I come from a family that includes several engineers and scientists, and have realised recently that "how does it work..." is the first thing that springs to mind when I look at any new machine or device of any kind. It's how I was brought up. The next question being, if it doesn't, how do we fix it? But this is a digression, just to explain my attitude towards looms, and also weave structures.
I've never had the sort of shed Leigh was after on her loom, where all the upper and lower threads are at the same level, although I can get fairly close. I stopped looking for perfection in this respect after someone suggested to me that the important thing was could I pass the shuttle through the warp and weave without problem. But when I saw what Leigh had acheived on her Glimakra, I thought I'd follow the same shed adjustment technique.
It didn't work for me. I ended up adjusting the foremost shafts, and when adjusted they sat lower than the shafts behind, in graduated steps. The loom wasn't balanced anymore, and the shed was no better. So, for now I have reverted to my own technique, which I find good enough. However, if anyone has other suggestions, I be interested to give them a try. (I'm wondering if the texsolv cords on my loom have stretched by different amounts, and if this would make a difference, it had been well used before I bought it.)
The front shafts need to raise or lower less than those behind, as for the same height lifted (or lowered) the thread is shifted more or less relative to the rest of the warp than a thread on a shaft further back. The first shaft lifts at a point about half an inch in front of the second, so threads lifted by these shafts are at a different angle compared to horizontal, etc, and the thread lifted by the 8th shaft is a a significantly different angle. I wish I'd drawn a diagram to show this, hope you can visualise it if you have no loom to play with. This means that the treadle must operate the back shafts before those at the front, and needs to lift the shaft higher for same angle in the warp.
I follow the basic rule that the treadles must be lower at the front. The ties to the back shafts connecting lower lams must have no slack at all, especially at the end nearest the lam hinges. Treadles nearer to the lam hinge have greater leverage (move the shafts more for same distance travelled) and are heavier to operate.
The treadles of the loom hang suspended from the lower lams, and my aim is that the weight should be evenly distributed between the tie cords so they do not alter the balance of the shafts above. It is more difficult to balance the loom if some shafts have more treadles suspended from them than others, and where some shafts hang from only one or two treadles. I have found that the balance is helped by using the two treadles farthest from the lam hinge for plain weave, so every shaft is tied to these two treadles. I've heard said, but needed to make this adjustment yet, that for some patterns it may be necessary to re-arrange the order of treadles compared to the pattern diagram, in order to get a good distribution of ties on the lams.
For the ties to upper lam, I've learnt that no treadle must hang on off just one these ties else it acts to prevent the shaft raising when a different treadle is used. Upper shaft ties need more slack when they are further from the lam hinge. I allow a couple of spare notches in the texsolv cord at the back nearest the lam hinge, increasing to 3 notches on the front of the same treadle, and to three or four on cords of the treadle furthest from the hinge.
I tie-up my treadles by these rules, then check the different treadles are giving reasonable sheds, making small adjustments where necessary. Only small adjustments - large changes set other parts of the system out of balance.
I think that's enough detail for now. Here's a photo showing another of those useful tools that collect around my workshop: a box. Just a nice height to rest the front treadles on while I tie-up. Supported treadles are so, so much easier to tie-up! And I aim to keep them all at about box height when they are tied, although the odd one a bit higher is fine and helps with identifying which treadle is which by feel alone.
The next picture shows where I sit to tie treadles especially since fitting the cloth aprons. I sit inside the loom frame, on the phone book, my legs under the lams and feet resting on the bar across the bottom of the front of the loom. I have to remember to turn my treadle diagram upside down, as it is usually drawn assuming I will be looking at the loom from in front.
I have only just worked out it is easiest to get my hands between the lams and ties if I reach the left arm in between the lams (This is instead of just thrusting my hands toward the point where I want them). I wonder why it took so long to realise this? See next photo. Five lams this side of my arm, the others pushed forwards.
Finally, some weaving. Here's the warp ends tied in small groups (two sets of 8 tied together) at the front apron rod, and then half a dozen rows of contrasting thread have been put through in plain weave, before beating all half dozen together (not after each row as usual) in order to show where the threads are tighter / looser and need adjustment. I thought about tying on larger groups of threads, as the tying and adjusting is tedious. However, small groups keep the warp nicely spread, so it is quicker to get to an even weave when I start putting the weft through.