3D Printing Lesson 2: What we can do at MakeICT
Currently, all of the 3D printers at MakeICT are Plastic/FFF/FDM or other names. What it means is that the material (filament) is fed into a hot end which is positioned and the material is deposited in layers to build up the object. This gives certain capabilities, and limitations.
Each of the printers has a hot end which works similarly. With most of the printer dedicated to positioning the hot end, and the the hot end heating up the plastic filament, which is pushed in by the extruder motor, forcing the melted filament out the nozzle. See 3D_Printing_Hotend for a picture and description of how the hotend works.
The machines have very good accuracy and precision, and are limited by the nozzle. Any 3D printer of the plastic type that MakeICT has, will use a nozzle, and the smallest that are in general circulation are 0.2mm. Those are actually rather rare, because at that small size, any dust or imperfections can clog the nozzle. The printers at MakeICT are 0.4 and 0.35mm, which provides a nice compromise between detail and reliability. As far as the vertical Z Axis, Each layer can be down to 0.1mm, or potentially lower, but 0.1mm is a rather practical limit to prevent prints that take a very long time. So the dimensions on your print can be very good. (The print may not be perfect, too much or too little may be extruded, and they aren't extruded as flat extrusions, there is some expansion after leaving the nozzle giving the cross section kind of a hot dog shape if viewed with the nozzle coming at you. Due to that nature, prints won't be perfectly flat, but they can be quite close to the dimensions.
At MakeICT there are 3 Printers, the oldest being the Reprap Prusa Mendel. Due to some design ideas that didn't pan out, and somewhat under-powered motors it has a slightly smaller print area compared to most printers of the same type, at about 160x160x50 as a safe size to use. It is a direct drive (which means that the motor is right next to the hot end) Cartesian bot (which means that it has an axis for each dimension (X, Y, Z). The nozzle is 0.35mm and it uses a geared extruder. It is the only printer that can handle the flexible filament, due to the direct drive, as well as PLA. However, ABS is not recommended due to the lack of a heated bed.
The second printer is the Ultimaker 2, which has been modified from it's original setup, to use 1.75mm and some upgrades were done on it. It has a metal hotend (allowing it to reach high tempatures) and a heated bed allowing it to print PLA or ABS. It is a bowden (much like a bike's brakes, it uses a tube to contain the filament, though in this case pushing into the hotend instead of pulling out) Cartesian bot.
The 3rd printer is the Rostock Max, which like the Ultimaker uses a heated bed and metal hotend, so it can print higher temperature plastics. It is a bowden Delta bot (meaning that instead of having an axis for each X, Y, Z, it uses 3 motors which move using a difference, or delta, in position to place the head appropriately.
While they have different styles, for the most part the use of the printers is the same, as the software makes the interface even for the code that runs them (gcode) almost the same. However, due to slight differences, the code while probably more than 99% compatible, is not compatible between the printers.
So the process of creating a 3D print starts with a 3D model, usually an STL file.
Usage process: Take good STL file Slice STL file in slic3r or Cura (link) Upload to the Raspberry Pi corresponding to the printer. (link) Log into the Raspberry Pi, find the file and tell it to print. (link) Wait Beautiful print comes out!*
- Provided nothing bad happens.
However, you will run into problems when 3D printing. It's not an if thing. Accept that. First, it starts by using good files. Good files being one where the slicer can easily determine what is the inside and outside. (Story of the dragon prints) Second, make sure that you aren't printing in thin air. Most 3D printers can handle 45 degree angles.
