Fused Filament Fabrication (FFF) is an additive manufacturing process that builds objects by depositing continuous filament or thermoplastic materials.
Parts printed with the FFF technology are very rigid, which makes them great choices for projects with a rigidity requirement, such as jigs and fixtures, manufacturing aids, and functional production parts.
There are several key elements to consider when preparing 3D models for FFF printing. In this blog post, we are going to share our top 4 tips.
1. Understanding the Minimum Feature Size
When preparing a part with intricate features and tight tolerances, make sure the minimum feature size, extrusion width, and extruder diameter are configured correctly.
For example, when slicing models with software such as the Simplify3D , standard toolpaths are generated as a complete loop. This results in a minimum feature size of about twice the width of extrusion. Small details may not be represented fully in the slice due to the limitations of FFF technology.
The example below displays a hollow cylinder with varying wall thicknesses. A standard .6 mm nozzle will easily print the thicker wall on the left, but is too large to recreate the finer details on the right.
2. Add Clearance for Inserts or Interlocking Parts
Incorporating non-printed elements, such as fasteners, electronics, switches, sensors, or even metal substructures into a 3D printed part expands the spectrum of usability—resulting in fully functional models and prototypes. 3D Printing with inserts is a key advantage for using FFF 3D printing, as inserts are not practical with SLA, SLS, or Polyjet. Thanks to 3DP Workbench’s open platform, users are able to access the 3D print to add non-printed elements during mid-print, and complete 3D prints without the need to tap drill holes for inserted objects.
When designing for models that include spaces for inserts, adding proper clearance is crucial. Add .25 mm clearance and a 2-degree draft angle for easy insertion. For interlocking parts (like a puzzle) use up to .4 mm clearance between mating surfaces to ensure they will fit properly.
For example, the outside diameter (OD) of an M5 nut is 8.00 mm max, therefore the nut pocket will be sized to 8.20 mm. However, keep in mind that only testing will ensure results for varying materials and processes.
The example below shows how to dimension a cavity for a M5 nut. The outer dimension (OD) of an M5 nut is 8.00 mm max, so the nut pocket is sized to 8.20 mm. Only real-world testing will ensure results for varying materials and processes.
3. Fine-Tune the STL Export Options
CAD packages have varying degrees of control over STL export detail. Solidworks gives the controls shown below. Export your STL files with a high resolution to ensure a quality print. See the comparison below between low and high-quality export options.
The example below shows the differences between low and high-resolution STL export settings. A low-resolution input file may result in visible segmentation in the final printed part.
Most 3D printing software automatically places support structures based on the parameters that are set by the designer. If the print requires more attention, you may also manually add and remove support structures. Just remember: instead of horizontal overhangs, use 45-degree angles or arched geometry when possible to eliminate support structures and increase the strength of the final part. Watch the video to learn more about the support structure 45-degree rule.
The example below shows two flanged parts with overhangs. The one on the left has no bevel, and requires excessive support. The part on the right has been modified with a 45-degree bevel up to the overhang, which removes the need for support. In many cases it is also possible to change the orientation of a print to eliminate support structures.