I've designed this door hinge jig to make accurate routing for a standard 76x76mm a breeze. Works on both the door and the frame. Orientation shouldn't matter.

Prerequisites

•    Plunge router
•    30mm bushing
•    20mm routing bit (use a sharp one for best results; mine was a bit dull ;))
•    Standard (in the Netherlands at least) 76x76mm door hinge with rounded corners. I used one by AXA, EAN 8713249109121
•    Some countersunk screws (I used M4x40) to temporarily attach the jig to the door/frame

Good to know

Doors and frames differ in dimensions. You might need to place a shim between the ‘stop’ and the door/frame for the hinge to properly align with the side of the door/frame. 

How to use

1.    Mark the hinge on the door/frame, draw a horizontal center line
2.    Align the jig with the center line (there's a small cutout for that)
3.    Attach the jig with the screws. The screws should not protrude, as that would keep the router plate from freely moving around
4.    Place the router on top and start routing at the required depth
5.    Remove the jig and attach the hinge
6.    Repeat for the other hinges!

Printing instructions

Easy print, standard PLA in 0.20 layer height works well. Print face down. Paint a support on the overhang. Or use the 3mf-file where all of this is already set.