3D Printing FDM (Fused Deposition Modelling)
v0.4 by Ger Walsh - Nov 2023
General
Video credits to UltiMaker.
Steps:
Preparing Digital Files
Here you have a number of options.
1. Design your own models:
To print, you need a 3D object in a file. These files may be: .STL, or .OBJ, or .AMF.
- Autodesk Tinkercad (In-Browser)
- onShape (In-Browser)
- FreeCAD
- Autodesk Fusion 360
- Rhino3D
- SketchUp (In-Browser)
- Solidworks
- Inventor (AutoDesk)
- Blender
- Z-brush, or SculptGL
Note: Sketchup can be used for free in the browser and is a good software for a beginner to start with. Sketchup Tutorials are available here. The only requirement for a 3D software is that it can produce a .STL file, so if you know another, it
* Slicing software will also be required, and is covered on the subsequent, relevant pages.
2. Download a 3D object:
There are many 3D files online, ready to download and print. The file type you need for printing is an .STL file.
- Printables, from Prusa
- Thingiverse
- Thangs
-
Some interesting, specific-purpose, repositories:
- ScanTheWorld
The Limerick City Model Project
3. 3D Scanning
"Structured Light" Scanning
Uses projected patterns, and a camera to map the distortion of these projections on a 3D surface. The resolution and quality of the projection, the kind of light (IR, etc.), refelctivity of surfaces and other factors can affect quality. Outdoor environments, or very large or small objects tend to be a challenge. Tends to be quite expensive.
image from bitfab.io
Photogrammetry
Convert a collection of 2D images into a 3D scan. Many phone apps available, but with limited resources and in-app paywalls, I don't have a recommendation yet. For PC, there are a few popular options, Agisoft Metashape ($179 for a standard license) or Meshroom (Alicevision - free), or Reality Capture (Epic Games - free for education use).
image from bitfab.io
Laser Scanning (LiDaR, Light Detection And Ranging)
Uses Time-Of-Flight or Trigonometry. Specialist Equipment.
image from bitfab.io
LiDAR features included with newer iPads and the iPhone 13 Pro.
CT, MRI, etc.
Medical use. Many technical variations.
4. Using Generative AI
Note. At the moment, I don't have much to add here. Gen. AI produces raster information, which is largely un-useful for 3D Printing. You can ask an LLM to generate .SVG files, or OpenSCAD files, but the results are probably no that useful either.
"Slicing" -ie., Assigning Materials And Properties
Slicing software takes your 3D model, slices it and creates .gcode, which you can then send to a 3D printer. Slicers are fairly easy to use. Material presets are probably already in the software/online. Or are available from the manufacturer. Settings needed for various printers are available with the software/online.
See the Getting Started section to get all the profiles you need in PrusaSlicer.
- PrusaSlicer (Free, tutorial)
- Ultimaker Cura (Free, tutorial)
- OrcaSlicer
- Simplify3D ($149 USD)
Fixing your .STL file
An .STL file needs to contain solid objects ("manifold", with no "naked edges"). Often the Slicer Program itself is able to fix minor issues.
Using CSG (Constructive Solid Geometry, eg., Boolean Union/Difference or Combine commands), helps keep models solid as you are working on them.
Netfabb, Meshmixer are tools that can automatically fix some issues.
In SketchUp, you can install a plugin called "SolidInspector2" to find problems and fix models.
Or the "_ShowEdges" command in Rhino is a very good way to highlight issues.
Materials And Properties
There are many plastics and bio-plastics that are suitable for FDM printing. This category is generally callled Thermoplastics, and some of the common types are PLA (Polylactic Acid), PET/PET-G, ABS, PS, TPU, and some mixed filaments that contain a kind of aggregate, in small particles that passes through the machine, e.g., metal filings, fine sawdust or filler made of coffee grounds, glass dust.
Almost all FDM printers use filament, i.e., rolls of long plastic strands. They are commonly available in 1.75 and 2.85mm.
We keep a good supply of PLA plastic. We can order more material as required, though we also welcome people bringing their own material. New materials are being developed regularly including metal composites.
The properties of FDM printing stem from material properties, extrusion process.
Layers - layer height, can be up to half of your nozzel diameter, determines most-directly the time taken to complete your print.
Infill - given as a '%', influences the time taken to print and the strength of the final part. You can define the pattern of infill to be generated also.
Also, Wall Thickness, Speed/Accel settings, temperatures for bed and nozzle, supports to be generated and lots, lots, lots more.
Test your printer with a Benchy (Benchmark Test), an XYZ cube or a Torture Test to see how well it is tuned.
Printing
Bed Preparation
The first layer of printing is very important. PLA is easiest to print. Use one of the Isopropyl Alcohol (Isopropynol, IPA) wipes to clean the bed. For other plastics, such as ABS, textured beds help with first layer adhesion. Techniques, such as Pritt Stick, glue or tape shouldn't be used on the PEI beds.
When you insert the USB stick, it will automatically prompt you with the newest GCode file. If not, use the button to select the Print menu and find your file there.
The next screen shows a few details about the print. Press the button again to start. The startup routine involves zeroing, mapping the bed, getting to the target temperature, and a cleaning routine for the nozzle.
On the Prusa printers, you can go to Tune > Live Adjust Z-Height to make fine adjustments (0.00x mm) during the print. You can also adjust temperatures, speed and material flow here.
Changing Materials
On the Prusa Mk4 or Prusa Mini's, go to Filament > Unload and follow the screen prompts. You will have to select the correct material in order for the machine to heat up and release the previous material, which may take a minute or two.
When loading material, use a cutters, to taper the tip of the material to make it easier to load. On the Mini, feed the material into the Bowden tube, and press Continue, and continue to push the material. The material will hopefully start to pull into the machine, will be forwarded to the hot end.
On the Mk4's the material goes into the top of the hot end and there is a filament sensor. Pressing "Continue" starts pulling the material in and pushes it through the extruder to purge.
The printer will continue to pass the material through the extruder, purging the last of the previous material. Select No on screen to purge a little bit more, if you think it might need to get a bit more out.
If the material isn't coming through at this point, the machine may be clogged. Try these steps again, and ask for help if it doesn't work the second time.