The trade of blacksmithing changed quite a lot through the 19th c. In 1820, a blacksmith would be making door latches and cabinet hinges, axe heads, hoes, and fixing things- welding broken wagon frame brackets, brazing cracked iron pots. One a sub-trade, farriors, would be shoeing horses and oxen. A blacksmith in a very rural part of the country might be doing all of this: he might also be fixing clocks and making wagon wheels, as well, because there would not be enough trade in any one of them.

By 1920, blacksmiths were represented as farriors much of the time: they had been out-competed by factories for the manufacture of hinges, latches, etc, and so shoeing horses and repairing things was something they could still do. However, many of them were also acquiring machine tools- drill presses, lathes, grinders- and so their shops could indeed evolve to become general repair shops. Mines and railroad yards especially would continue to use a forge, along with machine tools in their shops for repair. And many, many farmers would have a small forge and tools for welding wagon rims, doing repairs on their farms. Eventually, though, the oxy-acetylene torch and then the arc welder replaced forges for most welding jobs, and it was possible to have a Ford dealer telegraph an order for a new axle for a Model T, and have it arrive on the train in a day or two. Hammer skills simply just became less important.