Swivelling Console Arm              

                               This design was born from a request for a console arm which allowed users to perform yoga exercises next to a rowing machine. The console was to replace a fully fixed arm on one of Hydrow’s Rower’s (original arm shown below)
                                               

Iterations
I made two 3D models in CAD and ordered them for 3D printing. The first, shown below, swiveled from its base about an M20 bolt with two bushings. Ultimately this design required excessive bolstering given the long lever arm from the swivel joint to the console. FEA showed that this design may be difficult to make strong enough for the application

                                                                     


The second model makes significant simplification to the design. This model allowed only 90 degrees of rotation in either direction but requires many fewer parts and less complexity to ensure structural integrity. The primary issue with this design was feedback that the design may not pass regulatory testing (with TUV) for UL certification, due to a pinch point issue that stopped a prior design (see image below at right “pinch point”).

                             


To achieve 180 degrees of rotation in either direction, and also eliminate the risk of a pinch point from TUV’s perspective, I devised a third concept which we referred to as “Frank.” This version was accepted very positively by my manager and upper management, so we made next steps to refine the design for production. Below are some images and further description of the design. 

                                                                                                             

                                                                               



“Frank” Swivelling MechanismI first devised a layout for the swiveling joint. To minimize cost and keep the design close to an existing design which we knew held the console weight over years in the field, I chose a two-part pivot design which uses 3mm thickness POM bushings. (see image below)

                                                                                                   

The swiveling unit has two pivots, each comprised of a M8 bolt, nylock nut, a spacer to prevent unwanted deformation under compression, and 2x POM bushings to isolate motion. 

At the prototyping stage, the swiveling mechanism was made from 3D printed nylon. However, the parts were designed to be manufacturable from bent aluminum sheet metal. 

Main Arm SectionFor the main arm section, I had a few design goals:
  1.    Allow 180 degree swiveling of the console
  2.   Allow 10 degrees of downward monitor tilt in the backwards orientation
  3.   Manufacturable by casting
  4.   Blend with the industrial design gesture of the rowing machine
  5.   Manage console power/data cables
  
With these goals in mind, I took to solidworks. I started with: a flat platform with an M8 clearance hole in the middle (crosshatched right-hand below image), and the two mating holes which have to match geometry in the rowing machine of interest (at bottom of right-hand image, below). 

I projected 4 curves on to two parallel planes to form the general outline of the part. I made boundary surfaces from these projected curves, and knit these surfaces into a solid block. I made 3 iterations of the arm shape for presentation to my team. My aesthetic goal was to achieve a relatively hard, modern shape, with an infused organic softness. I was inspired by stone monoliths. 

                                       

When my team approved of the design concept, I added 4 more projected curves, projected on to two new planes, to form the inner walls of the part (these curves were used to essentially “shell” the part in a precise way). I added ribbing to the model, as well as clearances and bosses for cable guide clips (see image below), and ordered a 3d printed version, which I spray painted for a color match. 

                               


Top Cover Upper management recommended to add a cover over the swivel joint parts. Our CEO found an outside designer who conceived of the external surface shape for this top cover, shown in the image below. 

                                                                                                         

I took this shape and re-modelled it using boundary surfaces driven by equation-defined sketches, so I could easily modify wall-thicknesses during review cycles with our CM. I also implemented a snap feature on the inside of the cover, so that the cover snap fit over a standoff/spacer in the swiveling mechanism. 


Final Design / ToolingI sourced a final 3D printed model for review (shown below), and sent the CAD database to our CM. The CM made some feedback on a draft angle which they wanted to increase, which required moving of some of my projected curves. But after this change our CM approved the design and our management approved fabrication of a tool.


     



For excess inventory reasons, this design was never implemented to production.