Machining a Piston from a Casting

[hermetic]

OK Zoot, just re read the thread, you can't drill and machine one boss, then index round and drill the other, they must be drilled then bored in one pass from one side of the piston, or the holes will not be in perfect alignment. Just looked up "boring gudgeon pin holes in pistons" on youtube, the blanks start off with a roughly positioned hole which is bored from both sides at once, but on a cnc machine that level of accuracy is built in! In old manual machining , all bushes or bearing positions that are to recieve a shaft are line bored to ensure alignment and concentricity. It will have to be pretty damn close, even for a Harley;-) (My brother has a road king)