Computer Aided Industrial Design (CAID) modeling differs from general 3D modeling in that the files created must be good enough for usage as the base for eventual tool making and product parts mass production. As such, it needs to be highly precise.
The following are some of the guidelines that I use for most of my CAID modelling work. These guidelines are applicable to both Alias StudioTools as well as Rhino 3D industrial design 3D modeling programs.
1. Set and define the initial tolerance and modeling units of measurement
The initial tolerance and modeling units of the CAID modeling program must be aligned and synchronized with the rest of the downstream software and hardware, such as Mechanical CAD programs and rapid prototyping machines. This is to ensure that when your 3D files are transferred to the subsequent software (such as a Mechanical CAD program), the files retained their integrity. I have instances whereby when the settings were not set properly, the 3D CAID files that were imported into the Mechanical CAD programs have gaps and holes.
2. Define direction and degree of draft.
Draft angles should be built into the model. Since most of the drafted surfaces form the initial surfaces where other parts and surfaces are build upon, any changes made after their creation can be very tricky. Therefore it is always a good idea to define beforehand the direction and degree of draft angle before the actual commencement of the modeling. This is to ensure that the part can be mass-produced from molding machines.
3. Use the correct degree for curves and surfaces
Models must be built using the appropriate curve and surface degrees. Many output sources cannot handle surfaces or curves with very high degrees.
4. Filleting should be performed within receiving Mechanical CAD program
This is to simplify and reduce the possibility of data error incurring during transfer. Generally, solid modelers such as Mechanical CAD programs are better at handling fillets than surface-based CAID programs. Also these allows the flexibility to change the fillet radius where necessary.
5. Parts to be modeled separately
It is not a good idea to attempt to model the entire product as a single part (unless it consisted only of one part). Doing so will present lots of problems for the mechanical engineer/s whom which you will be handing the files over to. Better be nice to the engineer/s as you may need their expertise too!
6. The model/surfaces should ideally form a fully closed volume before exporting
Most MCAD works better with ‘solidified’ polysurfaces. Rapid Prototyping Machines including 3D printing machines can only take a fully closed solid, otherwise they may not compute accurately for machining.
7. Shelling should be performed in the MCAD
Most MCAD works better with ‘solidified’ polysurfaces. As such, they are far better at shelling than surface modelers (most CAIDs)
Well, these are the general guidelines that I adhere too. I make no promise that even when these rules are abide by, that the 3D files will be error-free. But, it does helps in reducing the frustrating troubleshooting phase that is so typical of the product design and manufacturing process.