Nuts&Bolt baby dexterity toy

thingiverse

Ever since becoming a parent, I wanted to create this nut and bolt toy for my child that fosters hand-eye coordination. At the time, I didn't have access to a 3D printer. Before long, my kid grew old enough to build our Prusa MK3S printer with minimal supervision and guidance from me. Now, I finally printed this toy, but it's too late for my child; however, he finds it to be a nice fidget toy. Spinning the nuts on the bolt is quite satisfying. My objectives for this project were: + Adhere to Consumer Product Safety Commission regulations [CFR 1501.4](https://www.govinfo.gov/content/pkg/CFR-2012-title16-vol2/pdf/CFR-2012-title16-vol2-sec1501-4.pdf) and associated guidance. + Incorporate large, rounded threads for a good tactile feel. + Minimize sharp edges. I also aimed to prove out my novel approach to generating screw threads - this was an engaging intellectual exercise, although I conclude that there are more effective ways to create threads in OpenSCAD. The source file employs the method I developed and documented on my blog. I struggled to eliminate all sharp edges in OpenSCAD. When cutting a thread into something, it will inevitably leave an edge somewhere. So, I added a small recessed eyelet on the bolt head with the intention of printing it with ABS and then exposing it to an acetone vapor bath to dull any edges. However, we no longer have any babies in the house, so there's no need, and the edges turned out not-sharp anyway. Additionally, the edges are primarily on the nuts, so they're not exposed when the nuts are on the bolt. This project represented some significant milestones for me: + This is the tallest object I've ever printed. + This is my longest continuous-run print; 14 hours at 0.15mm layer height. I've had more projects with more total print time, but they were split into separate print jobs. + This is my first time printing with ABS without an enclosure. It printed fine, but the odor was unpleasant.