Dräll pulleys and opposite tie-ups, again
So is it possible to use dräll pulleys for other than two-block "opposite" weaves?
To refresh your memory, here is one illustration from my web page on dräll pulleys, with 6 shafts mounted:
The question came up in another context, and I tried to construct some examples.
Starting with a 2/2 twill - this is one "normal" way to thread and tie it up:
As can be seen, that tieup will not work. Starting from the left, the first column will work. The second will not, as shafts 1 and 4 both go up (in the Swe notation), while shafts 2 and 3 both go down). Third column is "opposite", fourth is not.
So what can be done? We need to do something to both column 2 and 4, trying to get them "opposite". One way is this:
Next try, an 8-shaft even tieup (by "even" I mean that all sheds have half of the shafts up, half down, in various combinations - see a discussion on "even" weaves here)
Started with the leftmost column - and got the fourth correct as a bonus.
However much I tried, I could not fix more than 4 columns/treadles.
Maybe I could modify the pattern some, and still like the result? So I marked all the ties that conformed with the rule:
Started to take out/put in ties in the possible positions... this was the best result I could come up with:
Would I weave this? No, but then, I am on a countermarche...
Compare it to my starting point:
I tried various other even tieups with much the same results, and in the end I decided that there is a good reason the pulleys are called "dräll" pulleys: they are excellent for two-block "opposite" structures! For all the others, there are countermarche looms...