Cisco Room Kit Mini Legs

Background

The UVA hospital purchased a set of Cisco Room Kit Minis to create a no contact patient/clinician communication pathway for COVID-19 patients. Cisco intended for these webcams to be mounted to a television in a conference room, so the hospital was at a loss when they wanted to set the cameras on flat surfaces in their hospital rooms. There are a couple of versions on Thingiverse, but one version is too unstable for the hospital environment and the other is expensive to print because it requires a large volume of support material. The hospital had dozens of these cameras in delivery, so a custom solution was needed as quickly as possible.

Design

Concept

The first goal of this design was to minimize production cost. UVA’s COVID Engineering Response team had access to a fleet of consumer-level fused filament fabrication (FFF) machines as well as an OMAX waterjet cutting machine. Considerations for optimizing each of these production methods are fairly similar: A flat design without starts-and-stops, for through-holes for instance, makes for a quick and easy-to-produce part. Continuous boundary parts without through-holes minimizes non-cutting or non-printing machine move times as well as boundary length. In FFF, boundaries are printed more slowly than infill material, so through holes increase boundary length and thus printing time. They can reduce the amount of material used, but oftentimes the savings are small when using a sparse infill. In waterjet cutting, through-holes must begin with a pierce operation which adds to cycle time in addition to the time to traverse to the desired hole location.

Using a basic engineering print that only provided for the external envelope dimensions of the device, I was able to recreate the Cisco Room Kit Mini in CAD without access to the physical device.

The next consideration was how to interface with the device. The camera has a feature located on the bottom of the device for connecting to the various display mounts that are available from Cisco, but utilizing this feature would add complexity to the part because it requires overhangs that are challenging for 3D printing and impossible for waterjet cutting. Instead, I chose to grip the entire body of the device. I could create a simple and flat “leg” that would constrain the device and simply slide onto the device from the side. The symmetric and rectangular shape of the device made it well suited for this pathway.

Execution

With my design principles in mind, I could begin modeling the legs. Unfortunately, I didn’t have access to the device because they had yet to arrive at the hospital, but I was provided with this external dimensions print. At first glance this print had little useful information; however, it actually has just enough. I took screen captures of each drawing view with an external dimension, and then pasted those onto their corresponding view planes in a CAD model. I could then use the provided dimensions to scale the images to actual size. With a front, top, and side view in place and correctly sized based on the reference dimensions, I could trace the provided boundary and then extrude that sketch as a surface. Then, I used the intersection of these three extruded surfaces to trim each surface and achieve an approximate 3D model of the camera. I didn’t need any more detail in my model because I chose to forgo using the onboard mounts, so I quickly sketched up a leg concept. Within two hours from start to finish, I was ready to create my first test print.

Production

I had the UVA Li Lab’s Maker’s Tool Works MendelMax3 3D printer and recycled PETG filament from GreenGate3D on hand for printing face shields, so I could immediately 3D print a leg kit for the hospital to try. It took a couple of attempts to get a part that I felt was robust enough to share, less than 20% infill paired with 0.3mm layers from a 0.4mm nozzle leaves the upper bend vulnerable to cracking, but within a couple more hours I had a test set ready for the hospital. Another member of the UVA COVID Engineering Response Team delivered my parts to the hospital, and a day later we had confirmation that these would meet their needs. The team rapidly produced almost forty kits for our hospital in just two days!

Conclusion

Armed with only a basic overall dimension print, I was able to go from problem to prototype in under four hours. Leveraging the power of CAD, I was able to create a reference model with sufficient accuracy to produce a test part that worked as desired the first time. I’m glad to have played a small role in equipping my local healthcare community with the equipment they needed to fight the COVID-19 pandemic and keep their members as safe as possible. After publishing this design on Twitter, I received a request to produce more for an IT professional that distributes these cameras, so I created a listing on Tindie to offer these to anyone who is interested in purchasing a kit for their own Cisco Room Kit Mini. I recently acquired a Creality Ender 5 Pro, so I can print them myself!