PVC Weaving Tool and Plain Weave Stripes

I had a student at the studio this week.  She is a new weaver and ran into some trouble warping her rigid heddle loom with a pre-wound warp chain.  I wanted her to see how a warp chain was made on a warping board, but I use a warping reel.  This pvc warping "board" was put together from pieces of my pvc niddy noddy/yarn skeiner.   It's one yard long.  Aside from the straight pipe, it uses some T's and one X connector.  PVC is flexible enough that I'm not confident using is as a real warping board, but it worked great to show how a cross is made and how weavers tend to tie the cross in a warp.

The next pretty little piece is on my 8", 4-harness Structo loom.  It's plain weave with a cotton warp of stripes from commercial 8/2 and handspun yarns.  I planned this warp and had to re-do my calculations about three times.  The first issue was one of sett.  My handspun cotton was 18 WPI.  I usually sett plain weave at 1/2 the WPI.  Sara Lamb in her book Spin to Weave describes using a closer sett with a weft that is finer than the warp.  She says that this helps create good drape in a plain weave fabric.  I decided to try it, and recalculated the warp stripes at a closer sett (I ended up using 20 epi, threaded 1-1-2 in a 15-dent reed.)  The next re-calculation was due to concerns with the accent stripes at the edges of the plain weave stripes.  

Theoretically, when plain weave is being woven, a warp thread becomes a dashed line as the weft covers it every other pick.  I didn't want one side of my stripes to have a dash-dot-dash pattern and the other side to have a dot-dash-dot pattern!  I hate to tell you how much I worried about this!  Finally I realized that if my blue stripes were all odd numbers of threads, the purple accent warps would be on the same shed and would always lift together.  Whew!  There was one more related recalculation when I realized that I needed to have the white background in odd numbers of threads as well, otherwise one group would have a pair of dash-dot-dash accents and the next stripe would have a pair of dot-dash-dot accents.  Woo boy!  Well and good, I finally got it all worked out and am happily weaving at the loom.

Guess what I discovered today?!  I made an error winding the warp.  There is one group of white background threads that is an EVEN number of threads.  But check out the woven fabric: it doesn't make a difference in the way the stripes look!  I guess I got all worked up about nothing.  I wonder if it would make a difference in a different piece....maybe if the weft were thicker??