3D Printing Overview and Tips

Intro

So, you want to learn how to 3D print? This article should give you a good idea of the basic theory and mechanics behind 3D printing or additive manufacturing, as its called in professional circles. It will also provide you with some tips and resources to help you create your first successful 3D print.

The What

3D printing is a relatively new way to create physical 3D objects from digital models. Before 3D printing became popular and accessible, objects were often created using molds or subtractive manufacturing. With the advent of cheaper electronics and parts, 3D printing has become an important tool for prototyping both in professional fields and with hobbyists.

3D Printing Methods

• Fused Filament Fabrication
  • The most common type of 3D printing that uses a heated extruder to feed filament onto a build plate
• Light Polymerized
  • Uses light to harden a photopolymer layer by layer
• Powder Bed
  • Uses lasers, heat or electron beams to hardened powdered materials layer by layer
• Laminated
  • Cuts cross sections out of a thin material such as paper, metal foil or plastic film and adheres them together layer by layer

As you can see the key phrase with 3D printing is layer by layer, this is the principle that makes additive manufacturing unique. Rather than starting with a block of material and cutting it away to reveal the final shape, 3D printing creates a shape by adding raw materials until the shape is created. This can result in faster manufacturing times and less waste.

The Why

Rapid prototyping is one of the biggest benefits of 3D printing. In industry, the advent of reliable 3D manufacturing techniques has allowed engineers and designers to speed up their product development timelines. Digital designs can be created in the morning and tested in the afternoon. For hobbyists, it can be argued that 3D printing has been even more beneficial. Now that 3D printing technology is cheap and readily available any maker can quickly design a housing or part for their projects in no time at all. They no longer need access to wood and metal working tools, in a couple of hours a design can be printed right on their desktop.

The How

For the rest of this article, the focus will be 3D printing using the fused filament fabrication (FFF) method. All of the printers here at __Space.URI use this method. As stated earlier, FFF utilizes a heated extruder to feed filament onto a build plate creating a 3D model layer by layer. To move the extruder, and sometimes the build plate, a 3D printer utilizes 3 stepper motors. Each motor is responsible for movement in one plane, these planes are the x y and z planes. There is also another stepper motor in the extruder that pushes filament through the heated nozzle. The printer reads .gcode files to determine how the extruder should move throughout the print. When you create a 3D model for 3D printing the models are usually output as .stl or .obj files. Your printer won't know how to read these files, that is where the slicing software comes in. Examples of slicing software include but are not limited to Cura, Makerbot, and Simplify 3D. The slicing software converts your .stl or .obj file into a .gcode file, which can be interpreted by the printer.

The Tips

At the makerspace we provide design software, slicing software, printers, and filament for all your 3D design needs. Important things to remember when printing are:

1. The printer can not print on air, and any overhangs need to have supports turned on.
2. The settings used for one print may not be great for another print. Use smaller test prints to see what sort of optimal settings you need.
3. Interlocking and Moving parts. These values will vary from printer to printer. Design small test printers before printing your final design.
   1. Interlocking parts should have a total space between them of ~0.25mm. For example, a peg in a hole that does not move should be designed so the diameter of the hole is 0.25mm larger than the diameter of the peg.
   2. Moving parts should have a total space between them of ~0.5mm. For example, a peg in a hole that moves freely should be designed so the diameter of the hole is 0.5mm larger than the diameter of the peg.
4. Test prints are your friend. Scale your model down and/or print with low infill to see where your errors will arise before moving on to that final print.