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Key design considerations for 3D printing

A list of things to keep in mind when designing a model for 3D printing - regardless of the technology that you will be printing with.

Written by Robin Brockotter

Key design considerations for 3D Printing

Introduction

Different 3D printing processes have different capabilities and different design restrictions. In this article we will talk about key design considerations that apply to all 3D printing processes. For process specific guidelines click here.

We will assume you already have some knowledge about 3D designing and modeling. The specific design software you use to create your 3D model does not matter. If you are completely new to 3D modeling, there are many excellent software to introduce beginners to 3D design that also offer a strong line of video tutorials to help you understand the basics.

Keep this infographic near you while designing and use it as a quick reference:

3D Printing Design Rules
Click here to download the <i>3D Printing Design Rules poster</i> in high resolution for <em>free</em>

Digital vs. Physical

The most important thing to remember while designing for 3D printing is the fact that your digital design will become a physical object. In the digital design environment, there are no laws of physics to adhere to, such as gravity.

Anything can be "drawn" in 3D on a digital canvas, but not everything can be 3D printed.

Each 3D printing process has its own limitations. Here are the most important design considerations that apply to all of them that you should keep in mind:

General Design Consideration for 3D Printing

Overhangs

All 3D printing processes build parts layer-by-layer. Material cannot be deposited onto thin air, so every layer must be printed over some underline material

Overhangs are areas of a model that are either partially supported by the layer below or not supported at all. There is a limit on the angle every printer can produce without the need of support material. For example, for FDM and SLA this angle is approximately 45o degrees.

It is a good practice to limit the overhangs of a model, as layers printed over support usually have a rougher surface finish.

Image showing the effect of increasing angle on overhang quality for FDM printing

Wall thickness

The second thing to keep in mind when designing a part to be 3D printed is wall thickness. Every 3D printing process can produce accurately features that are thin up to a certain point.

For example, imagine you are an engineer who designs hang gliders for a living. You have come up with a great, new design that you have decided to 3D print scaled down for testing. 3D modeling programs allow you to model the sailcloth of the wing, but you would encounter problems when you would try to 3D print it, as its thickness would be extremely small.

As a good practice, always add thickness to your models. Walls with thickness greater than 0.8 mm can be printed successfully with all processes.

Warping

Something that is often easily overlooked while designing a 3D model is the fact that the materials used for 3D printing undertake physical change: they are melted, sintered or scanned with a laser and solidified. The heating and cooling of material can cause the parts to warp while printing.

Large, flat surfaces can be especially prone to warping. Warping can typically be avoided by using correct machine calibration and having adequate surface adhesion between your part and the print bed. Your Hub will be able to offer more advice on design techniques that can be used to minimize the likelihood of warping.

A good practice is to avoid large flat surfaces and add rounded corners to your 3D models.

Black ABS in 200 micron showing warping of the bottom left corner</a>.

Level of detail

When you are creating a 3D model with intricate details, it is important to keep in mind what is the minimum feature size each 3D printing process can produce. The minimum level of detail is connected to the capabilities and mechanics of each 3D printing process and to the selected layer height.

The process and materials used will have an impact on the speed and cost of your print, so determining whether smaller details are critical to your model is an important design decision.

Marvin printed in 200 microns FDM, 100 microns FDM, SLA and Material Jetting (from left to right)

Rules of Thumb

  • Avoid overhangs in your design when possible, by using angles smaller than 45o.
  • Add at least 0.8 mm wall thickness to your models.
  • Avoid large flat surfaces and use rounded corners to avoid warping.
  • Decide what is the minimum level of detail your models require and choose a 3D printing process accordingly.
Process Specific Guidelines

Are you designing with a specific 3D printing process in mind? Follow the links below to read the full guidelines for each of them:

Or download the poster that summarises all key design considerations that we prepared for you:

3D Printing design rules poster

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