3D Printed Modular Doll

Recently when looking at Public Domain Review's website, I became very inspired by these engravings from 1624 by Giovanni Battista Bracelli, a Florentine artist. The images were digitized and made available to the public by the Library of Congress.

The images show studies of people interacting. The people are made modular and are composed of various different parts.

I knew this was a perfect job for my 3D printer.

I've only designed a body, legs, and one head, but I intend to continue developing this modular person so that diverse human forms can be made. I also intend to paint them in different colors.

Two strategies really helped in this design.

1. User Parameters
   
   User Parameters enable users of Autodesk Fusion 360 to take full advantage of parametric design. It's difficult to overstate how much easier this makes everything until you've made a modular part that has to fit together. Because of this feature, it was trivial to make adjustments across my design and reprint. It also enabled me to continue designing while my print was being printed.
   
2. Chamfered Supports
   
   To support my learning on this assignment, I completed the Lynda.com/LinkedIn Learning course Fusion 360 Essential Training. In this course, the instructor compares the difference in tensile strength between 3d printed parts with chamfered supports, fillet supports, and no support. He suggests using chamfered supports on all 3d printed parts so that there are no right angles. I had never thought of this before, but it did enable me to think more freely about my design without worrying about parts that would break off accidentally.

My exploration of body parts is really only a first step and a proof of concept. I would love to continue working on this idea and explore more forms inspired by the engravings of Giovanni Battista Bracelli, but first I had to just make sure my joints and sockets actually worked.

My first attempt was not successful, but did give me hope for the idea. It also helped me to understand the tolerances that I was looking for when thinking about my FDM 3D printer and 1.75 mm PLA (an Ender 3 Pro).

The joints are a ball and socket concept. I created a pipe around the edge of my socket to make the opening slightly thicker so that I could pop the sockets in and out. The ball and socket concept enables some range of motion that is reminiscent of a joint in human physiology.

I printed two bodies with all of the necessary parts to attach to one another.

It turned out 0.5 mm of space was actually too much so I went back in and adjusted my user parameters to tighten the tolerance to 0.3 mm and the print is currently printing.

My body parts are currently printing and should be ready soon. I'll be sure to post an update once I have the fully assembled modular doll printed.

I'm still having issues with bed adhesion with PLA on my Ender 3 Pro, in spite of leveling the bed and playing with the heat level, so the next time around I'm going to try a cold pull from the nozzle and confirm that it's not clogged. I'm also going to start cleaning my bed with isopropyl alcohol before every print. These were some ideas I got from the Prusa forum.

The parts work. The range of motion is not very large, but I think this can be tweaked with some further adjustment.

For now I'm very happy with the result and plan on continuing to design/print parts.