Centering the Warp
I have a Leclerc loom which divides the shafts in half at the centre with a support that is about .25 of an inch wide. This separates the heddles on each side thereby prohibiting uninterrupted threading across the shaft. I am presently threading a striped pattern alternating a twill and a plain stripe. My problem is that the center of the warp occurs in the centre of the twill pattern which means that the center divide interrupts the pattern. I am tempted to complete the pattern threading on one side but that will mean that the warp is not exactly centered. What would be your solution?
Most of my looms also have some support system for the spring steel rods or cords of some kind that divide the warp in the center of the shaft (or, more commonly, off center). Usually, this splitting of the warp threads at the shafts is completely erased as the warp reaches the reed, so it doesn't matter if it comes in the middle of a stripe. It also doesn't really matter if the warp is perfectly centered on the loom. In some cases, though, depending on how the loom is constructed, if the warp is very much off center, the shafts themselves may not rise/lower smoothly. So centering is good, but doesn't have to be exact. You do want the warp to go straight from front beam to back beam, though, so that the split at the shafts from those supports does not pull the threads in one direction or the other. If this happens, the heddles may rub on the threads and abrade them.
I think you are fine to separate the heddles in the middle of that stripe.