Adjustable Ratchet Wrench

The ARW is 3D printed in only two pieces, the handle and head, and both parts can be printed inside the required bounds of 120.65 x 120.65 x 120.65 mm.

The handle simply friction fits onto the head via a dovetail joint and the head contains both the ratchet and adjustable aperture. The head is a printed assembly that consists of seven unique parts: the outer frame, ratcheting ring, aperture ring, pivot arms, adjustable jaws, worm gear, and ratcheting paw.

The ARW was printed out of ABS plastic on a dual-extruder FDM 3D printer (a Fortus 900mc). ABS was chosen for its strength, flexibility, and compatibility with the soluble support material, since the soluble support material was required to properly print the head of the ARW. The flexibility of ABS allowed the ratcheting paw to have a small “spring” printed into it, which allowed it to operate the ratchet properly (see cutaway picture to see the ratcheting paw). The head contains two separate printed-in-place assemblies, the ratchet and the aperture. FDM printer’s ability to create in-place assemblies increases the efficiency of the manufacturing process by removing the need to assemble separate parts. Also, by using a dual-extruder FDM 3D printer with soluble support, more complex assemblies could be made, as seen in the aperture - which contains fourteen moving parts (see picture of ARW with white support material surrounding it).

The outer frame (colored tan in the CAD rendering) connects the head to the handle and holds both the ratcheting ring (colored blue in the CAD rendering) and ratcheting paw (black colored part in the handle of the CAD rendering) in place. The ratcheting ring gives the ARW the ability to operate as a ratchet as well as holds the aperture ring (colored green in the CAD rendering) and pivot arms (colored black in the CAD rendering) in place. The aperture ring rotates inside the ratcheting ring and opens or closes the adjustable jaws (colored red in the CAD rendering). The aperture ring is driven by the worm gear (colored grey in the CAD rendering). The worm gear makes it easy for users to precisely adjust and maintain the aperture's size during use.

In order to best utilize soluble support, small “solvent holes” were added to the second iteration of the ARW to allow the soluble support to be completely dissolved by the solvent. The original design did not contain any solvent holes; therefore, the solvent was unable to reach all of the soluble support and the support got trapped in the aperture ring, preventing it from operating (see picture above).

Another design consideration of the ARW was the layer thickness and moving component tolerances. The ARW was designed to be printed in 0.01 inches thick (vertical, Z axis) layers since the Fortus 900mc was configured to print at even 0.01 inch layers (see picture with dimensions and tolerances labeled). It was particularly important that each part of the ARW was designed in even 0.01 inch increments so that the soluble support would be printed in the correct locations. Leaving a 0.01-0.02 inch gap between moving parts was ideal since it left enough space for soluble support and allowed the parts to move smoothly post print.