I have tried to convert a twill blanket pattern into doubleweave so I can weave it twice as wide as the weaving width on my loom. I found a tie-up for doubleweave, but I am having trouble interpreting various possible treadling sequences. I am a relatively new weaver. Can you recommend a source that would show this in a simplified way? I found a doubleweave draft for four shafts (for a plain-weave blanket), but I am weaving this on eight. I have threaded the loom 1-2-3-4-5-6-7-8 and my warp is all one color. My plan is to use a 12-dent reed with 2 ends per dent with a yarn that would be sett at 12 epi if it were woven in one layer.
There isn’t a specific tie-up and treadling order for doublewide weaving; it depends on your threading (the weave structure you are producing, in your case 2/2 twill, and the way you choose to assign the shafts to the layers). In a doubleweave threading, one end from one layer alternates with one end from the other layer. So since your threading alternates evens and odds, one layer is threaded on shafts 1-3-5-7, the other on shafts 2-4-6-8. (1-2-3-4 would be one layer and 5-6-7-8 the other layer for a 1-5-2-6-3-7-4-8 threading)
The next choice is which layer will weave on top. The Draft shown below places the 1-3-5-7 layer on the top. Now look at the tie-up. I have marked with pink the shafts that are weaving 2/2 twill in the top layer and with green the shafts that are weaving 2/2 twill in the bottom layer. Notice that whenever the bottom-layer twill (green) is woven, the entire top layer must be raised.
The shuttle order for this treadling is to weave across the top, then across the bottom, then back across the bottom (the fold will be where you make that turn on the bottom), then across the top: i.e, top bottom bottom top, throughout.
When you open the blanket, the twill will all be running in the same direction.
There is a great source for doublewide weaving, the Best of Handwoven: Doubleweave, Doublewidth eBook.