On some of the dowel arrows I want to make, I plan to try poly tubing. 1/4 " dowel, 1/4" ID tubing, cut a 1" length. Glue on nock end of shaft, halfway. Cut notch in tubing, just enough for string. Smooth with file/sandpaper. Notch stops at wood end, no split it wood. I think that should work well and keep shaft stronger. Will also smooth tubing at other end, taper down a little.