, 19 October 2015 (UTC) 
 ::::* Nice idea, but there's no evidence that Whitney ever did this  (not that it makes any difference to "Ford wasn't the first with interchangeable parts"). 
 ::::: Whitney adopted LeBlanc's idea of standardised parts, which is that all parts would be made to match one standard pattern piece (the idea of "pattern guns" is still over-prevalent in UK armouries). A later development was to not make parts to match another part (which is hard) but to make parts to match a measurement jig (Whitworth takes the credit for that). Yet owing to the limitations of Whitney's (and even Colt's) manufacturing process, such "standard" parts didn't fit together well enough. They were, in Whitney's production, still hand-fitted for final assembly, then grouped into per-gun sets that were kept together. Yes, triggers and locks could be swapped onto other barrels, because all had been made to a standard pattern dimension. But accurately-fitted parts within a lock and sear, or within a barrel group, were still kept together.  What else could Whitney do? He was ahead of the game for basic measurement at this time. There was no precise length measurement, no concept of fit gauges and even surface plates were rare, expensive and somewhat inaccurate (see Maudslay).  
 ::::: Interchangeable parts in the car industry come in with Cadillac, before Ford. They were demonstrated in the famous RAC trial, where two Cadillacs were dismantled, the parts mixed and re-assembled. Cadillac were able to do this (Rolt, Tools for the Job) because they had adopted the more accurate finish grinding for sizing, rather than merely lathe turning.   17:45