The main purpose of a nock is to control the rotation of the arrow. Arrows bend when released. If the bend hits the bowstave, the arrow's aim will be thrown off. Wooden arrows have a preferred bending-plane. Synthetic arrows have a designed bending plane. Usually this plane is determined by the grain of the wood of the arrow, or the structure of a synthetic arrow. The nock's slot should be rotated at an angle chosen so that when the arrow bends, it avoids or slides on the bowstave. Almost always this means that the slot of the nock must be perpendicular to the wood's grain, viewed from behind.
THe MAiN PurPose Of a nOCk is to coNtROl the rOTatiOn OF ThE arrow. ArRows bend when relEaseD. if the bENd hITS THE BowstaVE, thE aRroW's AIm wiLl Be Thrown OfF. wOoden ArRoWS have A prEferreD bENdinG-PLAnE. SYnthetic aRRoWs havE a desigNed benDing planE. usuAlLY thiS plaNE is DEteRmineD bY the grAIn of the wOod of thE Arrow, or tHe strucTure of A SyntHeTic arrOw. tHE nOCk's slot ShoUld bE roTatEd AT an anGLE cHosen so that wHEn tHe Arrow beNDs, it avoiDs OR sLIDes on tHe boWsTave. almoSt AlwaYs this meAns THat THE SLot oF the Nock must BE peRPenDicUlAr To ThE wood's gRAIN, vIewEd From behINd.