I have a keen interest in the locking mechanisms of an auto. My learning process began with their disassembly .. long before there existed any realistic hope of a successful reassembly. The internet made it easier to access patents & their associated blueprints. Current production has .. in many cases .. migrated toward assembly with threaded fasteners. I'm back to that disassembly exercise .. this time .. with some hope of a functional reassembly.

Starting point.

This little unit .. 3.216" closed .. is a double action Out The Front .. OTF. Inexpensive manufacture in China facilitates retailing @ an affordable $17.00. 

 NOTE: This design inherently results in a loose & wobbly blade. This particular manufacturer minimized that annoying trait. Exacting manufacturing standards appear to have been maintained.

Initial frame separation.

Separating the frame halves provides an initial view of the inside components. The tip of the blade is exposed peeking out from under the left side of the activating mechanism. The rear blade stop of the activating mechanism is firmly seated in its slot @ the rear of the blade .. extreme right. The rear blade latch can be observed engaged in its notch in the blade .. upper frame half on right side @ the 3 27/32" mark. The tension spring that provides the opening & closing energy is readily visible stretched L~R across the top of the activating mechanism.

Activating mechanism removed.

T~B 

T-6 torx tool
Thumb knob
Lower frame half .. to include: 

....................................... blade nested in its machined slots

................................................. stop pin .. floating in hole @ base of blade

........................ fnt & rear blade catches
Activating mechanism.
Top frame half.
Six threaded fasteners. I'll identify the size & thread count @ some pt .. not there yet.
Reference rule.

Blade catch & floating stop pin.

T~B 

Reference rule.
Blade catch for open position.
Spring for blade catch.
Lower frame half.
Blade.
Thumb rest on L .. floating stop pin on R.
Activating mechanism.
Frame top half w/ fasteners.

Exploded view.

Further disassembly exposes the tension spring attached to the fnt & rear blade stops of the activating mechanism .. the pieces with the right angle bend @ their end.

Slot defining blade travel.

L~R

Blade.
Floating stop pin.
Lower frame half .. rear blade catch installed @ 2 & 50/64 " position.
Reference rule.

Floating stop pin & associated slot.

L~R
Floating stop pin .. upper L.
Lower frame half.
Note: centrally located vertical slot defining blade travel
Reference rule.

Slot deformation.

Slot deformation is visible @ the 54/64" mark on rule. A weakness has been identified.

This unit may very well have been open & closed 1000 times since I received it .. 3 days ago. Literally. I took it to wk, gave it to the boys, & invited them to have some fun. I'm personally responsible for 100's of cycles.

The stop pin is a hardened steel pin. The frame is machined aluminum. Every time the blade is opened .. the floating stop pin hammers against the end of the slot which defines the limit of travel for the blade. The harder of the 2 materials is winning ... causing a deformation in the softer material.

Sat 09 Nov (late..r)

Reassembled & functional.

YES !!!

For the purpose of this discussion .. I've identified some parts. I may not be using the proper nomenclature .. just want everyone on the same page. 

NOTE: At about the level of the 2 & 1/8" mark on the rule, there is a notch in the blade. The blade catch drops into this notch to secure the blade in the IN position.

Theory of opening.