A concealed sliding bolt for standard North American hollow core doors that is magnetically actuated.

Supplies

1/4 inch Plywood
Small Block of Hardwood
1/4 inch Round Aluminum Rod
3/8 inch Disc Neodymium Magnet
1/4 inch Cube Neodymium Magnet
4 - 1/2 inch #6 Wood Screws
Table Saw
Cordless Drill
Forstner Drill Bits 1/4", 3/8", 1/2", 1"
Standard Drill Bits 7/64", 5/32"
Countersinking Bit
Mini Hacksaw
Utility Knife
Small Wood Chisel
Metal File
Awl
Measuring Tape
Sandpaper
Wood Glue
Hot Glue Gun & Sticks

Step 1: Mill Recess in Door Edge

Print out the template sheet. Cut out the template for the door edge. Fold along the broken lines and attach it with tape at the desired height. Pierce the five drill locations with an awl.

Starting with the 1/2" forstner bit, fold back the template and drill the four corner holes 1/4" deep.

Using the utility knife and chisel, remove the wood between the holes horizontally.

Now using the 1" forstner bit, drill the center hole all the way through.

Finally using the mini hacksaw, utility knife, and chisel, shape the recess to match the last photo.

Step 2: Machine Parts & Build Bolt Assembly

Table Saw Cut List:

1 @ 1 - 1/2" X 9/16" X 1/2" Hardwood
1 @ 1" X 1/2" X 1/2" Hardwood
1 @ 2" X 1 - 3/32" X 1/4" Plywood
1 @ 1 - 3/32" X 1" X 1/4" Plywood
2 @ 1 - 1/2" X 1 - 3/32" X 1/4" Plywood

Round the corners of the mounting plate with sandpaper to match the door edge recess.

Sandwich the 1/2" thick dimension of the longer hardwood piece between the two 1 - 1/2" long pieces of plywood. Make pencil lines 1/2" from both ends of the long dimension of the mounting plate. Center the sandwiched parts between these lines. Cap the other end of the assembly with the remaining plywood piece. Arrange the parts in this orientation on a flat surface. Using wood glue, glue the parts together making sure all joints are flush and square.

After the glue sets up, drill the mounting plate and the other end plate for a single screw as seen in the photo. Use the 5/32" bit, then countersink the holes.

Now using the 5/32" bit, drill two holes 1/4" from the ends of the long dimension of the mounting plate. Then countersink them.

Chuck the 1/4" forstner bit and drill a hole for the bolt pin, centered with the slide channel.

Fine tune the hardwood slide with sandpaper as needed to move freely in the channel.

Cut out the template for the hardwood slide, fold on the broken line, and tape it to the remaining hardwood piece.

Use the awl and mark the hole locations.

Drill a 1/4" hole in the end of the piece 1/4" deep.

Drill a shallow recess for the disc magnet with the 3/8" forstner bit as seen in the photo.

Use hot glue to secure the disc magnet in it's recess.

Cut a 1" length of aluminum rod with the hacksaw, then debur with the file.

Rub candle wax on the hardwood slide, and in the slide channel for lubrication.

Assemble the slide bolt parts as shown.

Step 3: Mount Bolt Assembly

Slide assembly into the door edge recess. Drill pilot holes with the 7/64" bit. Fasten it in with the remaining two wood screws. Test that the bolt slides freely by placing the cube magnet on the face of the door where it interlocks with the other magnet.

Step 4: Drill Bolt Pin Recess

With a portion of the bolt pin exposed, move the door until the pin just touches the door casing. Make a pencil mark centered with the pin. Transfer the mark to the inside face of the door frame. Measure 1" from the door stop and mark intersecting the previous pencil line. Use the 3/8" forstner bit and drill a 3/8" deep recess.