Skeleton Tie-Up on a Countermarch?
Is it possible to use a skeleton tie-up on a countermarch loom?
A skeleton tie-up is one in which two (or even three) treadles are depressed together to achieve the shaft combination that needs to rise (or sink) for some or all of the sheds required by a particular draft. Skeleton tie-ups are used when there aren't enough treadles on the loom to form the sheds if they are used one at a time. If a 4-shaft loom has only four treadles, for example, all of the possible sheds can be made by stepping on one, two, or three treadles at a time if they are each tied to one shaft only (also called a direct tie-up).
On a jack loom, you can use two treadles together that are both tied to raise some of the same shafts. For example, one shaft may raise 1-5 and the other 1-8. If I step on both of them, they will raise 1-5-8. The shafts that form the "down" shed, will be all the shafts that are not moved (raised) by the two treadles being used. The problem with a countermarch loom is that all of the shafts must be tied to move to make any given shed. A shaft that is not raised must be tied to go down. So if I step on those two treadles together on a countermarch loom, one of them will be trying to make shaft 5 go down while the other is trying to make shaft 5 go up, and the reverse for shaft 8.
For a countermarch tie-up, you must tie every shaft to move (otherwise you'll have threads in the middle of the shed that go neither up nor down) and you can't ask any shaft to go both up and down. You can tie two treadles so that one of them moves one group of shafts and the other moves the rest, however. I've included here a skeleton tie-up for summer and winter. Treadles 3 and 4 are tied to move only shafts 1 and 2. Treadles 5-10 are tied to move only shafts 3-8. For every pattern pick, treadle 3 or 4 is used with one of the treadles that is not tied to shafts 1 and 2. I couldn't step on any of treadles 5 through 10 withtreadle 1 or 2, and I couldn't use any of treadles 3 through 10 alone.
A plus with this summer-and-winter skeleton tie-up on a countermarch loom is that you don't have to tie every shaft to every treadle (fewer ties!). Unfortunately, it isn't easy to figure out a skeleton tie-up that does work on a countermarch loom for most drafts.