Friday, August 25, 2023

Table Looms: Understanding Liftplans

Liftplan. It's a word that never made it to my conscious weaving memory, although I vaguely recall it being associated with dobby and computerized looms. Now that I'm learning about table looms, I'm learning new things. Useful things! Such as, rather than refer to a "lever lift sequence," I can just say "liftplan!" 

So what is a liftplan? Most succinctly, it's a draft for direct tie-up looms. 

Draft - weaving instructions for a particular weaving pattern in graph form. Commonly, drafts for handweaving have four parts:

threading - the rows represent the individual shafts (harnesses) of the loom. Columns indicate individual heddles. The threading graph tells the weaver how to thread the loom. 

tie-up - for floor looms with treadles, the tie-up indicates which shafts are tied to which treadles (photos below).

treadling - the order in which the treadles are pushed

drawdown - shows the interlacement of warp and weft threads. If the draft is flipped, so that the threading and tie-up are at the bottom, it's called a drawup. 

How about some photos for my non-weaving friends?

Treadles on a jack loom. Each shaft is connected to
one of the horizontal bars (lamms) above the treadles.

By following the tie-up in the draft, I can choose how to pair shafts with treadles.

Table looms, on the other hand, don't have treadles, but levers.

The levers operate the shafts instead of treadles.

Each lever is connected directly to one
shaft only, hence it's called a direct tie-up.

What all this means is that standard weaving drafts don't apply to table looms or direct tie-up floor looms. So they need to be interpreted differently (see Table Loom: Direct Tie-Up & Reading Drafts). Or better yet, drawn as liftplans.

Liftplan - weaving instructions for table and dobby looms in graph form.

There is no tie-up graph because the tie-up is always the same. 

Tie-up on direct tie-up looms

That means that the treadling graph isn't useful to me. What I need to know, is which levers to engage to create the pattern in the drawdown. As you can see in the liftplan above, that sometimes means engaging more than one lever simultaneously.

Likely, I will be converting drafts to liftplans by hand. Which, in turn, has me thinking about weaving software. If I want to start using weaving software again, I need to find something that will convert a draft to a liftplan, with the additional challenge of finding something I can run on a Linux operating system. And that's another story altogether, but do expect some blog posts about it in the future.


Unknown said...

If you have not discovered yet, you must. You can see a liftplan with the click of a button. There are over 76,000 drafts available there. It’s an incredible resource.

Leigh said...

I've found the website but I haven't yet explored it. It does indeed sound like an incredible resource! Thank you!