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Translating Shafts to Sheds

Three heddles provide a way to translate structures requiring 4 threading positions, or 4 shafts to the rigid-heddle loom. Essentially, a draft is telling you what kind of sheds you need and in what order to weave them. Sheds are created by the threading order and how you lift or lower the warp ends to place certain ends up and others down.

You can weave many 4-shaft structures on two or even one heddle, but there are a certain class of sheds that are easier to achieve with three, such as a 2/2 tie-up or alternating ground and float wefts. You don’t need a three-heddle block to weave with three heddles. One of the heddles can hang in front or behind the heddle as you work.

This post will give you a rough idea of how the translation works, presuming you understand the basic concept of drafting. This post will definitely not give you all the answers you seek, but it may turn on a bulb or two for those who are interested in the relationships between three heddles and four shafts.


Shaft 1 = Front Heddle Hole

Shaft 2 = Middle Heddle Hole

Shaft 3 = Back Heddle Hole

Shaft 4 = Slot

Since shaft looms are based on aligned threadings and rigid heddles aren’t, and that the mechanism to sett and thread the loom are combined on a rigid-heddle, things can get a bit tricky. Not too tricky though, once you can hold these things together in your head. The thread order is determined by the threading of slots and holes and the spacing repeat determines the sett.

Threading Constraints

  • A yarn can only pass through one heddle’s hole.
  • The yarns can’t cross over each other between the heddles.

Here are a couple of examples.

These threading orders are read right to left as they would be placed in a draft set up with the threading in the upper right quadrant, tie-up to its right, and weaving order below the tie-up.

Straight Draw Threading

The structure repeat, the order of the ends to weave any given structure, is 1-2-3-4. The spacing repeat, the cramming sequence that allows you to move the threads in the order they need to be arranged given the constraints of the loom, is 1-3 as seen from the front—1 ends in a hole, three ends in a slot. The spacing repeat in the back is 3-1—3 ends in a slot, 1 end in a hole. The sett density is 200% of the heddle size. If you place the slot position on a stick, you can weave any combination of sheds by lifting the heddle(s) and/or stick up. From this single threading, you can weave structures set up for a straight draw.

Point Draw Threading

This threading is a little more complex. It still uses the same four positions. In order to get the point, you have to do some creative cramming. This threading also includes a balance. The front and back spacing are different, but the overall sett density is 150%. (This structure was used as an example in this post on sett, also linked above.) Once off the loom, the ends will move from the crammed areas into the spaced areas. Again, if you place the slot position on a stick, you can weave any combination of sheds by lifting the heddle(s) and/or stick up.

Things get a little bit tricky with structures that have ground warps such as overshot or crackle. How you approach them can depend on your loom type. Some rigid-heddle loom styles only allow you to pass the heddles to the front of the loom, for example, Schacht and Beka looms. Others allow you to pass the heddles to the front and the back, for example ,Ashford and Kromski looms.

If you want to weave plain weave, typically woven by lifting and lowering the 1 and 3 threading positions, it can be tricky on the looms that only allow you to pass the heddles to the front. David Xenakis came up with a threading that makes the plain weave sheds easier to manage. You simply switch the 1 and 3 positions. Simply is a strong word because depending on how long you have been weaving, your brain may be hardwired to think of Heddle 2 and a “2”, but once you set up the loom with a different threading assignment, the muscle memory of which heddle to lift for which shed can create new muscle memories. This is an important flexibility to develop as a rigid-heddle weaver.

If we use overshot blocks as an example, here are two possible setups. In the standard setup for looms that allow you to pass from the front to the back, you would create the ground warp by passing heddle 1 to the front and 3 to the back, either up or down. In the Xenakis method, you would pass Heddles 1 and 2 to the front, either up or down. The sett density depends on how you lay out the blocks.

   Overshot Blocks Standard Threading

Overshot Blocks Xenakis Threading

When puzzling out a threading, you can use pencil and paper, a drawing program and a stylus, or any word processing program that allows you to draw circles and wavy lines to puzzle out which end goes where to create the four threading positions. Then look to the tie-up section and be sure you can create the various sheds necessary with your loom type.

I get there are whole lot of if, ands, or buts, but in a nutshell, this is how the translation works. The Yarnworker Patreon community—I cannot put into words their awesomeness—and I have spent the majority of 2023 talking about how to warp multi-heddle threading, which is where the rubber meets the road. Every time we drive up a hill there is another vista that awaits.

Here’s to new adventures in 2024!


Liz Gipson Widgets
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