I am beginning to feel that I have managed to absorb at least some some of the information I have been reading about 3D printing. It’s proving to be a good example of an old dog trying to learn new tricks. As with my previous post, this is a ‘warts and all’ description of a raw beginner’s attempt to get to grips with the basics of 3D printing.
The first stage in developing my understanding was to learn about the ‘slicer’ software that is needed to convert a 3D drawing to a printable object. The role of this software is far more complex than I had realised at the outset, and it has a profound effect on the viability of the 3D model.
It is the slicer software that handles such crucial issues as providing a firm base from which the model ‘grows’ and ensuring that the deposition of successive layers by the printer can actually realise the desired structure. Not every 3D drawing can be produced as a layered model, since there are many cases where additional support is needed, such as when there are inclined surfaces or openings, as at windows and doors. It soon becomes obvious that the printer cannot lay down material over a void, because there is nothing to support the melted filament as it extrudes from the nozzle!
This is an important constraint, which slicer software attempts to overcome by providing various options to generate support structures automatically. Since it is also wasteful of material to fill volumes with solid plastic, when this is not necessary, the slicer software adjusts the use of materials, by generating infill of honeycomb patterns, to fill such volumes.
My first attempt at printing took a 3D model that I found on the web and I then went ahead, using the default settings of the software supplied with my printer. The result was a very heavy model with a lot of substantial support structures, filling in window apertures and other parts of the model, and a rather rough surface finish, especially on curved surfaces.
My reading very quickly demonstrated me that the ‘EasyPrint PC’ software, supplied with my Geeetech E-180 printer, is not a good example of the genre and is based on a print ‘engine’ derived from an old version of the ‘Cura’ slicer program. I have found, however, that ‘Cura’ is a well-regarded slicer program, so my next step was to download the most recent version and then to find out how to adapt it to my E-180 printer.
The All3DP website proved an excellent source of information and the tutorial on that site: ‘2018 Cura Tutorial – Deep Inside the Cura 3D Slicer Software’ by Dibya Chakravorty gave me a good overview and an understanding of what the software does and how to set it up appropriately. Next, I found how to set up the Cura for my E-180 printer on the howchoo website in an article ‘Using Cura with the Geeetech E180 mini 3D printer’, by Zach.
Now feeling more confident, I set about trying to print a very simple model, to test how well my revised settings might work. Once again, I chose to download a 3D design from the Cults website and then adapt it to my printer. The model I chose was a small 4-wheel carriage, with panelled sides. My aim was to make a small step from the types of models that I have previously been making by means of my Silhouette cutter. Below is a screen shot of the model as imported into ‘Cura ver. 3.6’ software, set up for my printer at a ‘fine’ 0.1 mm layer height:
There are several other settings, including the addition of a ‘build plate’, to ensure adhesion to the printer bed. For this model, I chose a ‘Brim’ type of plate, with a width of 8 mm around the outside of the model.
After preparing the ‘sliced’ file, I copied this ‘gcode’ file to an SD memory card and inserted that into the card slot on my printer. After that, it is simply a matter of pressing ‘Start’ and sitting back to wait … printing is a rather slow process! The first stage was to lay down the ‘brim’ plate and I was pleased to find that this provided a firm attachment to the unheated bed of my printer – which I had prepared by applying ‘blue’ masking tape.
Once printing was underway, there is nothing to do for a couple of hours. To occupy myself, I tried taking a photo of the printer nozzle, as it was actually laying down plastic onto the carriage sides.
My first attempt was too flimsy, because I had not realised the ‘fill density’ setting still applied to the ‘walls’ of the model, so I ended up with a rather skeletal structure. I soon spotted this and re-started with a 100% ‘fill’ setting and, after that, all went well.
Unlike my earlier attempts, there were no problems with bed adhesion, nor did I suffer any power interruptions, although I did look in on the progress from time to time, as experience has shown that things can go awry and produce a random mess of ‘frozen’ plastic!
At last, the model on the mat looked like this:
Note the brim around the base of the model and the in-fill of the windows, to provide support to the upper layers of the body. This in-fill was quite difficult to remove since, although very thin, the plastic is tenacious and somewhat determined to remain attached to the rims of the windows. Apart from this, there were few obvious ‘glitches’ and the overall ‘finish’ of the sides, with the panelling looked pretty good to me.
I’ll pause at this point, before a final clean up and then seeing how primer attaches to the surfaces.
There are several limitations to the ‘Cura’ software, in terms of breaking down a more complex model into individual components, such as wheels and so on. I am trying other packages including Slic3r, Meshmixer, and netfabb, so will report on my findings with these in due course.