|Frame and panel door from The Practical Woodworker, Bernard E. Jones, ed., showing stiles, rails, panels and the mortise and tenon joinery.|
|Circa 1855 door with two pins securing its tenon in mortise.|
|The faint horizontal lines on this ca. 1853 door were made by the edges of a plane iron when the joiner raised the panels. Note also the square edges on the raised panel field.|
|Although difficult to see under 120 years of encrusted paint, wedges have been driven into the ends of the tenon to secure it in the mortise slot of this ca. 1870 door.|
|The right piece is the stile with a machined cut molding profile. The left piece is the rail with a machine cut coping profile, which is struck as a negative of the molding and fits snugly over the positive profile.|
There are exceptions to this, however, as some plane manufacturers did make coping planes that were paired with door and sash molding planes. These struck the opposite of the molding profile just as machines did. However, these planes are rarely found today, suggesting they weren't used often. When they were used, they were normally used to produce the muntins on windows.
I hope this quick primer will help you determine the age of interior and exterior doors. Knowing these details will allow you select replacements that are appropriate for the age and style of your home. The next step is to select the door configuration, including the number and arrangement of panels, the type of sticking or molding, and the dimensions of the rails and stiles. If you are unsure what configuration you need, consult with a competent professional who is familiar with Victorian homes.