3D Printing 101
Link to class presentation: https://drive.google.com/file/d/1BnHxZkFcItljWIEBrO4h6kXHp5J7ttuD/view?usp=sharing
How does 3D printing work?
3D printing works by printing thin sheets of a model, and building them on top of each other.
What can we do with 3D printing?
Makes things with an aesthetic Purpose (movie props, children’s toys, etc.) We’re not worried about dimensional accuracy. Dimensional accuracy is how close the object comes out of the 3D Printer compared to the design in the computer.
Make things with an engineering purpose (motors, etc.) For these products, we need a high level of dimensional accuracy, as there are a lot of parts that need to fit into each other.
There are more material selections in engineering applications. These include materials that require electrical connectivity or magnetized parts.
Make things with a medical purpose (prosthetics, etc.) It’s a customized process for each piece that is made. Dimensional accuracy is important, but not as important and engineering applications.
Different Types of 3D Printers
DMLS – Direct Metal Laser Sintering
Only process capable of printing metal
Uses a laser to melt together fine particles of metal, nylon, and other similar powdered materials.
It is done by firing a laser at the powdered bed to melt the power in the shape of the model’s cross section. Once that layer is done, it will lower the bed for the next cross section, brush more material over the completed area, and repeat the process.
This method of printing is typically good for making jewelry and fine parts.
Tends to have a higher level of finishing as it generates less noticeable lines.
SLS - Select Laser Sintering
Similar process to DMLS but using sandstone or powdered Nylon material
There is a varied SLS method called Binding or Inkjet where it is also bonded/infused with coloured resin or ink
Capable of printing coloured models with photographic imagery
Very similar to the Laser Sintering method, except it uses resin instead of powdered materials.
Limited to the resin/polymer material however so while you won’t get weak products, they won’t be quite that strong either. Just like regular plastic.
Products will also have to be cleaned off and cured with UV lighting.
Operates like an Inkjet printer but instead of ink, it deposits droplets of coloured plastics
There is also a wider range of materials available such as heat resistant materials, soft/flexible rubber
FDM or FFF – Fused Deposition Modeling/Fused Filament Fabrication
Most common and easily accessible form of 3D printing.
Our machine uses 1.75mm filament, and has a 0.4mm nozzle
They mainly use plastic filaments commonly composed of PLA or ABS plastic.
Filament is fed through a heated extruder and print in layers.
Other FFF printers can also work with other filaments such as wood polymer or nylon. There are even foodsafe filaments.
Anatomy of a Typical FDM/FFF Printer
Stepper Motor
Different from conventional motors. They are found in all CNC devices. They control the gantry which allows for precise movement and positioning.
Problems can happen when you exceed the torque limit of the motor by moving too fast, or if the assembly runs into the gantry rails.
If you do not set the correct speed for your file, or if the gantry has been tampered with, it can ‘skip a step’ and cause layer shifting. Layer shifting is when the layers no longer align with the one below it, and starts creating a stair-stepping look to your model.
Gantry
Moves along on the x and y axis to control the position of the extruder assembly
Extruder assembly
What the filament feeds into and is printed from.
An internal motor will grab the filament from the cold/room-temp end, melt it, and then extrude it from the bottom.
As the plastic is going through a constrained tube, there is a risk of the plastic jamming up.
If the extruder is jammed, the fan won’t cool properly and the filament will not feed smoothly.
The heated build plate (a.k.a. Bed)
The bed where your printed model will be built off of. It will lower itself as each layer is produced.
It is heated to limit the amount of thermal contraction on the 3D printed part.
When you print, the bottom of your print starts to cool off but you’re constantly dumping more hot material. This can lead to warping if the print has two drastically different temperatures.
The bed needs to be levelled to ensure that the model is printed properly otherwise risk it coming out uneven/slanted/not sticking at all
Filament Materials for FFF Printing:
PLA
PLA is an easier material to work with.
Prints at a lower temperature.
It’s biodegradable.
Has a higher strength but it is more rigid.
ABS
ABS is petroleum based.
Has to be printed at a higher temperature.
Warps easier.
Needs a heated build plate.
Smells bad.
FILE TYPES
.stl = “stereolithography”; gives thin slices that can be printed in layers; only geometry, no colour. Ideal for Makerbot printers.
.ply = produced by many 3D scanners; may be read by ZPrint (colorjet powder printer), but can be unreliable
.obj = similar to .stl but have colour (texture) files as well, to give a colour print. Use with ZPrint
.wrl = produced by NextEngine, works well in ZPrint
.GCODE = output necessary for Ender printers.
Generating 3D Models
Computer Generated
Blender - https://www.blender.org/
TinkerCad - https://www.tinkercad.com/
Free CAD - https://www.freecadweb.org/
Fusion 360 - https://www.autodesk.ca/en/products/fusion-360/overview
Sketchup - https://www.sketchup.com/
Scanning
Scanning applications are now more readily available. You can even download them as phone/tablet applications. You would need a newer model of smartphones and tablets however, those with excellent camera lenses.
Otherwise you can purchase actual scanners that can be plugged into your computers/laptops for use.
Designing for 3D printing
There are a variety of different softwares that can be used to generate 3D models. Some free software includes Blender, Tinkercad, Free CAD, Fusion 360. We offer a class in Fusion 360 once a month.
Overhangs
Be mindful of overhangs. Overhangs are angles that aren’t supported by the previous layer)
Your next layer always has to be supported by the previous layer.
The filament doesn’t cool down instantly, and if the next layer doesn’t have enough support, it will droop and fall.
Stick to overhangs that are under 45 degrees.
You can also add support materials. Support materials are designed to support overhangs and are to be removed afterwards.
The program will input the support pillars for you, if the overhang is above 45 degrees.
Bridging
This happens when two endpoints need to connect to each other and there is no support in between.
The 3D printer essentially creates a bridge by tacking a single filament and dragging it across.
You need two contact points for the 3D printer to stretch the filament across.
Workspace Layout
Desktop
Communal use
Can be used to prep files
Ender 3
Produced by Creality, our current model is the Ender V3
Can insert a memory card directly
Filament Stock
Our stock of filaments for the printers
Ultimaker Cura
While you will design your files in a 3D modeling program, to generate the code for printers to operate, you will need a 3D printing software. Ultimaker Cura is free to download on Mac/Win/Lin devices, and works with a multitude of printers.
You can download it from here: https://ultimaker.com/software/ultimaker-cura/
Once downloaded, you will need to do initial setup.
When prompted to create an account, just Skip. You don't need an account to use the software.
Add a non-Ultimaker printer.
Add a non-network printer.
We have two Creality Ender V3 printers.
Do not adjust any of the settings, just proceed and complete the setup.
Start by Importing your Model
Position/rotate your model as needed
Scale the model down to size - You will need to scale your model down to size in order to fit and ensure it won’t take too long to print in class. The larger the model, the longer it takes to print
Slice the model to generate the 2d cross-sections, as well as get an estimate on time and material usage
Preview the print process
Adjust your print settings
You can just stick with the defaults that show up, or fiddle with only the recommended settings, but you can adjust the advanced settings if you need to modify your print further.
Resolution
Set to 0.1 to 0.25 mm.
The lower the amount, the higher the quality.
The lower the amount however, the longer it will take to print.
Infill
This is the inside of the print.
Infill varies, and determines how filled your part is.
The more infill, the stronger your piece, but it also takes longer.
15% infill is fairly strong. Standard is usually 10% to 20%.
Supports
If this box is checked, supports will be automatically added where the overhang is above 45 degrees.
Adhesion
If this box is checked, it will add a raft or brim to the bottom of your model for additional adhesion support. Recommended for small models (anything smaller than a 3cm diameter base)
Temperature Settings
This varies depending on the material you are using. When possible, use the recommended temp settings as printed on your filament's label.
ABS
Temp 230 to 245 celsius.
Temp is determined by what you’re doing. Higher temperature, parts are stronger because they are better fused together, but you can’t do as much overhang. If you want objects that look better and the strength doesn’t matter, set them to a lower temperature.
Bed temperature should be about 110 degrees to prevent warping.
PLA
Temp 190 – 215 celcius.
If the temperature is too high, the plastic could vaporize, and it could even carbonize, burn, and clog up the nozzle.
Bed temperature should be 40 to 70 degrees to prevent warping. You are not required to use a heated bed with PLA because it doesn’t contract.
Export
Once ready for the printer, slice the model one final time and Export .gCode for printer. Copy this .gCode onto the memory card for the printer.
Note: the printer does not recognize folders. Make sure to place the file in the main directory or you won’t be able to find it.
Setting Up the Ender V3 printer
Leveling the Bed
First home the printer
Second, disable the stepper so you can freely move the extruder and bed
Manually move the bed and the extruder to the 4 corners and center to ensure the bed is levelled properly.
You check by sliding a piece of paper between the nozzle and the bed.
You want the paper to gently catch but not rip (too tight) or slide (too loose)
When you adjust one corner, always re-check any corners in case the adjustment affects them too.
Once levelled, re-home the extruder.
Add Extra Grip to the Bed
For extra adherence of your material to the bed, you may want to put down some blue painter's tape (not green; green doesn't have as much grip).
Do this before pre-heating as the bed may get too hot to touch
If using tape, do not let them overlap. Apply them edge to edge. That can affect the height on which your model is being printed on, plus it's easier to peel when they're not layered.
Be wary of your hands - if they're too oily/dirty that may also affect how the filament adheres to the surface
Pre-Heating the Plate and Extruder
You can pre-heat the plate depending on the filament you are using.
It will pre-heat to the most commonly used settings.
You need to pre-heat the extruder otherwise you cannot load the filament
Loading Filament
Raise the extruder so it has room to extrude filament
Make sure you have a pointed tip as feeding this extruder tends to be trickier.
Remove the blue tap handle for easier line of sight sight
Pull back on the lever and feed the filament into the tube
Once in, put the tap handle back on and gently push the filament until it is extruded
When it stops extruding material, carefully pluck off the material and then re-home the printer to print.
Running the 3D Print
After plugging in the memory card, go to Print and select your file.
When starting the print, the important thing to watch for is that the first layer is adhering to the bed.
Make sure you have power to the machine during the entire print. If you lose power halfway through, it won’t restart your print.
You can pause a job part way through the print. However, if the filament stays heated in the nozzle while paused, it could burn overtime and clog the nozzle.
You can also adjust the speed in real time on the machine.
Cleanup
Should be able to pry off your model but if you can’t and it is on tape, you can pull the tape up to leverage it off the plate. You can also use a spatula to leverage it off.
Unload the filament while the printer is hot. Leaving it can potentially jam the extruder for future uses.
Clean off the nozzle of any excess filament that was extruded.
Make sure to return the USB plug and any small tools to the drawer.
To clean off your models just use some snips to trim off the excess material and sand with a high grit sandpaper to smooth out any bumps.
Troubleshooting
Here are some common trouble shooting tips in regards to set-up for the machine. There are many other problems that may occur in terms of print quality. This can vary greatly depending on the type of material you're using and the outcomes you're trying to achieve and is usually just a matter of trying different settings. For an extensive list of troubleshooting issues, visit this site.
Print not sticking to the build plate
The cause is usually the bed surface is worn so the material will not stick. An easy fix is to cover the build plate with blue painters tape. If that doesn't work, the build plate may need to be levelled.
Levelling the Build Plate
If the build plate is too far away from the extruder head or it is not level, the print won't stick to the bed.
Follow the leveling instructions from before.
Jammed Nozzle / Clogged Extruder
If the filament isn't extruding, the nozzle may be clogged.
Try manually pushing the filament through the nozzle, and then unloading and loading the nozzle.
If that doesn't work, try unclogging the head with a very small needle (like a sewing needle).
3D Printing Fees
Machine Run time: $2/hr with a minimum billing of $5.
Materials: Bring your own filament