A prototype for a Leatherman Squirt (PS4) with a liner locking blade.

One thing I really miss from my Skeletool when using the Squirt PS4 is the locking blade. Having a blade that locks is essential for not having it snap shut while your fingers are in the way when you’re doing something that requires a bit of force.

Yesterday however I got an idea for how I could add a liner lock to the PS4. Today I made a prototype, and the system works flawlessly.

The concept behind a liner lock is a metal spring that slips into place when the blade is open and stops it from shutting until the spring is bent back while clsoing the blade. It’s not a very complicated system and so it’s easy to replicate. 20 minutes with a cutting disc on my Dremel and I already had a working system made from the skeleton of my old Squirt P4.

Obviously this isn’t the finished version, as that requires a bit of poilishing. The plan is to move the scales around in order to get a full thickness scale covering the scissors, freeing the thinner scale from the scissors to go on the blade. The scissors are thicker than the blade by default, so doing this will give me more room to work with both because the blade is thinner and because it will then have the thinner scale. Hopefully when the spring is in place the scales will line up again and the added thickness in total will be about a millimeter.

Below is a video of the prototype being put together and tested, as well as some 3D model pics of what I imagine the finished sprig will look like. It will have a small flap on it to make it easier to push back inside.