The course content is designed to facilitate a working knowledge of the processes and steps on production of prototypes, from the inception of the concept, through modelling and all the way to the production of the physical model.Technologies Applied:
- CNC Milling Machine
- CAD Software
- STL Conversion or Stereolithography enabled software
- Manual design and process flows.
- Cobalt Steel Alloy (High Speed Steel/HSS) – for softer materials
- Tungsten Carbide in a lattice of Cobalt (Carbide) – for harder/more abrasive materials such as Titanium
- HSS end mills will wear out faster than Carbide ones – Carbide is a lot harder as a material.
- Carbide is more brittle than HSS and therefore requires more rigidity to avoid tool failure tool alignment is critical.
- Ability of carbide to withstand extreme heat allows for high cutting speeds.
- Up cut Spiral – tends to pull workpiece up. Preferred for cutting metal
- Down cut Spiral – Presses workpiece down. can affect chip ejection
- Straight Spiral – Ejects chips well.
- Flat end mill – Best for cutting flat areas with no scalloping
- Ball end mill – For non flat surfaces.
- Corner Radius end mill – Specialized for milling corners.
- Assessment of Concept: The concept was reassessed. It was deemed necessary to revert to first principles to find a simpler and more elegant solution. Man perceives his environment to a large extent, through touch. The entire human body is sensitive to touch, logically, we sought to take advantage of this by developing a device that would stimulate the senses of touch. With the intention of making the unit as accessible and as cheap as possible, it was decided that low tech solutions would suffice, and so Vibro-motors were selected for stimulation of the haptic sensors. (Fig 2a Vibro-motors Concept, Fig 2b – Tests on a glove interface).
- Modifications on the Concept: The concept was further simplified on the basis that the hands are not necessarily the most sensitive of the human skin surface, nor is it the most convenient for stimulation by such Haptic devices. It was determined that having a glove for such an interface would hinder the normal functionality of the hand. It was therefore decided that the device would have to be something more versatile and should be deployable on any part of the body. A series of tests on the sensitivity of the skin to touch were conducted on various surfaces from the hand, through the upper back to the neck region, upon which it was determined that even though sensitivity varied, one was able to distinguish and perceive the Vibro-motors with an acceptable degree of accuracy.
- Iterations on the haptic Strip: The choice of a final working concept was made on the basis of its versatility. It’s suitability and functionality was conclusively established during the tests on the early versions of the haptic strip. (Fig. 3 – Haptic Strip on hand). At this stage the haptic strip existed in its elemental form, this being comprised of the ICU – Arduino – Nano, the Input – output transmission and reception module – in the form of a Bluetooth module, and the Vibro-motors. (Fig. 4 – Components of the Haptic Interface). Subsequent iterations of the same ranged from the hand interface, to a strip on the arm, of which there were several versions depending on the materials chosen and of which it was decided that silicon would be best suited for the intended purposes. (Fig. 5a – Tensile cloth haptic interface, 5b – Silicon Haptic Interface)
- Conclusions and lessons Learnt: Not taking into account the various technical skills required to produce the prototype, and assessing the Project exclusively on the criteria of the resultant prototype, its functionality – as per intended design and its aesthetics, the prospects for future optimization of the prototype are realistic. It was likewise determined that applicability and use of such a prototype within certain contextual communication protocols was not farfetched. The intuitive nature of the patterns made for easy memorizing when the prototype was used. Further developments of this interface could be carried out in the direction of design of hardware compatible apps for devices such as cellphones and tablets. In addition, further work can be done with regards to miniaturization of the strip. This can be achieved by accessorizing the element as a part of inner ware such as lightweight vests once the strip has been thinned out to appropriate scales. In this instance, concerns still exist over the safe washing of such wearable technology, in light of which it seems appropriate to have the strip along with all electronics installed as a removable device which can be temporarily glued onto the vest or a long sleeved shirt. In such an instance, the wearable tech should merge seamlessly with the inner garment.
- The Prototype:
Assignment II is an assignment in which we were to make items of our choosing using the basics gained up to that point in time, these being the laser cutting process as well as the basics of press-fit. Inception: The process of 3D printing is fast gaining popularity especially with regards to prototyping where it has become a must have component if one is to make a prototype. Having a prototype printed out is essential to the process of design since it helps to actually feel and see the item being prototyped. In anticipation of various items to be used in the "City Project" field, I chose to focus prototyping on components related to the "City Project" Troubleshooting: Duration of 3D printing Process. Depending on the complexity of the item being printed, the process can either take just a few minutes, to several hours.
The modeling of the above captioned palm bracelet was subsequently instrumental in determining the ridiculousness of our initial assumption both in terms of utilitarian inconveniences as well as ease of use, not to mention the fact that it just failed to serve its purpose. Subsequent modifications forced the team to think more organically. This hands on approach enabled the team to acknowledge and understand the scope and limitations of the technology in use. Depending on the task at hand, I was able to optimize and subsequently better choose the means with which to make each respective prototype component. This outside the box approach to the prototype (heck, the box was thrown out entirely) was one of the issues in that it presented a steep learning curve to me personally. The optimization of the design is enhanced by the fact that the item becomes tangible and it can be tested (if printed to scale). This is one of the few shortfalls of the virtual environment and simulations in CAD software as a whole. The printing process is also limited by the dimensions of the printer used. For instance, the Ultimaker 2 Go has a build volume of 120mm x 120 mm x 115mm. Materials Used: Printing was done on Ultimaker 2 Go, using PLA (Polylactic Acid) which as it turns out, is one of the more commonly used 3D printing materials. The model was saved in STL format and was prepped for printing using Ultimaker Cura.
Lessons Learnt: The prototyping process is made much easier with the use of 3D printers. The choice of materials (of the prototype) should be taken into consideration during the printing process. The use of a resin laser 3d printers is a more accurate method of 3D printing.
TOWER – GNM
The assignment was to construct a tower using press fit laser cut modular pieces with a dimensional limit of 150mm on the length. Materials: Modular patterns were restricted to 3 patterns or modular units.
Pre-Design - Conceptual approach: The concept was based on attainment of the maximum height without compromising the structural integrity of the tower frame. with these two parameters as the basis, it was evident that additional stability could be attained by the use of a cross-pattern of "beam" structures. Horizontal elements were left out. Iterations and Re-Design: In line with the initial concept of simplicity, there were few iterations between the initial design and the final version.
Troubleshooting: The initial design had stability issues due to the initial proposal of framing the beams using continuous interlocking. This made the initial design heavy. Whereas the interlocking pattern was maintained for the base in order to keep the structure stable, the interlocks were discarded at the subsequent upper levels, making the structure lighter and allowing for attainment of increase height. Cutting & Assembly: Cutting out of the modular units was done using a laser cutting machine. The cutting process took about 45 min. The Team Credits: Whereas the final product was a product of active team work on the part of all team members, the cutting work was conducted under the guidance of the course supervisor Ivan Mitrofanov since at the time non of the team members could conduct the cutting works independently.