Liftplans

The liftplan format of a weaving draft is an alternative to the tie-up and treadling format we have been focused on so far. It has just three components, the threading, the liftplan and the drawdown.

Who needs liftplans?

Liftplan drafts are mainly associated with dobby looms. A dobby can be mechanical or electronic, but its purpose is to select the shafts to be lifted for any given pick. From a handweaver’s perspective, it essentially replaces the treadles on a floor loom and allows the weaver to select many more distinct combinations of shafts.

Because no treadles are involved, a liftplan draft is also a good format for table loom weavers.

Reading a liftplan

Every row in the liftplan corresponds to one weft pick, while the columns correspond directly to the shafts.

You can visualise the rows of the threading and the columns of the liftplan connected by right-angled lines, like this:

So, reading from left to right, the columns of this liftplan correspond to shafts 1, 2, 3 and 4. When a square is coloured in, it indicates that this shaft is lifted for this pick.

As with the treadling, the rows of the liftplan may be read from top to bottom or from bottom to top. Check your draft for any indication of which direction was intended! If we read this liftplan from the top, then the first lift has shafts 1 & 2 raised. This is followed by shafts 2 & 3, then 3 & 4, then 4 & 1. This is the 2/2 twill sequence expressed in liftplan format.

Converting from tie-up to liftplan format

As my dad would say, ‘They have computers to do that.’ And they do. If you have weaving software, then it almost certainly includes the ability to switch between formats simply by selecting the appropriate menu option. However, the human brain can also do this, and it is a useful skill to develop if you want to access a wide range of weaving literature.

Let’s look at the tie-up format again.

Zooming in to the tie-up and the top few rows of the treadling, I have numbered the shafts to help us keep track. We can see that for the first pick treadle one is pressed.

Reading up the column to the tie-up, we can identify which shafts are being lifted by this treadle: shafts 1 & 2.

So in the first row of our liftplan, we make a mark in the corresponding columns.

Moving on to the second pick, we see that treadle two is pressed. Looking up this treadle in the tie-up, we find that it is raising shafts 2 & 3.

So we shade in the squares in columns 2 & 3 of the second row of our liftplan.

And we can continue this process until we have all four picks written in liftplan format.

Once you get into the swing of interpreting a tie-up in this way, you will find that you can weave directly from a draft in tie-up format. However, to begin with it is a good idea to write it out in full. It will help you stay on track when you are weaving and give you a written record you can refer back to later on.

Can I convert a draft from liftplan to tie-up?

This is a trickier proposition. Very often you can convert a draft from liftplan format to tie-up format, and some structures are generally straightforward to handle. 4-shaft twills, for example, use a distinct set of lifts that can be identified and tied up, then treadled in a variety of different sequences.

However, because there are fewer* physical limitations on the number of different lifts you can use when weaving on a dobby or table loom, weavers often come up with designs that use lots of distinct combinations of shafts. If there are too many combinations for the number of treadles you have, then it won’t be possible to convert that draft into a suitable format. This is where that software comes in really handy, as you can see at a glance how many treadles would be needed to weave a draft in tie-up mode.

*On a table loom or a computer dobby loom there are no limits at all! However, if you are weaving on a mechanical dobby loom then the length of the dobby chain has to be taken into account.

 

First posted on weavingspace.co.uk © Cally Booker

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