3D Printing Workshop
Auteur: Tim Geers
Additive manufacturing introduction
Additive manufacturing is a manufacturing technique which relies on adding material instead of removing it. In contradiction to classical machining operations like milling, turning, cutting, drilling and so on. These classical operations all have in common that they remove material in order to get to a final product/part.
Like the name implies additive manufacturing adds material where it needs to be to get to a final product. instead of removing material where it is unwanted. There are many different additive manufacturing techniques. The most common is Fused Deposed Molding often referred to as 3D printing. FMD is by far the most common and widely available additive manufacturing technique and also the one used in this workshop.
FDM (3D Printing)
FMD is a additive manufacturing technique that can print plastic parts. It works by melting plastic and extruding it through a small nozzle. The nozzle lays down a thin layer of plastic on the bed of the 3D printer. Then the nozzle goes up a bit and lays another layer on top of the previous one. This finally results in the final part.
The plastic that is used is called filament. The filament basically is a really long wire of plastic that is rolled up on a spool. There are a few basic differences that sets different filaments apart.
There are a few different kinds of plastics that are available for FDM printers. The most commonly used materials are PLA, ABS and PETG.
Easy to print high quality
Low melting temperature
Parts can deform when exposed to higher temperatures (>60C)
Low mechanical strength
High mechanical strength
Parts don’t deform when exposed to higher temperatures
Hard to print high quality
Parts have the tendency to warp due to the plastic shrinking when cooling down
High mechanical strength
Parts don’t deform when exposed to higher temperatures
Hard to print high quality (Although better than ABS)
TPU (Flexibel material)
PVA (Water Soluble, Ideal as support material)
The diameter of the plastic wire on the filament spool can vary. There are two different diameters available 1,75mm and 2,85mm. The diameter filament you need to use depends on the 3D printer you have. Most of the printers now a days use the 1,75mm type.
There are two different types of 3D printers: Cartesian printers and Delta printers. Cartesian printers work pretty straight forward. Each axis has its own motor and is own lineare guidance. Controlling the movement is easy since each motor controls its own axis.
With a Delta printer things are a bit different. The print head is connected to the frame by rods that connect to three linear bearing that are connected to the frame posts. The movement of these three bearings controls the movement of the print head. If you only want the print head to move in the X axis all the motors have to work together.
Delta printers tend to have a better print quality and can print faster. Cartesian printers are easier to control and can have a direct drive extruder this means that you are able to print flexible filaments like TPU.
When working with FDM printers for the first time it is important to know the workflow. The process starts with a 3D model you want to print. Either draw it up in a CAD program or download it from a site like thingiverse.com. The CAD model needs to be a .STL file. Now this 3D model needs to be ‘sliced’ since FDM printers build up a print layer by layer the so called ‘slicer’ (Computer program) slices the 3D model into layers that the 3D printer can print. The slicer creates a G-code file, this is a file with instructions that the 3D printer can understands. The G-Code file tells the printer where to go and how much plastic it must extrude.
CAD → Slicer → 3D printer
(STL → GCODE → 3D Printer)
The slicer we are going to use is Cura. In Cura you can change all the print settings like layer height, print speed, infill percentage and so on. We first have to install Cura on our computer. After that we need to give Cura a little bit of information about our printer.
- Download Cura: https://ultimaker.com/en/products/ultimaker-cura-software
- Open Cura
- Go to Preferences → Printers → click “Add”
- Go to Other → Select “Delta Go”
- Give the printer a name and click “Add printer” (Name of the printer does not matter)
- Click “Machine settings”
- Use the following settings, leave start- and end G-code as is.
- Click Close
Slicer settings/Printer Profile
Cura now knows the physical size of the printer. This is important so that cura knows what 3D model can of can not be printed on this printer. There are hundreds of print settings you can change in cura and they all have to be set correctly in order to get a good print result. Luckily we have made a Cura settings profile which contains all the settings to get a perfect print result. You can download our profile here
- Go to Preferences → Profiles → click Import and chose the profiles you want to import. (the file you just downloaded) Once imported click close.
- Click “Custom” (Next to “Print Setup”)
- Click on the box next to “Profile:” it probably says something like: “Fine - 0.15mm”
- Select the profile you have just imported.
- Cura is now ready to use.
Cura should look something like this.
Using Cura Basics
The first thing we are going to print is a benchy. This is a small boat that tests your slicer and 3D printer. Let’s start by downloading the stl file.
- Go to: https://www.thingiverse.com/thing:763622
- Click: ‘DOWNLOAD ALL FILES’
- Unzip the file
- There should be a /3DBenchy-_The……./files/3DBenchy.stl
The next thing to do is to load the 3D model intro Cura.
- Drag and drop the 3DBenchy.stl file into cura
- Click: File → Open File(s)…
- Navigate to the 3DBenchy.stl file and click open
- Click: Save File
- Copy the file to the SD-Card
The model should appear in the center of the print bed.
Using Cura Advanced
The height of each layer in de print greatly determines the print quality. The lower the layer height the finer the print will look but the longer it will take to finish. Most of the time 0.2mm is used if you want a higher quality print you can change this setting under ‘quality’ from 0.2mm to 0.1mm or even 0.05mm. Keep in mind that changing this setting from 0.2mm to 0.1mm will roughly double the print time. Leave Initial layer height 0.3mm.
To save plastic and time most 3D printed parts/models are not massive but are filled with a certain pattern. The amount of space that is filled with plastic is the infill Density. The higher this percentage the longer the print takes and the stronger it gets. You can change the Infill Pattern to your liking
Sometimes a model is oriented so that some features of the model need to be printed in mid air. This is not possible and will make a mess of plastic. You always want to print on something. Either the print bed or a previous layer. If that is not possible you need support. This is a structure that cura will make on top of these structures can be printed. So that printing features with a big overhang can be printed. These support structures need to be removed after printing. On the next page you can see that parts of the space shuttle will be printed in mid air. After the Generate Support is turned on these parts are printed on top of the support.
Build plate adhesion
When printing long small parts there is a problem that the part does not adhere good enough to the print bed since there is not enough surface area. The part can fall over during printing, this will result in a mess of plastic wires and a failed part. This can be solved by printing the part on a raft like you see below. This raft makes for a bigger contact area with the print bed. Change Build Plate Adhesion Type from Skirt to Raft.
Before you can start a print you need to prepare your printer. We have made a list you can check before printing.
- Make sure the right filament color is loaded in the printer.
- Make sure there is enough filament on the spool to finish the print
- Make sure all axis can move freely
- Make sure the print bed is clean
- Make sure the Hot-end is clean
Starting a print job
Plug the SD-Card into the printer. Press the select button and scroll to ‘Print from SD’. Select the file you want to print. The printer should now headup the Hot-end and heated bed. While the hot-end is heating up filament may come out, clean this up using tweezers. Once the printer is heated it’s automatically going to home and start printing.
If you want to change filament or load new filament follow the next steps.
Heat up the hot-end to 200C. Click the selector on the printer and go to Control → Temperature → Nozzle: and change 0 to 200
Once the hot-end/nozzle has reached 200C you can pull out the filament by hand
Now insert the new filament and push it till the filament that comes out of the nozzle is the color of the new filament.