Machinists love to make things fit perfectly. An example of this is the assembly of a Smith & Wesson K-frame revolver; when the side-plate is put in place and its fasteners done up, no trace of the joint can be felt with a fingernail. Perfect. Traditional old-time machinists literally lay awake at night, thinking of ways to fixture parts to improve accuracy, surface finish, and fit. Clever lads whose mind’s eyes saw farther and more accurately than their elders sometimes discovered that intelligence could get in the way of promotion.