3D modelling and printing
Sculpting vs Modelling
There are many takes on how to 3D model. Each with their own strenghts and weaknesses. Put simply there are two extreme ends of the spectrum:
- Sculpting: Like working en clay.
- Modelling: More engineering type strategies where the moddelling is about getting exact measurements and making precision mounts, flanges, brackets etc.
Often, when it comes to prototyping the latter is the preferred version.
3D MODELLING with tinkercad
Create and account and a new project in TinkerCad
At the moment the simplest tool for 3D modelling is TinkerCad. It is an online tool where one can design and model by combining a set of base shapes. Since you can define the exact size of the different parts you are able to make quick working elements.
Go here and create an account and a new tinkerCad 3D project:
For modelling the basic principles are sizing, subtraction and addition. They will be introduced below and there is a good video you can watch from a hands on introduction.
Create an object and define the size
Choose an object from the object menu. Drag the object onto the platform. Then click a corner to get access to its size. Changer according to your needs.
- Add another object to build your form.
- Select both.
- Use the allignment tool to make sure that both objects are alligned properly (black dots on the image - see video below for details).
- Pres the combine button to combine the two objects into one solid.
The menu where Combine, Ungroup, Align and Mirror is placed
- To subtract shapes one of them needs to be a hollow shape. To indicate which shapes is to be subtracted from which. Either pick a hollow shape or turn the shape into a hollow shape in the menu (see below).
- Select both shapes.
- Combined them like you did in the previous step.
Prepare your design for 3D printing
- Make sure to have one solid object: Often you end up with a combination of stacked objects, but they are not turned into a solid object. In that case you need to combine the objects into one solid.
- Make sure that it is realistic to print:
- Thin walls are hard to print and will warp in the printing process.
- Small nitty gritty details might be too small for the printer.
- A uiform shape is realistic - long complex details are not.
To 3D print the object you need to export it to a recognizable format. The OBJ is often the most used. Alternatively use STL.
Watch this video for a more detailed introduction to TinkerCad modelling
3D Printing WITH UP MINI 2
This introduction uses an up mini 2 printer as a case for understanding the principles of 3D printing. The principles are somewhat similar to most modern printers. Information about specific printers are avaliable online. Some parts and images has been taken from the Up mini 2 manual.
Below are all the steps neccesary for 3D printing. Be aware that you should go through every single step everytime you 3D print. It would be naive to expect the 3D print to be initialized and ready to go when you want to use it.
Plan for safety
3D printing is prone to fail, so there are some precautions to be aware off:
- The nozzle can be clogged leaving the printer in a state where it tries to push out filament while not actually printing anything.
- The actual 3D print can become loose on the heating bed. This will cause it to be pushed around on the bed by the nozzle.
- The heat is strong enough that it can cause a fire.
- Some materials elicit fumes.
Precautions you need to take:
- Don’t leave the print running when you are not around. Except if you have done multiple prior runs and know that there is a high probability that it will go well AND you got permission from the lab you are in.
- Place the 3D printer away from burnable materials.
- Place the printer in a well ventilated area.
Slide print board into the platform
The print board is there to make the print stick to the surface. Further it enables you to take out the prin and dismount the print from the board when it is done.
Calibrate the printer
Initialize to zero the different axis’s. With the up mini do the following:
- Hold the initialization button on the printer.
- Clicking the "Initialize" option in the software menu (shown above).
- When the printer is idle, press the initialize button on touch screen.
Initialize the printer
Calibrate the nozzle to make sure that it has a proper distance between to printbed. It will calibrate the height and some will also calibrate the level of the printbed.
During nozzle height detection, the print head nozzle will touch the nozzle detector to make measurement.
Choose (know) your filament
Be aware of the type of material; especially if you are working in a shared workshop. It might be the wrong filament in the printer and you can break the printer if you are not carefull. They need different "profiles" when it comes to the temperature of the nozzle and the heatbed.
The most common 3D printing method is using a plastic based filament on a spool. This is then fed into the printer. The most common types of filament are:
ABS (Acrylonitrile Butadiene Styrene)
- Temperature: 210°C – 250°C
- Strong and flexible.
- Creates unpleasent fumes & are non-biodegrable.
- Can’t be used without a heatbed.
PLA (Polylactic Acid)
- Temperature: 180°C – 230°C
- No harmful fumes
- Less prone to wrapping.
- More brittle.
- Can be used on a non heated bed.
- Has a tendency to clog the nozzle.
Commonly, cheap printers use PLA because they don't need a heated bed and more professional use ABS (and PLA). Read more about 3D printing materials here.
Make sure the filament is installed and not tangled
It is outmost important that the filament is installed properly.
- From the casette to the printer there should be a guiding tube.
- The filament should be winded up properly on the spool (often it is tangled which is hard to see).
Feed the filemant into the nozzle
The filemant needs to be prefilled into the tube before you start to 3D print.
1) Insert the filament from the spool into guiding tube, arrange the guiding tube as shown in previous page. Press the Material button on the touch screen.
2) Choose the printing material as ABS/PLA by press the Wheel button to switch between different materials input the filament weight by using the +/- buttons.
3) Click "Extrude." The print head will start to heat up, within 3 minutes. Its temperature will reach 260°C, then the printer will buzz and the print head will start to extrude.
4) Gently insert the filament into the small hole on the print head. The filament will be fed into the print head automatically when it reaches the extruder gear inside the print head.
5) Check the nozzle for plastic extrusion. If plastic is coming out from the nozzle, that means the filament is loading correctly and the printer is ready for printing. (The extrusion will stop automat- ically.)
6)Finally insert the guiding the tube in to the filament entrance and press the tube into the holding clip on the print head mount.
Load the 3D model
Be aware to place it on the bed in the most optimal way. Usually this is flat down on the surface with the least height. E.g. an mobilephone cover should lay flat on the surfae. However, this may cause problems to the finished result since the part placed on the surface is the most rough.
Print the model
Make sure printer is connected to computer through USB, Wi-Fi , an ethernet cable, and then loaded a model.
Be aware! The printing time is greatly dependent on the quality, infill level and layer thickness. In general most prototypes are fint with thick layer, miniaml infill and low quality. Newertheless, that with as low quality as possible. Then you can always go up in quality when you are closer to a finished solution.
When the UP software is slicing or sending data to the printer progress displayed on the status bar on top of the software interface do not unplug the USB cable as this will disrupt the data transfer and result in a print failure. The USB cable can be unplugged after the data transfer is finished