Adjustable Ratchet Wrench

grabcad

I am currently a student at The University of Alabama in Huntsville and I designed the adjustable ratchet wrench (ARW), a redesign and combination of a ratchet and adjustable wrench. Ratchets and adjustable wrenches are both common tools used to tighten or loosen nuts and bolts. Both have unique advantages and disadvantages associated with them.Primary advantages and disadvantages of ratchets and adjustable wrenches:- Ratchets allow the quick tightening or loosing of bolts since the ratchet can be left on the bolt and simply rotated back and forth in order to tighten or loosen the bolt.- Ratchets unfortunately require a different socket for each unique size of bolt they are to be used on. This includes unique sets of sockets for metric and standard sizes.- Adjustable wrenches are slow and tedious to use since the wrench must be removed from the bolt each time the bolt is to be rotated. Also, with an open end, it is easy for adjustable wrenches to slip off bolts.- Adjustable wrenches can be used on any size bolt within their given range. They are also able to fit both metric and standard bolt sizes.The ARW combines the advantages of the ratchet and adjustable wrench and solves each of the respective disadvantages. The ARW features a ratchet with an adjustable "aperture" that can be sized to fit any size of bolt within the range of 17 to 49 mm (~5/8" to 1-7/8"). Therefore, the ARW can be used to quickly tighten/loosen any size of bolt without the addition of unique sockets or the risk of slipping off the bolt.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 (see picture). 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 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.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 top 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). 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).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.For more information, please see the following videos of the ARWDemo Video: https://youtu.be/AGQwjQE0-eMCAD Rendering: https://youtu.be/9UfNI25GShQ