1. Requirements

Introduction


One of the things I am passionate about is Robotics. I want to apply whatever I learnt in school into reality, that is to turn them into reality whatever came into my imagination and whatever & whenever the need arises.
Beatty-Robotics is one of my main source of inspiration. But here in Singapore where I live, space is an issue. Let alone my budget. I will have to start from the ground up without anyone’s help for now. So how do I even start creating and make my own robots in the first place with such limited space and budget? I cannot afford a CNC milling machine. Where do I put it in the first place living here in high rise flats?

The Answer? A 3D Printer!


The Answer? A 3D Printer. I have three choices:

  1. Buy a Plug & Play 3D Printer (Fully fledged product eg. Ultimaker, markforged)
  2. Buy a 3D printer Kit (Assemble it Yourself eg. Tevo, Tronxy, Creality…)
  3. Design and build one from the ground up

I chose the third one. Just to get the idea, I will briefly discuss the first two below. Do note they are my opinion. Biased? maybe…..

Section 1: Plug & Play

I would like to define Plug & Play 3D Printer as a product that is comes right out of the box functional, without the need to hassle with any sort of troubleshooting. An example would be Figure 1, an FDM-Technology based 3D printer that is rugged and designed to work right out of the box. They come in complete without any imperfection with parts properly quality-checked. Another example would be Cel Robox.

Advantages
  • First, as the name suggest, it runs right out of the box
  • Secondly, they are stable platforms, one that runs smoothly. If you have any issues pertaining to their product, they will have theur own customer service to help you out. There is warranty too. Some include return policy too.
  • Depending on the technology used, the print quality outcome would generally be better than ones from kits albeit some are top of the line (eg. markforged , Stratasys).
Disadvantages
  • Most are closed source which means that the design drawings, cad files, firmware are not open and accessible to people.
  • Expensive for the build volume you are getting.
  • Ultimately, you’re stuck with what you have and what they provide you.

What bothers me so much are the disadvantages. Furthermore, what fun it is to just buy an off-the-shelf 3D printer and use for your projects?
It is great for beginners who just started learning 3D Printing let alone even 3D modelling eager to put their imagination into reality.
If I were to purchase one, I’m virtually limited to the filament materials that are recommended on a particular machine. Plus, I will not learn anything new. Build volume is another thing bothering me which I will discuss in the last part.

Section 2: Assemble it Yourself kits

3D printer Kits are plentiful now on this planet. Just do a quick search in google 3D printer kit and the results are thousands especially those from the Far-East (China). Companies like Tevo, Creality and Tronxy are examples to name a few.
For this section of 3D printers, there are two sides of the story. Some are great platforms, having stability and awesome customer service ( Prusa I3 of Prusa Research and Lulzbot of Aleph Objects).

I would like to focus on the other side: the not so good one (dependent on your requirements). Once bought and received, you get a set of prefabricated raw materials such as laser-cut bracket made of acrylic, cut-to-length aluminum profiles and so-on.
Next step is assembly. Here is where the issues come in. Most that are bought from the Far-East are riddled with issues.
Some have missing screws or screws in which are not enough to fully assemble the kit.
Some have issues with unclear instructions on assembly steps if not confusing.
Build quality for the most part is unsatisfactory. In 3D printing technology, one key aspect of getting a good print quality be it surface finish or/and precision and accuracy is rigidity.
Albeit such issues, one plus point is that you get to learn how a 3D printer works and functions from the ground up, from knowing the raw materials used, assembly to setting up the firmware.
Another is the price. It is cheap/affordable. It is after all a commercially available RepRap, or those in line with the RepRap Project.
Having said that, with the issues I pointed out with buying a kit, I choose the third option!


From the Ground Up


My requirements are fairly demanding.

Filament Material

If I were to go for the Plug n Play route, I will be limited to the filament materials that are recommended for a particular machine. On the 3D printer I will be using in the future, it needs to be able to print “Usable materials”. PLA, ABS and PETG are common materials used in consumer and hobbyists 3D Printing and are easily available. However, these materials lack strength, toughness and durability for the kinds of things I will be making- robots, rovers- that are expected to last and endure not just through time but also the environments it is expected to run on and into.
For example if I were to make a robot/rover out of ABS and have it operate outdoors, it will degrade overtime when exposed to Sunlight (UV rays). [1]
Materials such as Polycarbonate, Nylon, Ultem and even those that are Carbon-Fiber-Reinforced are very demanding in requirements such as the need for Heated Bed and an enclosure to prevent inhalation of Toxic Fumes.

Print Bed

Having said about the heated bed, the build platform needs to be Large at 400mm x 800mm in area. Having such a large build platform allows me to design and fabricate large parts in a single print without needing to break it into several pieces which compromises on part strength.
Build height is not of a concern. While some commercially available 3D Printer boast large print volume in which print height is higher than the length of either sides of the print bed, I do not need to print tall objects or parts ( Tevo Little Monster).


A fairly large and wide build plate will also allow me to have two independent x-axis carriages where each carriage carries an extruder (IDEX) (more later on). Having an IDEX 3D printer will allow me to clone a mirrored part while the actual one is being printed, reducing total print time to fabricate a robot(Leapfrog). [2]

Quad Extruders

I need 4 Extruders in IDEX configuration with each carriage carrying 2 extruder/hotend depending on the setup (Bowden vs Direct Drive).

  • 2 for Difficult materials. Eg: PC, Nylon, Ultem……
  • 1 for affordable and not-so-demanding materials. Eg: PLA, ABS, PETG….
  • 1 for suppport material. Eg: PVA…..
Build Quality & Rigidity

Lastly, it needs a strong structural rigidity and build quality. It is key to obtaining high quality print results along with being able to print objects at a higher speed than that if it was to be done on a flimsy one.
There are two choices:

  1. One made of Machined Aluminum for all parts
  2. One made of 3D Printed materials such as Nylon or Polycarbonate at 70%-100% Infill
Cost

My budget is SG$1000-SG$2000.
However my budget will be of the lowest priority. Viability due to cost will be determined when a design is matured enough for quotations to be made.


As with fulling the above requirements, I will have to do some design experimentation in CAD software to further understand each design’s viability in fulling the requirements above.

References


 [1] Angus Deveson. www.makersmuse.com/thebasics.html
[2] www.lpfrg.com/en/benefits-of-independent-dual-extruders/

Figures


Figure 1: Up Plus 2.
Figure 2: Tevo Tarantula
Figure 3: Rendering of my 3D printer

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