of getting a stitch pattern like this:

Crisp, well-defined zigs and zags; parallel ladder rungs (from the needles left out of work)

I got this:

Mini zigzags and crisscrossed ladder rungs

Big difference? Yeah.

I remembered that the Passap knitting machine manual provided a version of this racking technique, so I decided to research my mistake there. The knitting instructions were virtually the same as my instructions from class. The mistake must be in my knitting.

Basically, the pattern is this: In full fisherman's rib (a/k/a full cardigan) *Knit 1 row, rack 1 needle in one direction; knit 1 row, rack back;* repeat a bunch of times, then knit 1 row, rack a needle, knit 1 row don't rack back. This creates the zig. To create the zag, just start from the beginning. 

Honestly, I still don't quite know where I made my mistake. I barely understand why this creates a zigzag. I turned to my bible a/k/a Susanna E. Lewis & Julia Weissman's A Machine Knitter's Guide to Creating Fabrics:

...in the horizontal herringbone pattern; if you rack one needle left, then one needle right with one row between rackings, the stitches on both faces of the fabric will slant in the same direction, and create a bias fabric. To change the direction of the bias, knit one row without racking after it, to put the carriage on the opposite side and break the sequence....

I reknitted and got this:

Yes, what I wanted!

This is not one of those posts where I present a problem and then happily provide a solution. I'm just beginning to understand why racking "one needle left, then one needle right with one row between rackings" creates a bias. It bugs me that I don't know where I made my error the first time. I do believe that I did the non-racking row correctly. But I am getting a clue to my error from information presented later on in the racking chapter of the Lewis/Weissman book. My guess is that I must pay more attention to the relationship between the direction I rack and the bed on which I tuck. In other words I may have been too sloppy in translating directions. It's not just racking "one direction;" it may depend on where the tucks are. Or maybe not.

Any serious machine knitters reading this? Your comments would be very much appreciated.