Dating furniture 20th century
Keep in mind, wood components can be replaced and this may affect your ability to determine the exact age of a piece.
Feet and chair spindles were also carved individually, so there is no way each one could possibly look identical.
If rough surfaces, plane scrapes, and tool marks are evident inside the piece of furniture, or on the back or bottom surfaces, you're probably looking at a pre-1860 model.
This is one of the easiest ways to provide a fairly accurate date stamp to any antique.
Tool marks and obvious signs of rough cuts are fairly typical with pieces more than 150 years old.
That said, it is important to realize that skilled craftsmen are building furniture by hand even today so you'll want to continue to investigate the age of the piece using at least one other method.