To properly size and cut a door hinge mortise, you first need to accurately measure the dimensions of the hinge that will fit into the recess. The mortise needs to precisely match the shape and size of the hinge leaf that sits within it.
Here's how to measure the key dimensions needed for a door hinge mortise:
Measuring the Hinge
The first step in measuring for a mortise is to measure the hinge itself. As outlined in the provided reference for a full mortise hinge (also known as a butt hinge):
- Lay the hinge on a flat surface.
- "Measure the height, then the width."
Let's break down what these and other critical hinge measurements mean for your mortise:
Key Hinge Dimensions & Their Mortise Equivalents
Understanding these dimensions is crucial for cutting the correct mortise.
| Hinge Dimension | How to Measure | Relevance to Mortise |
|---|---|---|
| Height | Measure the vertical length of the hinge leaves (along the pin). (As per reference) | Determines the height of the mortise recess. |
| Width (Overall) | Measure the horizontal distance across both leaves when the hinge is fully open. (As per reference) | Helps determine the leaf width, which sets the mortise width. |
| Leaf Width | Measure the width of just one hinge leaf (from the edge to the center of the pin). | Determines the width of the mortise recess. This is typically half of the overall width minus the knuckle's radius. |
| Leaf Thickness | Measure the thickness of one hinge leaf. | Determines the depth of the mortise recess. |
| Corner Radius / Shape | Observe the shape of the hinge corners (square or rounded). | Determines the shape of the mortise corners. |
Once you have these measurements from your specific hinge, you can transfer them to the door and frame when laying out the mortise.
Laying Out the Mortise
Using the measurements taken from the hinge:
- Mark the Height: Transfer the hinge's height onto the edge of the door and the frame where the hinge will be placed.
- Mark the Width: Mark the required leaf width from the edge of the door/frame inward.
- Mark the Depth: Set the depth of your chisel, router bit, or mortising machine to match the thickness of the hinge leaf.
- Mark the Corners: Ensure the mortise corners match the hinge corners (square or rounded).
Accurate measurements of the hinge's height, leaf width, and leaf thickness are essential for a perfectly fitted mortise, ensuring the hinge sits flush with the surface of the door and frame.
