Designing a Custom Built 3D printer in CATIA
Using CATIA, open source software & electronic & hardware components
Sam Suchal, a third year Mechanical Engineering student, decided on a whim to see whether he could use a combination of CATIA, open source software and electronic and hardware components to build his own 3D printer – as 3D printers are frequently in demand on campus, he thought “why not build my own”.
University College London (UCL) has numerous long established relations with the commercial world which enables its students to gain practical, hands-on experience beyond the class room environment. One such relationship exists between UCL Mechanical Engineering and leading engineering software solutions provider Desktop Engineering.
UCL Mechanical Engineering uses 400 student and 35 academic licences of CATIA V5 from Dassault Systemes. Components commonly used by students include surface design, assembly design, mechanical design, FE analysis and modelling. CATIA was chosen by Dr Baker as he sees it as the “industry standard”. The emphasis of the course is geared towards teaching practical engineering, with design and CATIA at the heart of that focus.
Where to Start?
When researching the feasibility of the project, Sam’s first stop was Rapid Replicating Prototyper (RepRap) – an initiative launched in 2005 which focuses on making self replicating machines. RepRap takes the form of a free desktop 3D printer capable of printing plastic objects. Since many parts of RepRap are made from plastic and RepRap prints those parts, RepRap self-replicates by making a kit of itself - a kit that anyone can assemble given time and materials. The initiative has assembled a large community of printer enthusiasts and generated a lot of useful resources as well as an endless list of various designs and open source code.
Many of the projects where 3D models of real-life applications are made (especially at university level), remain in the virtual form of 3D models. Manufacture of prototypes and components is costly, time consuming and requires facilities that are not normally available.
As 3D printing technology has improved there is now more of an opportunity to transfer a 3D model created in CATIA into a real, solid prototype or component that can be used as a part of a bigger project. 3D printed objects are usually plastic and do not possess very good structural attributes compared to other materials, but for most applications they are just as good or even better because they’re light and can be endlessly customised. For Sam, this was one of the main motivations to create a working 3D printer - the ability to create a solid object that can be modelled in CATIA.
Using CATIA V5, Sam began work on designing and manufacturing a custom 3D printer. The design process was driven by access to a sheet metal processing facility that allowed most of the structural components to be manufactured from sheet steel.
The design was vaguely based on the Prusa Mendel i3 design with some major changes – chief of which was the use of high-helix leadscrews instead of timing belts for linear actuation. High helix leadscrews were chosen for several reasons; they are as accurate and reliable as timing belts, but are simpler to install and maintain, plus they create a cleaner design. In addition, the use of timing belts required a fairly complicated system of pulleys that needed bearings and mechanisms for tightening, where as leadscrews simply attach to the stepper motor using a shaft coupler. On the downside, leadscrews are more expensive than timing belts and can transfer vibrations to the actuated components, in this case the printed part.
The design process took around two months of 3D modelling work and the resulting 3D model of the printer consisted of 664 components (139 unique components) which were created using various CATIA workbenches:
- Part Design to create components
- Assembly Design to assembly components together
- Generative Sheet Metal design to easily manipulate sheet metal components
- Wiring, Cabling and Harnessing workbenches to ease the planning of cable routing
- Electric component design for electrical connectors and;
- Structural analysis and FEA workbench to determine the structural rigidity of crucial components.
The 3D model was then used to produce full documentation for each manufactured component. The main structural components were then laser cut and bent into shape from stainless steel. After assembly of the structural components, wiring and electronics were installed. This process was simplified by CATIA, since it can used to model the cabling and wiring harnesses in the appropriate workbench. The machine was then tested and tweaked both in terms of mechanical components and firmware adjustments.
A few electronics were bought readymade, including the main control motherboard which uses an Arduino and a special shield, and some were soldered from separate components such as endstops, which tell the printer the position of the nozzle and print bed.
The End Result
Now completed, the 3D printer is capable of quality prints and can roughly achieve the same printing speed as commercially available printers. It is also reliable enough to print medium sized products (longest test was five hours printing).
The design was also successful in terms of component manufacture. Once the steel components arrived from the manufacturing facility, there were no issues or additional customisations required. This can be attributed to CATIA functionality which allows the user to analyse the final product before it is made – something which was impossible using old fashioned technique of 2D design and drawing.
Dr Tim Baker concluded:
At UCL Mechanical Engineering we endeavour to push our students to design something that results in an end product and to do this we need the latest technology. Solutions like CATIA help us deliver graduates that are more than capable of handling the day-to-day challenges of the work environment. Sam’s design of the 3D printer is a great example of creativity and technology working together, he has demonstrated a can do attitude which is something we actively encourage on the course.
During the working week I wear both an academic and a commercial motorsport hat and know DTE from previous work that I have done in the industry. Back in 2002, I was looking for a CAD solution and came across DTE due to a colleague’s recommendation. Since that day I have worked with DTE on a regular basis and have always received a great service. I always find they’re willing to go the extra mile in terms of helping our students with their design projects.
Dr Tim Baker, Lecturer - UCL Mechanical Engineering
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