Here is another picture to give you an idea of the thickness of the yarn.
As I explained earlier, the wpi of this yarn are 13-14. With that in mind, I moved on to work out what the sett would be for a twill weave.
CALCULATING MAXIMUM SETT
Turning to Volume 1 of Osterkamp's Winding a Warp & Using a Paddle, page 90 (a very coffee-stained page, I might mention in passing.........), I learn that the first thing I need to do is to calculate maximum sett. To do this, I multiply the wpi by 2/3, or, using a calculator, by the equivalent 0.67. This equals 9.38.
BALANCED WEAVE NOT POSSIBLE
Now, I cannot weave a balanced weave if I use the maximum sett. That is true of tabby, where the maximum sett would be half of the wpi. That is true of twill. The physics of the interlacing simply would not allow for it. If I were to weave a piece at maximum sett I would end up with a warp-dominant piece, not a piece with a balanced sett. Since I do want to weave a balanced weave, I need to adjust this sett of 9.38.
ALLOWING FOR USAGE
In this case, the item is for clothing, but the yarn is also more woolen than it is worsted. That means, according to Osterkamp, that I need to multiply the maximum sett by 65% to 70%. These calculations result in a sett between 6.09 and 6.56.
SETT TO USE
It looks like I am going to sett this handspun at 6 epi. That seems to me a dreadfully wide sett! So I checked Osterkamp's charts in her appendix. There I found a 3-ply wool with a wpi of 15 and a sett of 6 for the kind of item I am going to weave.
Still I am worried. Still this seems wide.
Related Post: Handspun & Computing Sett: Part I