I have an AVL with flying shuttles. The shuttles use a pirn that is wound on an electric bobbin winder. When I want to increase my yarn thickness by using two (or more) threads together for weft, even if I wind the bobbin very carefully, the two threads separate and do not turn smoothly together at the selvedge. Do you have any idea how to better wind the pirns to avoid this happening?
This problem also occurs with regular boat shuttles. When two strands are wound together on a bobbin, they usually don’t unwind evenly and therefore cause trouble at the selvedges. Over the years I have heard of two solutions. One is to ply the two strands together on a spinning wheel. The other is to rig up a stand that allows you to put one of the two weft cones above the other and bring the thread from the bottom cone up through the center of the top cone and then wind the two threads together. I tried this second solution but found that it did not worked for me.
Depending on the project, I have used two different approaches to this problem. One is to simply weave two picks in the same shed (using floating selvedges). That means twice as many throws of the shuttle, but it is much faster and more pleasant than fiddling with the selvedges on each pick.
The other is to use a 2-bobbin shuttle (it’s hard to imagine a flying shuttle that could take two pirns!). Managing this shuttle takes a bit of practice at first, but you soon learn to throw it with just the right force to turn the two threads together.
I’m not sure what would work best for more than two threads. I own a 3-bobbin shuttle (mostly because I adore tools), but I haven’t used it yet; managing it would require some practice!