Milling machines have been originated from machine tools called rotary files. These machines work inside a lathe and are circular cutters. As hand filing machines were taking too long, these machines were then originally developed.
In between the year 1814 to 1818 the first of the milling machines were developed. The first milling machines were used by two armories named Springfield and Harpers Ferry.
Very soon many private factories started using these machine tools to produce machines products that to quickly than what any number of workers using hand files could do on their own.
There are certain controversies associated with the fact that whether Eli Whitney actually created the first milling machine himself or not.
Certain scholars such as Peter Banda have said that the machine that was credited to Whitney wasn't actually created until after his death. The teens in early part of the 19th century were critical for the development of milling machines.
Major reason for this oversight is Whitney who never envisioned the fact that how far milling machines would be used. Whitney thought that we can use these machine tools as a way to allow workers to not hand file everything.
But he envisioned that there must be a process where the rough parts of the project could be done first by the workers and the rest part can be finished with hand files. It would have been a surprise to know that the idea of hand filling will be eliminated altogether by the machines.
From the 1840s the Lincoln miller was a very influential machine. This was developed by George S. Lincoln & Company who in 1855 made one for the Colt armory.
There is a problem in the miller of having no way to position it vertically. Until the problem was not noticed, the development of machines that had better vertical positioning would not come.