Hardware:

• 4x m3*16 inset hex screw
• 4x m3 nuts

Tighten bolts until the the grip is firm 

I suggest putting a small amount of machine oil or lithium grease on the areas where plastic rubs on plastic
 

Tighten until you have reached your desired grip strength. Both jaws will stay at a consistent strength no matter which of the 2 bolts are tightened. Loctite threadlocker is optional; i prefer to not use it for future adjustability 

There are additional holes in the jaws to thread in a thin rope for a locked position.

Do not over-tighten- especially if the orange part is PLA. Otherwise, the orange pins keeping the black gears in place, will deform too much, causing the opposite end (the side with no screws) of the orange part to separate, and the increase in diameter from the deformation will press up against the inside of the gears and seize the mechanism

3mm hole on jaws (not the hole for the screw)
 

Print Advice

I printed the jaws with 6 walls, 60% infill, and the body with ABS, 4 walls, 30% infill.
Use a high infill

I also suggest turning on ironing to make the surfaces as smooth as possible.

Depending on your printer, you may need to drill out the screw holes with a 3mm drill bit





0.2mm tolerances; make sure your printer is calibrated well for smooth turning 

Nuts are press-fit

 Edit: i have found that looping a large rubber band around the jaws works really well