The purpose of the exercise is not only to find out what treadlings you like but also the ones that work and the ones that won't for the threading you are using. Make careful notes including tagging the corresponding treadlings. You will go back to your sample time and time again.
This is the first in a series of treadling options and tips to be published for 4-shaft overshot. Many of you know the tromp as writ treadling but the first will cover the tromp as writ treadling and my method of treadling to insure that those just starting out will know the way I "think" overshot.
Four-shaft overshot consists of 4 blocks: A = 1 & 2; B = 2 & 3; C = 3 & 4 and D = 4 & 1. The blocks are threaded sequentially, i.e., A, B, C, B, C, D, and share a common thread between sequential blocks. Since looms vary from jack-style, counterbalance or countermarche, it is easier for explanation purposes to work with a direct tie-up, i.e., 1 treadle to 1 shaft. Think of covering the blocks or weaving the blocks when weaving the pattern rather than treadle numbers or treadle orders which really don't mean anything if you don't know what they are tied to. A tabby shot of 1 & 3 and 2 & 4 alternate with pattern shots. And, yes, I weave tabby with 2 feet!
In order to write a tromp as writ treadling for a pattern, begin on the right of the threading and work toward the left. If the A block (1 & 2) has 4 ends, treadle A (1 & 2) 3 times. If the B block is next and contains 6 threads (Remember that they share a common thread/2.), treadle B 5 times. For an example, I will use a jack-style loom since many weave with jacks. In order to weave or cover the A block (1 & 2), lift shafts 3 & 4 and cover or weave A (1 & 2). In essence, you subtract one from the number of ends that are in the block to obtain the number of pattern picks for a particular block. In fact, you can subtract or add picks to "square" the pattern remembering to keep the turning blocks an even number. The reason for this is that overshot pattern picks group together in pairs. When an uneven number of picks are woven in turning blocks, "ghost lines" will appear that look like errors. This is why it is better to write your own tromp as writ treadlings as many books including the book and pattern listed below are written differently.
In this and future treadling options, I will give you the treadling I take to the loom with me for the Mary Ann Ostrander pattern from M. Davison's A Handweaver's Pattern Book, page 146. Balance threading with the first 17 ends.
A1, B1, (C2), B1, A1
D1, (C2), D1
A1, B1, (C2), B1, A1
D1, C1, B1, A3, D3, C5, (B4), (C2), (B4), (C2), (B4), C5, D3, A3, B1, C1, D1
Continue weaving using tabby (1 & 3/2 & 4) and balance with the first 3 lines or follow the draft below and balance with the first 16 pattern picks. Remember to weave with tabby.