Compliant Locking Pliers - Compliers

I’ve seen plenty of clamp designs that use a screw (including the classic C-clamp design). But I wanted one that would be a bit stronger than those, and that could be placed with one hand. The design I arrived at locks shut using a third link that props the jaws together. It automatically locks, and is disengaged by pressing the trigger (like typical carpentry clamps) while squeezing the handles. These and the trigger are textured for grip. A rubber band provides the force to open the clamp when unlocked.
Of the three primary means of incorporating moving parts in a 3D print (they might be the only three methods…if you know of a fourth, let me know), this design uses all three. It involves mechanical compliance, print-in-place parts, and uses non-printed hardware. The jaws use two compliant mechanisms (depending on how one counts, I guess) to provide both elastic yielding and rotation, ensuring that when the tool is locked, whatever is between the jaws is under significant compression.

The jaws open to as wide as 2”. I have not tested this version to failure, but a previous, weaker version could pinch with at least 15 pounds of force. About 250 g of filament are required with recommended settings. The design does rely on some 45° overhangs and bridges, so be sure you have your extrusion calibrated. The vitamins required are one 1” (25mm) binder clip, about 1” of 1/8” (3mm) steel wire, and a rubber band (optional).

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• Material: I’d recommend PLA or PLA plus.
• Orientation: The yellow side should make the orientation obvious.

• Layer height: 0.2mm. The bridges use 0.6mm gaps, so a coarser layer height might make these fuse together. If you do attempt to scale it down (I haven’t tested this), don’t scale the height because that will change those gaps.

• Walls, Top/Bottom layers: 7-10.
• s: None
• Infill: 50% Gyroid

Assembly:

• Print the main clamp file and the locking link file.

• Open and close the clamp to ensure that the pieces are not fused together. It may take some force, but if there is overextrusion, they might not separate. This is why calibration should be done first.

• Push a short length of 1/8” wire into the central hole to serve as the axle. It is best to lock it in place by fusing the plastic with a hot tool.

• Slide the binder clip onto the locking link and lower jaw by opening the clip partway, getting the clip started into both links, then taking out the wire handles. Then, center the clip on the links.

• Optional - Thread a rubber band through the two holes on the top of the clamp and tie them off to provide tension. This should be tight enough to overcome the force of the binder clip trying to force the clamp closed. This makes it easier to use with one hand.