Spiral Pencil
I wanted to find a way to highlight the material layers generated by FDM 3D printing rather than simply enduring this characteristic. I believe this "flaw" can actually give real aesthetic value to an object, offering a look radically different from standard plastic injection processes, often synonymous with mass production.
The most obvious solution was to exaggerate the thickness and width of the layers to make them more visible, more massive, and fully embraced.
The Approach
The idea is to turn the technical constraint into a visual signature. However, pushing the machine to its limits requires some adjustments. After numerous tests, it turns out that to print in very thick layers (at least 1 mm thick) with a standard 0.4 mm nozzle, it is essential to maintain a ratio of approximately 2/5 between the layer height and width.
Indeed, this is the ratio that gave me the best part quality as it prevents the part from collapsing as the print progresses. Without this ratio, the gap between the part and the nozzle grows increasingly larger, resulting in unstable extrusion and "wavy" layers. Therefore, to print a part with 1 mm layer height, a minimum width of 2.5 mm must be imposed.
Printing small parts or fine details becomes very difficult at this width. To overcome this issue and stabilize the process, the technical solution ultimately turned out to be a hardware one: opting for a larger diameter nozzle. Currently for this type of printing, I use a 1.4 mm diameter nozzle. With it, I can print layers of 1 mm thickness with a width of 1.7 mm or slightly less without any collapse issues.
The Pencil
To print this pencil, I opted for layers of 1 mm thickness and 2 mm width. This ratio allows me to achieve an interesting pencil diameter for grip while using a BIC Cristal refill — affordable, easy to install, and pleasant to use.
The added bonus of this pencil is repurposing the thick layers as threads to hold the cap. Although the cap appears to be a simple cylinder, it is actually slightly conical. This shape allows the cap to be engaged over about 25 mm and then screwed onto the pencil body. This threading works on both ends of the pencil.
I also looked for an elegant way to have a solid clip on the cap while keeping the thick layer constraint. I opted for printing a loop flat, which I then thermoformed into its final shape using my hot air soldering iron.
Materials Used
- PLA Francofil Blue (RAL 5002)
- BIC Cristal refill
