Model Making Process- Putting The Pieces Together ( Part 1)

After sanding down what I could with the 20 or so parts, I began mocking up the final shape of my model with just masking and double sided tape. On the final day of CNC’ing, while I was waiting for  one of the machines to finish with my parts i decided to cut out a foam block which at the time i assumed would make up the internal structure of my final model. Using the dimensions from my CAD file which was basically what was left of my model once i took off all the parts that were to be CNC’d i had basic dimensions of the shape I needed. I gathered some scraps from the workshop, printed out the technical drawing and got to work. Using scraps from around the RMIT workshop, epoxy glue and double sided, the hot wire and the band saw, i was able to get a pretty accurate shape going for the inside of my model.  When i got home I sanded it down a bit more and was able to place the parts around it to get a good idea of the shape that the model was taking and where the possible areas for bogging would be.

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These images are were the first stages of putting the parts together. I decided the order to put the parts together were the sides, then work from the front and across the roof towards the back. This mean that if there were any mistakes they would be pushed towards the back of the vehicle rather the front. Using a bunch of g clamps and lots of 5 minute epoxy i got to glueing the parts together and the parts started to take shape. Some parts required more sanding than others so I pulled out the dremel tool to speed up the process. Image

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Model Making Process- Final CNC’d Parts

After about 3 Weeks the majority of the parts for my model had been CNC’d out from 4 different  CNC machines. While relieved that I was up to the final part of the model making process, the issue that I had to face here was that because each machine worked to different tolerances ,y used different drill bits, not all the pieces would match up perfectly. This was also the case for the pieces which required more sanding than others, human error being the main problem here from sanding too far.

I ended up with quite a large number of parts, a lot higher than the others in my class due to the size limitations of the machines as well as the number of undercuts the parts I had contained. Throughout the process i attempted to put these pieces together to see my model coming together.

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Through the following images you can see the sanding that was required on some of the parts. Some came out with very little sanding needed (>10 min) some needing small bits of dowel to get into smaller radius’s.  The hardest parts to sand where the ones which joined onto others through flimsy joining areas, these were only able to be sanded properly once the parts were glued to each other and required very careful handling to minimize bogging later. I sanded here using 80- 240 grit paper. 80 grit for the really rough stuff and 240 for getting the parts ready for paint.
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Model Making Process- 3D Printing

For many of the smaller details of my concept vehicle such as headlights and logos, these were much easier to be 3D printed rather than CNC machined out due to the accuracy needed in the shapes and the freedom with design you had. The two machines that I had access too were a Z- Corp and a Objet Printer.

The Z-Corp was a white powder printer which was able to print objects down to 2mm with quite alot of accuracy. The common working process with these parts was to collect the prints and then coat them in an Epoxy Resin which after drying allowed them to harden into a material that was much easier to sand and consequently paint with better strength. These prints were generally cheaper than the Objet Prints however the smaller you went, the weaker the prints were, my taillights originally being printed in Z Corp, had the consistency of a baked cookie, crumbling and bending at some points being generally far to fragile to work with.  Noting the weakness of the smaller parts, the 3 larger prints that I needed to create were completed on the Z- Corp Machine maintaining a wall thickness of minimum 3mm all around to ensure rigidity in the printed structure.

The Objet Printer was an additive manufacture printer which printed in a polymer like material that was alot stronger than the equivalent Z-corp of the same size. Being costlier due to the support material that surrounded each part that was created, strategically placing parts flat on the bed was crucial to saving money. The parts that came out of the Objet were a translucent yellow polymer/plastic that took a while to clean but felt much stronger and flexible to work with than the Z-Corp Prints. I ended up using the Objet Printer for all my smaller parts as whilst the cost was slightly higher, the strength of the parts paid off due to the easy of sanding and painting them.

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Model Making Process- CNC Machining Part 2

Realizing some parts of my model were quite tough to machine out without creating alot more individual parts than I already had, I had to look around for other machines that I could use. The RMIT TAFE up the road actually had access to a larger Roland CNC Machine that cut using 4 Axis. This meant that the parts that could be cut out on this machine could be rotated to allow the drill to access parts which were originally undercuts.  This machine being bigger was a great help for helping to create the outer wheel pods of my concept with the help of the Technician who allowed the machine to run overnight, saving me a bunch of time.

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The program used here was called Modela. This program was taught to the Product Design students at the Tafe and was extremely helpful. It was a simpler program compared to SurfCam only requiring experience to know how to push the machine to work that little bit smarter than usual

The RMIT Gossard Workshop also had a Roland Machine which was a 4 axis machine but was often used as a 3 axis. This machine which I ended up learning how to use by myself, had rather simple interface but still took a bit of fiddling about to get it working perfectly. This machine was able to create very good finishes on parts but being a smaller machine with smaller drill bits was quite a bit slower.  Through using this myself I was able to learn to run tool paths through the SRP Player and also where I could push the machine to work faster or slower depending on the complexity of the part. By the end of the project I felt confident enough to run the machine entirely by myself and was able to run other students project parts awell.

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Model Making Process- CNC Machining

The 4 Machines that I was lucky enough to use at RMIT’s workshop ranged from 2.5 -4 axis CNC machines of varying sizes. These included 2 Roland Machines, a Haas and an ART Router.

The ART Router or the big yellow CNC machine as i called it, was a large 2.5 axis machine that was relatively quick but at the expense of detail. Used to cut out the big sides of the 3d Model, the job took approximately 7 hours and wasnt without error and many tense moments. It had troubles cutting sharp gradients and sharp small corners as the step size between the tool paths were quite big meaning more sanding for myself afterwards. I was more happy just to see my model take shape! The files for this machine were IGES prepared through Rhino and toolpaths were run through RHINOCAM before being sent to the machine.

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The Haas Machine was a 5 axis CNC Machine converted to 3 axis which we made good use of. This machines bed size was alot smaller than that of the ART at about 300 by 300mm, but was a quick cutting machine with a very good finish requiring minimal sanding. This machine was great for the smaller more detailed areas of my model where drill bit size and length was an issue. Due to the speed of this machine almost 50% of the parts were cut out here as the post CNC work was minimal. Unfortunately this machine was alot more complicated than the others to run with tool paths needing a qualified technician to program. The program used for this was SurfCam.

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Model Making Process- CAD for CNC

After refining my final CAD model a number of times, cleaning up surfaces for rendering and updating and design changes, the 3D model was ready to be CNC Machined. Lucky enough our uni RMIT has a number of CNC machines at their disposale ranging from high speed small scale 4 axis machines to large (2.5m+) 2.5 axis machines able to churn out large parts in a matter of hours. Due to the size and axis limitation of these machines a full 3D model is unable to be cut as a single piece through to these machines. This meant splitting or ‘slicing’ up our 3d models into more manageable sizes that would make the best use of each machine. Examples of this were sending the more highly detailed parts onto the smaller machines which had the drill bits which were small enough to cut out the details needed.  This was also the case when a particular piece was easier to machine on a 4 axis machine rather than a 3, perhaps because it saved time or produced a higher quality result.
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The form that I had ended up with was quite long and had many undercuts which resulted the large number of CAD images you see above. Where as some students in my class were able to cut their model from less than 10 pieces, the design of mine included many undercuts which made splitting my model quite a task in itself. At the end of the CNC process I had cut out almost 25 pieces on 4 different CNC machines over 3 weeks. I had considered getting some parts outsourced to save time however the quotes that I received back were quite unreasonable, one place asking for upwards of $6000 and 3D printing being even more expensive. With the time constraints I was under and the  iffy nature of these machines, some parts did end up getting 3D printed to save myself time at quite a considerable cost at the university. In hindsight completing my CAD earlier would have prevented these extra costs but it was a good learning experience

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Model Making Process- CAD Process

Throughout the concept development process it was important for me to create CAD models to help visualizing my ideas through other mediums apart from sketching. This gave me the ability to block out forms quickly and utilize it as something that I could sketch over to refine certain shapes that I liked. 

I used Autodesk Alias to surface my model for my major project this year after learning to use it for a semester in 2011. I believed that this program was the best choice as it was a sought after skill in the automotive industry. Using online tutorials and the help of some friends who were also learning to use the program I was able to skill up to a level that was high enough to enable me to surface a form that could be transferred for CNC machining as well as CAD rendering. 

The top half of the images represent the earliest CAD models where the surfaces were created more to show form generation rather than clean surfacing. The later half represented a CAD model that I intended to use for both CNC Machining and Rendering with much cleaner surfacing and better reflections. 

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Major Project- Package Development

As seen in my previous post, you can see my form development change and follow various directions, some following a single form others a more random shape usually inspired by and organic shape. 

The following upload represents the first semester vehicle package development. I took inspiration from the stylish people movers aswell as standard passenger cars for a blend of style and function, especially in the interior. After purchasing two car seats I was able to live out my package drawing in my driveway placing the seats in a 1:1  package drawing in chalk and using some friends as measures to go by. As you can see the package took a number of different forms due to the various design choices I made through the semester this usually involving varying the number of occupants.

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After further evaluation of my interior I narrowed the number of people from six down to four. This meant that I could properly refine how these four people were to sit in the interior and mark out the space that they all required. This involved further testing with people in the measured out interior as shown by the photos and looking at the kind of seating arrangements that I thought were useful for a driver less car. My aim was create an interior that reflected the new age of automotive development where everyone was a passenger and I really wanted the feel of the interior to reflect that. Here i seriously began thinking about the technologies that were to be a part of the car and certain ” car” bits such as tires and power train and including these in the thought process so that the end result was realistic. The form I presented at my Mid Sem Critique was also refined into a proper package here as well. 

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The following sketch was the turning point at the middle of the year, altering my mid semester form into one which was sleeker captured the speed of the form that i was looking to achieve. This sketch was made over my previous vehicular package and modelled in clay, beginning a major design change.

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After this major design change, most of the updates to the package were made to purely reflect the current form and to make sure whatever design I was pushing had a level of realism according to the package. One of the main design considerations I made after mid semester was to reduce the number of seats that had rotational movement. Initially all four were designed to move but after further analysis I realised that only the front seats needed to be able to move to create an interior theme that was more social. Allowing rotation in all seats meant a much wider vehicle that would lose the newer proportions i was aiming to achieve. Having movement in the rear seat I believed didn’t add much to the overall social mood of the vehicle and what movement there could be would be quite limited regardless. Final power train dimensions, tire sizes, door trims, headlight and tail lights were all finalised here in tune with the refinements in form development.

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Major Project Sketch Development

After the Mid Year Critique, I took another look at my vehicles package and began cutting down and creating a leaner, sleeker form. Inspiration came from not just the package however but also my clay model which I had been working on for the 5 months before that. In the market segment i was looking at too, concept luxury vehicles such as the Peugeot HX1 and the Citroen Numero 9 were vehicles whose captured the sleek fastback form that I aimed to create for my concept.

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This is a selection of sketches which show the initial change in form from the previous packaging. I explored a much sleeker variety of shapes daring to be a bit more conceptual that previously.

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Through these earlier sketches i began further refining my vehicles package looking at where needed to be higher or lower , longer or shorter. I took some of the forms you see above and refined them further into something that started to hint at my final form.

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These forms above have begun to capture the sleek lines I was looking to create and have begun including proper provisions for wheels and doors etc. Details such as headlight and tail light placement, window line, suspension arms were beginning to be considered at this point too.

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These sketches here show the overall form I have chosen and the refinement that went along with it. Sticking with enclosed wheels with in wheel electric motors and a large glass house which reached down to the front bonnet area I was able to adjust my packaging to allow for the forms shown above to be viable. Further refinement here included proper tire sizing, door openings, interior space, power train and suspension placement for the package.

The vehicle graphics such as the side profile was important to refine here as the connection between the front and rear “pods” which housed the wheels, dominated the side profile. Further smaller graphics such as head and taillight placement as well as functional venting was also refined at this stage.

Clay Modelling- Transport Elective

As mentioned in the previous post, studying Transport Design at Monash University as an elective really opened my eyes to rapid form development and getting a better understanding for form and surface. 

The brief for this semesters class was to create a “Speedform”. To everyone this has a different meaning and I think it was interesting to see how people interpreted the brief. Personally when i think speed form i think of an older generation of muscle cars which were long and low , with strong lines and simple aggressive styling. I went further back to looking at hot rods too and capturing the old meets new as you see in hot rods and rat rods of today. This became my mindset for the project, thinking of creating a futuristic vehicle with a hot rod look, containing the old school curvy wheel arches that were so prominent of that generation of vehicles.

 

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