How to Design for 3D Printing?

In this section, you will know about the best design practices, get recommendations on what software to use and learn tips for preparing those perfect design files.

The first step in 3D printing designs in the correct preparations of your digital files. If you are already familiar (or willing to get your hands dirty) with 3D design, just create a 3D printable model using your favourite CAD software and simply save your models in the STL file format (all modern CAD software packages can do this).

The STL Format (STL = stereolithography) An STL file is an industry-standard file format used by all 3D printers. It uses triangles to represent the outer and inner surfaces of a solid 3D object and describes a raw, unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.

How to convert Model to STL?

AutoCAD

Note: you can only export 3D solid objects to STL

1. At the command prompt type “FACETRES”
2. Set FACETRES to 10
3. Type “STLOUT”
4. Select the objects
5. Enter Y or hit Enter for Create a binary STL file? [Yes/No] 6. Enter Filename
7. Save

Autodesk 3DS MAX(3D Studio MAX)

1. File/Application Menu > Export
2. Select type StereoLitho *.stl
3. Enter Filename
4. Select Binary
5. Save
6. OK

Autodesk INVENTOR / Mechanical Desktop

You can export individual parts or whole assemblies.

1. Manage tab > Update panel > Rebuild All
2. File > Save as > Save Copy As
3. Select STL
4. Enter Filename
5. Select Options

1. Format > Binary
2. Units > mm or inches
3. Resolution > High
4. Save

Blender

1. File > Export > STL…
2. Enter Filename
3. Select location
4. Click button Export STL

Creo

1. Open the File pull-down menu and Save as then Save a Copy.
2. Change the Type option to Stereolithography (*.stl).
3. Type a filename and click on OK to close the dialogue. A new Export STL dialogue will open.
4. Change the Chord Height value X1 to 0 (zero).
5. Change the Angle Control value X2 to 1
6. On OK to close the dialogue and the STL file will be created in the working directory.
7. The display will change to show the faceted surface of the STL file. If it looks really faceted and you’ve nested a few files together you may need to break the file down and save them individually as Creo seems to have a maximum limit in files.

Pro Engineer

1. File > Save a Copy
2. Select type STL > OK
3. Select Coordinate System Standard
4. Check Binary
5. Set Chord Height to 0 (Pro/E changes it to the smallest allowable value)
6. Leave Angle Control at the default
7. Enter Filename > OK

Rhino

1. File > Export Selected or File > Save As
2. Select the objects to be exported
3. Select File Type Stereolithography (*.stl)
4. Enter Filename
5. Save
6. in STL Mesh Export Options, Enter Tolerance 0.02 mm (0.0008 inches), then click OK.
7. Select Binary
8. Uncheck Export Open Objects
9. OK

Solidworks

1. Click File, Save As.
2. Select STL (*.stl) for Save as type, then click Options.
3. Select output as – binary
4. On the ‘Resolution’ settings click Custom and set the deviation to 0.1mm and the angle to 5°.
5. Check the box ‘Save all components in a single file’ and then click OK.
6. Now enter a filename, click save and you’re all done!

Although 3D printing offers great design freedom, we need to remember that anything can be “drawn” in 3D on a digital canvas, but not everything can be 3D printed.

Top 3 things to look out for:

Overhangs & support:
3D printers cannot deposit material on thin air. Walls at an angle greater than 45° will require support, affecting the surface quality.

Level of detail:
The smallest feature a printer can create depends on the size of the end effector (nozzle or laser) it uses

Layer Height:
The layer height affects the vertical resolution of a part. It’s effects are visible are areas with greater curvature (it appears as stair-stepping).

Find a design online:

If you are new to design (or if you are simply looking for something to print fast), then one of the many online repositories might already have what you are looking for.

If 3D modelling sounds tough (or if you are simply short of time), explore the best online model repositories, and find what you are looking for amongst the existing designs.

Thingiverse: The largest online repository with thousands of free 3D printable files for desktop 3D printing.

MyMiniFactory: A popular online repository with free 3D models that are tested for quality and are guaranteed to be 3D printable.

Cults: An online marketplace with high quality 3D printable models by professional designers, and curated collections connected to big-name brands.

Pinshape: An online marketplace with both free and premium 3D printable files, focusing mainly on hobbyists.

GrabCAD: An online repository of many 3D models that also includes some 3D printable files, focusing mainly on engineering professionals.

How to choose material for 3D Printing?

A wide range of thermoplastic materials, suitable for both prototyping and some functional applications is available. Different 3D printing materials have different characteristics and properties. It is important to choose the right material to get the desired result.
Selecting the right material depends on various properties of the material like its tensile strength, flexibility, impact strength, temperature resistance, and also the colours available.

PLA (polylactic acid)

High stiffness, good detail, affordable. PLA is a biodegradable thermoplastic for low-cost, non-functional prototyping. Greater detail than ABS, but more brittle. Unsuitable for high temperatures.

Reasons to choose PLA

  • Good tensile strength
  • Good surface quality
  • Easy to work with at high print speeds
  • Allows the creation of high-resolution parts
  • Ideal for models and prototypes that require aesthetic detail
  • Great for lost casting methods to create metal parts
  • A wide range of colour options available
  • Combine it with PVA for interconnected prints

PLA+ (Polylactic acid)

PLA+ is a technical PLA (polylactic acid) material with toughness similar to ABS. Ideal for reliably printing functional prototypes and tooling at larger sizes, Tough PLA offers the same safe and easy use as regular PLA.

Reasons to choose PLA

  • Impact strength similar to ABS, greater than regular PLA
  • Higher stiffness compared with ABS
  • Less brittle than regular PLA
  • Withstands temperatures up to 60 ºC
  • Gives a more matte surface finish quality than our normal PLA
  • Suitable for post-processing with improved machinability compared to regular PLA
  • More reliable than ABS for larger prints, with no delamination or warping
  • Compatible with support materials (PVA and Breakaway) giving full geometric freedom when designing parts

PETG (Polyethylene terephthalate – glycol-modified)

A thermoplastic filament that combines the strength of ABS, some flexibility of Nylon and the easy printability of PLA. It is also very durable and temperature resistant. It is good for printing mechanical parts and protective components. It is also good for printing large objects since it doesn’t warp much.

Reasons to choose PETG

  • Durable
  • Good for mechanical parts and protective components
  • Doesn’t warp so good for printing large objects
  • Translucent in colour

ABS (acrylonitrile butadiene styrene)

Commodity plastic improved mechanical and thermal properties compared to PLA. ABS is a common thermoplastic with good mechanical properties and excellent impact strength, superior to PLA but with less defined details.

Reasons to choose ABS

  • Good mechanical properties
  • Good interlayer adhesion, especially when printing with an enclosed front
  • Withstands temperatures up to 85 ºC
  • Great for exceptionally strong prototypes or end-use parts
  • Achieve superior aesthetics compared to using other ABS filaments
  • Acetone dipped parts display ability to hold pneumatic pressure

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