My third frame was a MTB I built in 1985, so far I had been using a metal yard stick, string and calipers to align with. A couple years later having ridden the bike thousands of happy miles, I tore it down to have it repainted by a friend who was working for a local bike factory. I take it over and he says "hey Rich lets check the alignment!" So he sets it up on their alignment table and we start measuring. Well it turns out there is about 12mm of twist in the frame measured along the 30" bar running through the head tube. I leave the frame with him to paint, I built it back up the following week and it rode like sheot. Same frame, same componets, Problem was that I now knew the frame wasn't perfect. I couldn't stand to ride it, so I cut it up with a hacksaw. I soon had a machinist grind me a plate from an old table saw top and I built a new frame working from that. I never let anyone since put my frames on an alignment table. Ignorance is truly bliss.