October, 18, 2023 by Andrew Farmer in 3D Printing
Several years ago, I undertook the creation of the Swarm Bot as a commissioned project destined for Trade Shows. While it initially served its purpose, the project left room for improvement, particularly in the areas of joint stability and design accuracy. In this blog post, I will outline the pragmatic evolution of the Swarm Bot, detailing challenges faced and the practical steps taken to refine its form.
Version 1 had its flaws, and a very obvious join in the middle.
Returning to the design years later, drawing on skills from my studies, hobbies, and past trials, I aimed to improve the design while staying true to the original specifications. The focus was on making the joints more robust.
The design specifications as given to me.
Designing 3D ball joints that maintain stability over time poses a unique set of challenges. Striking the right balance is crucial, as a joint slot too small risks breakage during the assembly process, while one that is too large results in a loose joint unable to support weight.
In my approach, I crafted a slot slightly undersized compared to the ball, integrating strategic slits for plastic flex. This design allows for a controlled level of flexibility, considering the limitations of printing in PLA rather than more elastic materials like TPU or Silicone. An additional consideration was the expansion of plastic under heat during the printing process, making precise measurements less than ideal.
To enhance the flexibility and adaptability of the ball joints, I made a strategic decision to incorporate slits into the ball itself. Additionally, I opted to hollow out the interior of the ball. While acknowledging that this approach inherently introduces a level of structural compromise, it serves a crucial purpose—allowing the ball to flex and fit snugly into tighter joints.
Version 4 retained this refined design but with added modularity for enhanced printing and assembly. The decision to maintain the hidden cuts, combined with a more modular structure, not only contributed to a cleaner and more visually pleasing appearance but also streamlined the manufacturing and assembly process.
In versions 3 and 4 of the Swarm Bot, the combination of PLA and transparent resin made assembly a breeze – no need for glue. Additionally, both versions feature built-in space for LED lights powered by a D battery pack inside.
The LED sits under the resin lens cap.
Following version 3, I revisited the design one last time to enhance modularity and address issues, particularly focusing on strengthening joints. The design of version 4 reflects the culmination of these efforts. The printed parts, seen here, are all set for seamless assembly.
An exploded design in Fusion360.
All parts for version 4 printed. Note the modular design.
Rendered version 4.
In concluding this journey of iterative design, from version 1 to the refined version 4, the Swarm Bot stands as a testament to the persistent pursuit of improvement. Perhaps in the future I can consider a version 5 that uses arduino motors to move.
