1/8" is a bit much. Realistically, you will rarely get a shaft that rolls perfectly smooth like an aluminum shaft - that's just the nature of the material. However, I can get them pretty straight with the hand straightening process. I've tried most of the gadgets, and this simply works the best for me, but it takes some practice. It also helps to purchase good quaility shafts, either unfinished or finished arrows, that come pretty straight. If I get a shaft that is really out of wack, I will rarely get it to stay straight.