A lockback knife is a type of folding knife that has a special feature: a locking mechanism that holds the blade firmly in place on the handle when the blade is fully extended. The lock can be released to close the knife by depressing the spring-loaded lever on the top edge of the handle. This project is a modern, sleek, slimline design in which the elements are as simple as possible for tooling the parts.
- Skill level:
- Moderately Challenging
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Things you need
- Metal stock such as steel sheeting
- Brass sheet for side plates
- Thin strip of spring steel
- Plexiglass or another durable material for the handle sides
- Metal cutting saws: band saw or hacksaw
- Metal-working files
- Metal rods for pins
- Metal-boring drill and bits
- Rubber cement
- Epoxy--two part mixable
- Emery paper
Copy the template provided here and print it out on paper. (Enlarge the image by left-clicking on it. Then right-click the enlarged image and select "Save Picture As" from the menu that appears. Save it to your desktop or a folder of your choice. The saved image can be opened in an imaging program and printed out.)
Cut out the individual shapes of the parts from the paper, and glue them down on your metal stock using rubber cement. The blade, lock-lever and spacer are all cut from the same metal stock. Cut out the metal following the lines closely EXCEPT the edges of the locking-lever and the end of the blade where they will interlock. Leave an extra thickness of metal on the interlocking edges (about 1/16th of an inch) so that you can later grind and file the excess off, for an exact fit between the blade-end and the locking-lever.
Glue the paper side-plate templates onto the thin brass sheeting and cut them out carefully. Also, cut and shape the spring-steel strip to the right length and thickness to fit into the spacer and touch the lock-lever.
Drill the holes marked by the black circles on the templates. Choose a drill that is the same diameter as the rods that you have chosen for the pins that will hold the assembly together.
File and grind the interlocking edges of the blade-end and locking-lever, checking periodically to ensure that the angles and surfaces match. When the parts fit exactly, the blade can then be sharpened using grinders and metal files. (At this stage, the blade can be hardened and tempered if you wish.)
Assemble all the metal parts together as shown. Cut pins the same length as the thickness of the assembled parts. Pin the assembly together. The spring-steel strip fits into the slot in the spacer and presses up on the lock-lever. Clamp the assembled metal pieces together and file the surface of the side-plates, and any protruding pins, flat.
Cut out the plexiglass or handle material. They will be the same shape as the brass side-plates (but without any holes). Use epoxy to glue the handle material directly to the brass side-plates and let the epoxy harden. Then sand and bevel the edges of the handle material.
With a few finishing touches, such as polishing the blade with emery paper, sharpening with a whetstone and lubing the joint, your locking blade knife is complete and ready to use.
Tips and warnings
- Wear thick workman's gloves when grinding, filing or handling metalstock or parts.
- Secure metal stock firmly with clamps, vice or adequate restraints when cutting or grinding. Wear safety goggles at all stages of the work.
- Use epoxy only in well-ventilated areas.