[G-03] Geoscience education from elementary school to university students

[G03-P02] School seismographs made with 3D printed parts

*Yoshio Okamoto¹ (1.Kamnoetvidya Science Academy, Thailand)

Keywords:seismograph classroom 3D printer, Arduino

We have been developing a school-use seismograph system for two decades (eg.Okamoto,1991). Recently this system has been improved employing a microcontroller Arduino and cheap super strong magnets of Neodium (Okamoto,2015,2018). However, the bodies and pendulums are made from aluminum plates and angles, so it needs metal crafting skills, and is also hard to get the materials. On the other hand, to motivate students to make seismographs, we developed more easy-making sensors using dairy materials (Okamoto,2015,2016). Due to its unstable structure, it is suitable for classroom demonstration but not appropriate for practical observation. In this regard, we developed an alternative version of the previous metal models employing 3D printed parts. The basic concepts are 1) Swing Gate(Paschwitz) suspension for the horizontal pendulum and 2) Kirnos suspension for the vertical pendulum. The free period of the pendulums is adjusted around five seconds for detecting both local and foreign earthquakes. This relies on the JMA 59-type seismographs. The advantage of the 3D printed parts are 1) cheap cost, easy and fast to make structures, 2) The STL files are distributable on our website, so anyone can make the system quickly and cost-less. 3) Complicated structure of the pendulum, such as a cross-spring pivot using two thin spring plates, is easily made with our 3D printed parts like a plastic hobby model construction. Also, we try to use dairy parts from the DIY store or Net shops. The present problems are 1) mechanical strength and durability of PLA materials compared with aluminum metal 2) Some parts, brass mass, signal-generating coils, and the primary coil spring for vertical pendulum still require special access or skillful hand-made. We get a kind of spring factory for the coil spring, where they can make a so-called "zero-length spring," using a cheap iron wire. As a result, we accomplish a long free period, having 5 seconds or more for the vertical pendulum. We will present our current situation at this conference and discuss the future developments to clear the present problems.