Installing a Half Mortise Lock

The lock body is mortised into the inside of the chest.

hen it comes to selecting a lock for a chest, the choices can be intimidating. As I was looking for a lock for the blanket chest (page 26), I realized there are a lot of options and models to choose from.

But when it comes right down to it, there are really only two styles — full mortise and half mortise. Full-mortise locks are set in a deep pocket cut in the front edge of the chest. The trouble is they can be difficult to install once the case is assembled. That's why I chose a half-mortise lock.

CHOOSING A LOCK. The first thing I look for when choosing a lock is the location of the keyhole on the outside of the case. For my chest, I wanted the keyhole to be centered (top to bottom) on the top rail of the chest. (Most hardware suppliers list the distance from the top edge of the lock to the keyhole pin.)

Another thing to look for is the height (depth) of the lock. If the lock is too deep, it could extend past the bottom of the rail and interfere with the panel. Before building any piece that requires a lock, it's a good idea to have the lock in hand so there won't be any surprises.

LOCK PARTS. The lock set that I chose is made up of two parts: the lock body and the lock link. The lock body is recessed in the inside edge of the case, while the link gets mortised into the lid.

As you can see in the exploded view above, the lock is installed in a stepped mortise. There's a shallow mortise that wraps around the inside back edge for the plate

(back) and up over the top of the rail for the selvedge (top) of the lock. Then there's a deeper mortise, which provides clearance for the cup (or body) of the lock.

The link gets mortised into the lid. Here, two tabs stick out from the link and are grabbed by the lock when the key is turned.

To complete the lock, a key fits through a small hole drilled in the

Measure for drilling keyhole

NOTE: Remove lid and lay chest face down to rout mortise

Repair Damaged Hardwood Floor

NOTE: Remove lid and lay chest face down to rout mortise


NOTE: Oversized mortise prevents lock from bottoming out

Mark and rout a stepped mortise for the cup, again using spacers to support the router. The mortise should be long enough for the lock to sit flush with the top.


NOTE: Oversized mortise prevents lock from bottoming out

Clamp rabbeted block to support router

I vedges^ ^ mortise


NOTE: Set chest upright to rout selvedge mortise

ITurn the chest on its front and trace the lock on the chest. Attach spacers and rout the mortise using a 'A" straight bit. Clean up the edges with a chisel.

Mark and rout a stepped mortise for the cup, again using spacers to support the router. The mortise should be long enough for the lock to sit flush with the top.

3 Flip the chest upright and trace the outline of the top of the lock on the case. Clamp a rabbeted support block to the top and rout the selvedge mortise.

front of the case. And an escutcheon is mounted on the outside of the chest to protect the keyhole.

A half-mortise lock installs in just a few steps. And all it takes is careful layout and a few common tools.

LOCK BODY. The lock is mortised flush to the inside of the chest. Start by marking a centerline on the top of the chest front. Then hold the lock in place with the keyhole on the centerline and trace the outline on the inside of the case.

PLATE. To rout a shallow mortise for the plate of the lock, I first removed the lid and flipped the chest on its front.

Shop Tip: On projects where I'll be removing and attaching the lid several times, I've found that the soft brass screws strip out or break off. To avoid this, I use steel screws until the installation is complete and then replace the brass screws.

To make a wide surface for the router, I attached some hardboard spacers to the rail (Step 1). Then I routed the mortise with a W straight bit, staying just inside the layout lines. For a tight fit, I cleaned up the edges with a chisel.

The next mortise youH rout is for the cup. What you're looking for here is that the lock should sit flush with the top and back of the chest. So I routed the mortise a little longer and deeper than the cup, as you can see in Step 2.

SELVEDGE. With the stepped mortises routed, you can cut the

Placement tabs will create dents for marking and mortising the lid.
ure from top to center of the pin). Drill the hole from the inside.

selvedge mortise. To do this, flip the chest upright and trace the outline of the top of the lock on the case. Again, you'll need to clamp a support block to the top, as in Step 3. (I routed a small rabbet in the block so the top molding would fit inside.)

ESCUTCHEON. At this point, I turned my attention to drilling the keyhole and installing the escutcheon. To mark the keyhole on the chest, press the lock into the mortise. A pin sticking out from the keyhole in the lock marks where to drill. If the pin doesn't stick out past the cup, measure from the top of the lock to the pin, as shown in detail 'a' in the exploded view at left.

and trace the outline on the lid with a sharp pencil or marking knife.
holes for the pins, but wait to attach the escutcheon until after finishing.

To prevent tearout, clamp a piece of scrap to the front of the chest and drill the hole from the inside, as in Step 4. Then file a slot for the bit of the key (Step 5). It's a good idea to test the fit by screwing the lock in place and locking and unlocking it, adjusting the hole as necessary.

LINK. Now you're ready to attach the link to the lid. The easiest way to mark the link mortise is to secure it in the lock and close the lid. Small tabs in the link dent the lid, allowing you to lift the lid and trace the link, as in Step 7. After routing the mortise (Step 8), screw the link in place. All that's left is to reattach the lid. ES

8 Drill a starter hole for the router bit and rout the mortise. Then clean up the mortise with a chisel and screw the link in place.

Chicken Incubator Parts

▼ •▼tic attention to this paneled blanket chest is all of the detail — the sculptural bracket feet, the layered molding at the base, the chamfered corners, the balance of the molded panels and the drawers, and the bullnose lid with its narrow shadow line. All these elements combine to give this piece a really impressive, graceful look.

But don't let all the details intimidate you. This project isn't really very difficult to build. The chest was designed to partner with the bedside chest in Woodsmith No. 139, and like its companion piece, it's all pretty straightforward.

. The large panels are "all cherry plywood so there are -no solid-wood. panels to glue up. The joinery is pretty simple, mostly just tongue and groove or stub tenon and groove. The moldings that provide a lot of the interest to the piece may look tricky, but they're just made with a few "special" router bits.

The only thing that could be a small challenge are the bracket feet But don't worry if you've never made bracket feet. You can find easy instructions in Woodsmith No. 139, or they can be downloaded for free. Or the "ogee" base pictured on page 34 makes a great alternative.

This chest not only looks great, but with two drawers and a nice deep well, it provides plenty of versatile storage space.

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    How to mortise a blanket chest lock?
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