In the same vein, the various mortises on the door—the recesses in which the hinges sit or the lockset slides—must be carefully cut out. Too deep and the door won't close properly and might spring open. Too shallow and you'll get creaks and scrapes every time you move the thing. The key to a good mortise is a sharp chisel and a steady but light hand. This is not the time to bang and dig with all your strength.
The good thing about doors these days is that you don't have to spring for the expense of solid wood to get its look and feel. Many doors are made from solid medium-density fiberboard (MDF) or are so-called "solid-core" doors, which means they have a veneer of wood or MDF over a core of particleboard or wood pieces. They're not only better at soundproofing than hollow-core doors but more resistant to warping than solid wood. In fact, MDF is one of the most stable materials you can choose. However, if you intend to use a stain or clear finish on your door instead of painting it, you'll want to get one with solid wood or wood veneer.
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Tape measure and folding ruler
Drill/driver with auger bits
Measure the width of your opening, jamb to jamb, in three places (top, middle,bottom) and the height, threshold to jamb, in three places. Note the largest of each and use these as a guide to buy the door.
2. KNOB SET
A set for a cylinder lock should include two knobs, a spindle, and two round escutcheon plates. For a mortise lock with a bolt, two escutcheons or a long backplate with a keyhole may be required.
Choose between a cylinder lock (a tube-shaped ;acthset with a lock on the knob) or a mortise lock (a rectangular set with a bolt and a skelton key). You can reuse an old lock, but a new mortise lockset might be worth the cost (less than $20) just for the mortise-cutting template that comes with it. Before buying a mortise lock, make sure the distance from the spindle hole to the keyhole matches the one on the backplate you choose, and that the lock body isn't too thick to fit your door.
You will likely need three to hanadle the weight of a solid-wood door or solid-core door. Many doors come with instructions that indicate the size and number needed.
5. LOCK INSTALLATION KIT
If necessary, for drilling for a cylinder lock. Tool companies make these kits, which come with two different hole saws that attach to a drill, along with a jig to guide where the holes go. Some kits also include a drill-mounted router bit and jig for carving out shallow mortises for the lock's faceplate and the strike plate.
6. WOOD SHIMS
To hold the door in its opening as you check the fit and mark for hinges.