Designing and fabricating 3D models is a great resource for teachers. The software is easy to use and 3D printers cost as little as a regular desktop laser printer. The plastic material used to fabricate 3D models is cheaper than a toner cartridge. Models can be designed and prepared for printing in one class period. Students use math, science, and art concepts when developing 3D models. All the models can be printed in the classroom.
3D printing was created to develop rapid prototypes. Prototypes are models of a finished product. The printed object itself is not the finished product. Printed objects are not durable enough for commercial use. But, they are durable enough to teach several concepts. Math and science models are two examples for content integration. Students can design and print historical models. They can print models of scenes in books. Music students can print their own instruments and art students can print sculptures.
Fused Deposition Modeling (FDM) or Fused Filament Fabrication are used to refer to the fabrication of models in 3D printers. The term Additive Manufacturing (AM) is also used to describe the process. A heated extruder deposits layers of melted plastic. The heated plastic bonds with previous layers to form the final model. Imagine using a hot glue gun to deposit layers of hot glue.
Printers use a variety of plastics in the fabrication process. These plastics include ABS, which is in a variety of items we use every day. Lego blocks are one example of an item made of ABS plastic. Printers also use biodegradable PLA plastic. Other plastics include Polycarbonate(PC), Polyamide (PA), and Polystyrene (PS). These plastics are not used as often. The plastic filament is in spools. Typical filament measures 1.75 millimeters in diameter and comes in spools in lengths of 250 meters.
Most 3D printers for non-commercial application will use either PLA or ABS plastic. Organic materials like cornstarch and sugar are used to create PLA plastic. Oil based materials are used to create ABS plastic. ABS has a higher melting point than PLA. Printing with ABS plastic requires a heated printing surface. This prevents the model from warping. When ABS melts it produces a bad smell and the room must be well ventilated. PLA plastic doesn't smell as bad. The smell of melting plastic can be unpleasant so keep the room well ventilated.
Creating 3D Models
Models are designed with special Computer-aided Design (CAD) software. There are ways to duplicate objects without using CAD software. Objects can be scanned using 3D scanners. Special software can create 3D models from digital camera images. The software converts pictures taken from lots of angles and creates a 3D model of the subject.
Design and scanning software use the STL format to save files. There are other formats but this format appears to be the standard. STL is an abbreviation for stereolithography. Before printing a model, a special piece of software called a "slicer" processes the file. The software, as the name suggests, slices the model into a series of thin layers used to print the model. This slicer software is part of the printer software. Printer software is available from the manufacturer website.
The print Process
Printing a model is time intensive. Models can take several hours to print. Complex models with high resolution settings can take days to print. We control the printed resolution with the printer software. The resolution of printed models depends on the thickness of the layered plastic. Thinner layers produce models with a higher resolution. Most printers are set to print models with a medium resolution. Printing a model with low resolution is faster but the models won’t be as sturdy or pleasing to look at.
The development of objects uses basic concepts in geometry. Some of these concepts include angles, cubes, spheres, triangles, and cones. Students use measurement concepts when using shapes. These concepts include length, width, height, perimeter, area, and volume. Models are a combination of merged and split shapes. This process allows us to develop complex models.
Students can construct a variety of science experiments. They can design and print simple machines like inclined planes, wheels, and pulleys. They can construct elaborate models using basic concepts learned by fabricating simple machines. Some elaborate models include screws, augers, cams, scissor lifts, and gears. Students can experiment with a variety of designs to determine why one version of a simple machine is better than another.
Modeling and printing historical events, cities, and buildings provide students and enriching experience. Class projects can include the reconstruction of historical buildings. Artifacts are an important part of history. Students can recreate historical artifacts like vases, jars, and masks. Students can design and print scenes in stories. These scenes can form the basis for a diorama.
Begin With Easy To Use Software
There is a variety of software used to develop 3D models. I prefer TinkerCAD for beginners. The software provides useful resources for teachers to manage student projects. Teachers can create and moderate accounts for students that are 12 and younger. Students can create basic projects in one class period. TinkerCAD is a web-based, so software installation is not required. TinkerCAD models are compatible with any 3D printer that supports the STL format.
Benefits for Students and Teachers
Models are not always created from one print. Parts of a complete model are often printed one at a time. Students can assemble the model with model glue or by snapping the pieces together. I have found that model glue for plastics works best. Model glue avoids the use of glues like Super Glue.
The design of complex models requires a great deal of higher order thinking. Students need to work in a collaborative environment when designing these models. Collaboration requires lots of communication and sharing of ideas. Apart from the design, students need to consider the time it takes to print the pieces of the complete model. Teachers can impose material limits which limit the size of the model.
The Lessons in this Issue
Digital Maestro Magazine March 15, 2018
We begin with a basic project that will become the cornerstone of future projects. The basic project introduces teachers and students to the TinkerCAD environment. We begin with a basic wheel and axle. The wheel and axle are simple machines with a variety of applications. These objects will be used to explore a variety of math and science concepts. Students will use radius, diameter, and circumference to design their wheel and axle. Students learn how gravity plays a role in the design and print process.
After designing the wheel and axle we will design a fun project. Students will design a toy top. This design builds on the skills used to design the wheel and axle. The toy top will help teach concepts of centrifugal force, gravity, and balance. It can help teach angular momentum with older students. Trigonometry will be used toward the end of the project.