The doors for the built-in have been done for over a month now. For the last several weeks I’ve been waiting on the hinges to arrive. I can tell you that this is the last time I will special order anything from the particular outfit that I ordered these hinges from.
At any rate, I thought I would snap some shots of how I cut hinge mortises. For some reason, butt hinge mortises seem to intimidate some people. I’m not sure why as they are super easy to do but maybe it’s the thought of cutting a perfect mortise that scares some folks. So here’s my method for cutting hinge mortises. Hopefully it will help someone.
I start by laying out the position of the hinge. I take a really simple approach to this. If you look at the top left picture, you can see how I position my hinges relative to the rails of the door. For the hinges at the top of the door, I align the top of the hinge leaf with the bottom of the top rail. For the bottom hinges, I align the bottom of the hinge leaf with the top of the bottom rail. This usually means that the top and bottom hinges are not the same distance from the top and bottom of the door but I find that the look is better when the hinges are aligned with the rails rather than placed an equal distance from the ends where they may not line up with the rails.
I use the hinge itself to define the length of the hinge mortise with knife lines. I use a try square to extend these knife lines and make sure they are square to the face of the door. I position the hinge on the edge of the door to gauge how far I want the barrel to project past the front of the door and using the hinge as a gauge I make a light mark with my knife to denote the hinge mortise width. I set a marking gauge pin in the knife mark and lock the fence down. I then use this gauge setting to scribe all of the mortises to the same width.
A second gauge is set to the thickness of the hinge leaf and is used to scribe the depth of the hinge mortise on the face of the stile. Care must be taken when scribing the depth not to scribe past the length lines. Since the faces of these doors have already been finish planed, any scribe that goes past the hinge mortise will not be planed away and will show in the finished door. This is not a big deal on the edge since the inside edge of the door will not be seen once it is installed in the cabinet.
I begin the hinge mortise by making short, shallow paring cuts to raise some chips. This is very similar to chopping a joinery mortise, just much shallower. Instead of pounding with a mallet, I hold the blade of the chisel in one hand and I hold the handle of the chisel against my shoulder with the other hand. I push with my upper body weight using my shoulder, not my arms. This offers a lot of control and prevents the chisel from slipping or cutting too far because you are restricting it’s movement with your lower hand. I am actually not left handed but the lighting was better taking the picture in this orientation. I usually place my right hand low, my left hand on the handle and push with my right shoulder.
Once you have a series of chips raised from one end of the hinge mortise to the other, begin lightly paring the raised chips away by working across the grain. At this point I do not work to the full length or width of the mortise. Often times, there is very little material remaining at the back of the hinge mortise and trying to make the mortise full width right away will cause you to break out the back of the door. Also, in order to keep the ends of the mortise crisp, I don’t remove the waste all the way to the ends of the mortise right away, just like making a joinery mortise. I will square up the ends with final paring cuts with the chisel placed right in the knife lines.
The picture below should give you a better idea of what I’m trying to describe. Here’s what the hinge mortise looks like after two or three rounds of raising shallow chips and paring cross grain. The interior of the hinge mortise has been pared clean to final depth but I still need to pare the ends back to final length and I also need to pare the back of the mortise back to the marking gauge line to final width. Cleaning up the interior of the hinge mortise and staying shy of the gauge lines protects the delicate edges of the hinge mortise, especially the long grain at the back of the hinge, which could easliy break out if you’re not careful while making the mortise.
Once you’ve made the final paring cuts with the chisel placed in the scribe lines, your hinge mortise is done. Your hinge should fit tightly in the mortise with just a hair to no wiggle room at all. The precision comes from using the hinge itself to lay out the mortise rather than trying to measure with a ruler. Some folks like to level the hinge mortise with a small router plane but I’ve never foud it necesary. Plus, there is very little material for the plane body to ride on making it very unstable in use.