Use a Router and a Template

• Templates are available to help countersink a perfect door hinge using a hand-held router. The plastic router template can be adjusted to fit the size of any commercially available hinge. Simply tack the template over the edge of the door or onto the door frame where you want to place the hinge. Insert the correct router bit into the router (usually included with the template) and set the depth so the router bit removes only a thin portion of the door or door frame wood.
  
  Place the router over the plastic template. Start the router (before lowering it onto the wood) and then lower it gently until the blade fits into the template and begins cutting the wood. Follow the outline of the template by keeping the router blade guide pressed against the template. The cutting action takes about a minute to complete. Stop the router and remove it from the template when you've completed the template "circuit."
  
  When you remove the template from the door or door frame, you will have created a perfect countersink in the wood at the proper depth and shape of the door hinge. If you're unfamiliar with using a hand-held router, practice on a piece of scrap wood before tackling your first door.
  
  

Use a Wood Chisel

• Before the days of power tools, craftsmen created countersinks for door hinges using a knife, a wood chisel and a hammer. If you don't have access to a router, try this technique:
  
  Trace around the door hinge on the edge of the door or the door frame with a pencil. Make a mark on the side of the wood surface to indicate how deep the countersink needs to be to accommodate the thickness of the hinge and so the hinge, when installed, will be flush with the surface of the door or the door frame. Score the lines drawn on the wood with a sharp pen knife or razor knife. Press the knife into the wood the depth of the countersink you want to create. Score around the pencil outline of the hinge several times, and then score across the hinge area in a diamond pattern, pressing deeply into the wood to the same depth.
  
  Align the edge of a very sharp wood chisel against the side depth pencil mark. Strike the end of the chisel with a hammer; the chisel will sink into the wood. Pry down on the chisel as you tap the end with the hammer and "walk" the chisel across the wood. The chisel will carve the wood away from the door or the door frame. Because you have prescored the outlines and the interior part of the countersink, the chisel will easily remove wood only in this prescored area.