3D printing Part Four
Beware downloading 3D printing projects, there may be hooks
Some weeks ago I recorded a very enjoyable chat with Lino Zangirolami. Lino is a 71-year-old Italian friend of mine, and one of the most versatile creators of things I have ever met. He has the ability to make any kind of mechanism and automated machine. Recently, we have been working together on some electronic projects.
We talked about many topics, such as his career, 3D printing, CAD design, CAM, and more.
As I continue this series of articles about 3D printing, I will include suggestions and comments from my conversation with Lino along the way.
Designing for 3D printing
3D-printing technology is a great opportunity for all: makers, students, children, hobbyists. But what should we print? After finishing the assembly of the DIY 3D printer in the previous three articles, we should test it, and then start using it.
As discussed before in this series, all the mentioned examples are available on the Shed Mag Git Hub repository https:// github.com/alicemirror/ShedMagazine. You can find literally hundreds of thousands of STL (stereolithography) ready-to-use model files on the internet, downloadable for free. Any kind of box for the most popular electronic boards
(Raspberry Pi, Beagle Bone, Arduino, Micro: bit, and more), as well as puppets, buildings and monuments, mechanical components, gears, and great playable games, etc., are available.
I have used these resources many times and, based on my experience, I should warn the reader that not all the material available on the internet is good. After downloading and trying to print some models, I realized how many of them are purely theoretical projects. As a matter of fact, 3D printing many of these proposed projects is often difficult: design errors, wrong parts and proportions, and objects that are impossible to print are only some of issues I found. A tip from Lino:
“Suggestion: when downloading an STL file from the internet for your personal use, before trying to 3D print it, wasting time and filament, choose the ones that include some clear images of the finished and assembled work. Never trust the 3D-model simulations only!”
After finding a ready-to-use STL file, it is very rare that the design perfectly fits my needs completely, and some changes are needed. But STL files — the rendered format of a 3D-model — can’t be changed at all. The files should be imported as is into the 3D-printing software.
Trying the available models online may be a good starting point and a great source of ideas and inspiration. But be
In many respects, we can consider 3D printers, and CNC routers and lathe machines applying complementary technologies. In both cases, moving from one technology to the other is not so difficult; by a procedural point of view, the principle is always the same: design a 3D CAD model then export the file in STL format for 3D printing or create the tool path for material machining. In the case of the CNC machining, the extruder is replaced by the tool. The great difference that should be considered in the design phase is that 3D printers add material by layers on a flat bed while the CNC routers subtract material from an original piece.
In my opinion, it is easier to move from the 3D printer experience to a CNC router, a more complex machine requiring control of more variables to reach good results.
“During the years between ’94 and ’96, I funded a small jewel-cutting company. In that period I represented a vanguard as I bought one of the first semi-automatic machines for stone jewel cutting from Germany. I self-learnt the needed knowledge and acquired the experience to manage those machines. Thanks to a sort of natural feeling with computers, after the first C64 I always continued to evolve and update my knowledge, from the first BASIC programming up to the most recent Windows 3D-modelling application and CAM controllers”
prepared to design your own model to achieve the results you want. Excluding those rare cases when you find exactly what you need (or you decide to adopt some compromise), the much better solution, in my opinion, is to design the model yourself.
The LED ring
A couple of months ago, I developed a very simple project based on 3D-printed components to make an LED ring for my camera to shoot macro photography and close-up portraits.
I designed all the parts, then printed
After downloading and trying to print some models, I realized how many of them are purely theoretical projects
them at home, and the tests were satisfactory. To fix the LED ring around the camera lens I made a 3mm-thick perspex bar (www.kitronik.co.uk/ materials.html) to be screwed to the camera flash socket. The solution worked well, but it was not aesthetically pleasing. I searched on the Thingiverse site for some kind of alternative solution, or some inspiring project, and downloaded the Iris Box created by Brien Allison (www.thingiverse.com/ thing:2479617) aiming to make an iris to keep the LED ring firmly in place on the camera lens.
Why choose this project? Because it is one of the rare cases where the author, as well as the STL files, has also released the original CAD design.
Consider keeping the 3D printer powered off for a while and start playing with some CAD application. For about three decades, I have been experimenting with a lot of different
programs and 3D environments, following the evolution of 3D-modelling software. To date, the scenario is very interesting, not only for professionals, but also for makers and hobbyists.
During the past five years, the number of free CAD applications supported by the open-source community has grown considerably. A number of commercial CAD producers have also made available free versions of their commercially licensed software. This change has been influenced by at least two main factors: the growing popularity of low-cost 3D printers, and the large diffusion of the maker’s culture through a number of powerful and active online personalities. Makers’ communities have strongly influenced this trend.
In the next three articles, we will explore and test the best and worst options available to create 3D models from scratch for 3D printing.
Planning the 3D design
One of the first things we should consider when planning to design 3D parts ourselves is following some methodology. That’s not complex, but if we have a clear path to follow in our minds from the very beginning, the job will be faster and easier. The design approach is separate from the 3D application we will use in printing. When planning the design, we should be aware of the 3D printer set-up aspects discussed in previous Shed articles, as well as something else, specific to the design phase.
The first suggestion is to have a clear picture of the final object before starting the design. In the preparation phase, measure exactly all the non-3D printed components that will be part of the project — inserted parts, screw diameters and length, hole diameters, bearing sizes, etc.
It’s a good idea to make a paper draft of your design idea and write down the quotes, as shown in the design draft, and 3D-rendered sample images pictured here. As you can see in the draft, I have measured and drawn the design on paper, then used it to create the 3D model.
Before proceeding with the CAD software, there are still a couple of things to consider — the 3D printer settings and filament features that will be used.
These parameters affect the aspect of the 3D model and vice versa. It is easier to explain with some examples:
• Shell layer thickness: 0.6mm. This means that designing a surface of the 3.5mm-thick model will be printed 3.6mm thick, which is different from what we expect.
• X–Y axis horizontal movement resolution: 0.1mm.
This means that the solid dimensions should be designed accordingly. A solid block measuring, for example, 7.55mmx4.03mm will not be printed as expected. The slicer software will probably create a real object sized 7.6mmx4mm.
One last design point we should consider is the size of the parts that will fit together or connect to other components (pins, screws, bearings, etc.).
The 3D model is a theoretical representation of a real object, created by fusing a plastic filament. For example, if designing an 8mm-diameter bearing seat, you should consider a diameter of 8.2mm instead.
When designing extremely precise models consider the kind of material and process applied to the real world — if you take the time to do this it is possible to save an incredible amount of time in paper sanding and finishing the 3D printed parts.
For the software download of this series of articles, head to https://github.com/alicemirror/ ShedMagazine.
One of the first things we should consider when planning to design 3D parts ourselves is following some methodology.