MER Project

3D printer is a tool used to create 3D objects that have been designed on a computer. 3D printers have a wide range of shapes, sizes and types. They are computer-controlled machines. Similar to paper printers that lay down ink in one layer to create an image, 3D printers lay down material in multiple layers to create a 3D object.

Compared to other CNC tools, 3D printers are inexpensive. We can use them for fast and inexpensive manufacture of custom parts. Therefore are 3D printers one of best tools for manufacturing prototypes. Machines for manufacturing large series of products require precisely machined molds, which means more expenses. Using a 3D printer, a part can be cheaply designed and made, and then its design can be modified and reprinted. The procedure can be repeated until we are completely satisfied with a product.

HOW 3D PRINTER WORKS

To understand specifically how 3D printers work, and how to design models for them, we need to understand the different types of 3D printers. Although the materials and methods with which parts are created differ, all 3D printers construct parts by adding material layer by layer, fusing each layer together to make a solid object. There are a couple different types of 3D printing procedures. Some are more suited or larger series of products, others allow the usage of multiple materials and colors. Some types are very easily and cheap to build, because of the way they work.

^{Figure 1: An example of adding material in  FDM 3D printer}

FDM (Fused Deposition Modeling) is probably one of the most common types of 3D printing, and it is the easiest to understand. In this type of 3D printing, the material is melted down by the printer head, and extruded onto the heated surface - printer bed. The head of the printer lays down material layer by layer to build up a 3D model, during cooling layers are fused.

DESIGN MODEL FOR 3D PRINT

3D printers allow designers to go straight from concept ideas and design models to physical models. In order to do so, the object needs to be designed on a computer using 3D design software.

There are many different CAD (Computer Aided Design) programs to design 3D models for various purposes. Design programs to design 3D models for various purposes. Design programs like Tinkercad or Autodesk 123D are free and great for beginners interested in 3D design and 3D printing. Engineers to design parts and assemblies for production use programs like SolidWorks and Autodesk Inventor. DesignSpark Mechanical is also a powerful free 3D design tool.

^{Figure 2: Drawing a 3D model with DesignSpark Mechanical}

When designing for 3D printing, a few design guidelines and constraints should be followed. When designing, we should have in mind the printing process. All printers start building the part from the print bed, so it is very important to remember what face the part if being printed from.

Reducing print time and material consumption; by proper part orienting, you can reduce the amount of support material needed, which can minimize material consumption and print time. Support can be hard to remove and it creates a rough surface, which is not good. 

Model strength; on most desktop 3D printers, models usually tend to break along cross-sections of the model that are parallel to the 3D printer bed. Material is laid down or hardened layer by layer, and the layers may not fuse enough, creating seams along the cross-sections of the model. This means that along those planes model is less firm. If you know how and where force will be applied to your part, when orienting a model it is important to place a model in such way that direction of force is not along those cross-sectional planes.

^{Figure 3: Placement of the model on a 3D printer bed – preparation for printing}

Adhesion of the model to the 3D printer bed; on most printers, especially FDM machines, the 3D printed parts stick to the printer bed. If the contact area is small, it may cause that the model comes off the printer bed. Therefore, we must orient the model with the side that has the surface area on the printer bed.