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.



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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