The Mechanical Dobby Blues
I was interested to see that you have just produced a video on block weaves. I am doing a block-weave project at the moment, Larissa Gibson's summer and winter coverlet, November/December 2011, p. 62. It is a straightforward design and I have no problems with the weaving. My problem relates to my loom. I have a mechanical dobby that allows a treadling repeat of 50 picks, but that is not enough for the number of picks in a full repeat of this pattern (by far!). I therefore have to peg all eight picks in each of the four block combinations and move through the others (or reverse) to get to the next block combination required. This is terribly tedious!
Please can you give me some advice about using a dobby loom in a better way when one has a very long pattern? Or is this a drawback to dobbies which is not talked about?
Mechanical dobby looms usually have bars, or "lags," like yours. One bar is "pegged" for each weft pick. As you treadle, each bar goes through a box that mechanically raises the shafts for whom "pegs" have been put into corresponding holes in the bar. If you have a fancy twill with a repeat of 24 picks, say, you peg all 24 bars and treadle the pattern without thinking about the treadles you need to use. The drawback to a mechanical dobby is that you really have to peg every pick in the repeat. If you are doing overshot or summer and winter, you could have repeats of 400 or more picks (and you'd have to peg every single tabby pick!), which is essentially impossible. Your solution is as good as it can be with a mechanical dobby loom; you have pegged the summer and winter block combinations and just have to reverse or move through the other blocks after every eight picks.
A better solution, though, is to change your mechanical dobby into a computer-driven dobby. Then, you aren't limited by the threads in the repeat. You simply create the draft in a weaving software program and use a loom driver supplied by the program to tell the loom which shafts to raise for each pick. This does require some expense, a bit of a learning curve, and the occasional pain of problems with electronics.