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Digital technologies/3D printing/3D modeling- Beginner (view source)
Revision as of 15:15, 18 August 2021
, 15:15, 18 August 2021→Modeling for 3D Printing
==[[Digital technologies/3D printing/3D modeling- Beginner/Modeling for 3D Printing|Modeling for 3D Printing]]==
==[[Digital technologies/3D printing/3D modeling- Beginner/Modeling for 3D Printing|Modeling for 3D Printing]]==
It is very important, while designing, to be aware of the limitations of the manufacturing method which will be used to make your design reality.
It is very important, while designing, to be aware of the limitations of the manufacturing method which will be used to make your design reality. Since this article focuses on 3D modeling for 3D printing, this section will only focus on those considerations relating to 3D printing. If you are unsure how 3D printing works, it is imperative that you read through the [[Digital technologies/3D printing/3D printing- Beginner|Beginner 3D Printing]] page on this wiki for you to understand the concepts and considerations discussed below. If your design is to be used in (electro-)mechanical assemblies in which there are interfacing components, is also important that you understand three basic tolerancing concepts and to keep them in the back of your mind when modeling or more generally designing these assemblies. If you will not be designing mechanical and electromechanical assemblies, you can skip to the next subsection.
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# Form: The form of a part refers to the overall dimensions and the shape of the exterior surfaces of a component. Think of a flaw referring to form as a print that ended up not matching the base geometry that was used to create it in CAD due to adverse physical variables during the printing process. Examples follow:
## A ''sphere'' may end up slightly ''oval'' once printed due to improper cooling, etc.;
## A pillar might end up tilted to one side due to improper belt tension between the belt axes, etc.;
## A pin feature might end up too large to fit its mating hole due to the printer outputting too much material when producing the outer walls of the feature (the inverse can also be true).
# Position: Position refers to the distance separating a feature and an (ideally) meaningful reference (i.e.: the distance between a hole and the side of a part, or between two holes). Thankfully, flaws pertaining to position are rare on a properly tuned printer, as the printer does not have any information about existing references other than the build plate. If tuned properly, the printer will always print a feature at a position (X,Y,Z) distance relative to another feature, because that is what the gCode will tell it to do. You can imagine, however, that if the part is warped, the 'build plate reference' is no longer valid, and such, warped parts almost always have features out of position ''<u>unless the meaningful reference (interfacing feature) used in the design is not the build plate</u>''. However, since the build plate reference is such an important one to define the Z position of features (for the printer, that is), making your meaningful reference something other than the build plate does not always guarantee you good positional tolerance independent of warping.
# Surface: The surface finish of a part is a rather complex subject. In 3D printing, and for typical applications of 3D printed parts, it mostly refers to the mean (statistical) difference between the height of cusps and valleys on a part and their deviation from that mean, at a macroscopic level. The most important consideration is that when 3D printing, most surface finishes are quite rough (deviate significantly from the mean), and thus are sanded down considerably to knock out the cusps left by the printer. This post processing can negatively affect the form of the final part.
Note that ''<u>a proper mechanical fit between components demands a good tolerance on form, feature position, and surface finish</u>'', such that it is typically impossible to obtain a proper fit when 3D printing, and that if you are considering the 3D printing of critically interfacing components, 3D printing should not be used unless post processing <u>''is built into the design''</u>. For mechanical designs, you will notice that the main application is brackets. This is because brackets only need good positional tolerance on holes and mating faces, which 3D printing can almost always provide (the tolerance on form for holes is not that important since they are typically clearance holes). However, since brackets are easily laser cut, 3D printing brackets is only done under certain specific conditions!
=== Supports ===
==== Form and smoothness ====
As explained in the 3D printing page, supports are sometimes required to support overhanging sections of a print. Supports will also require post processing such as removal and sanding (if a nice smooth finish is desired). When designing for mechanical assemblies, it is important to keep in mind that supported sections might sometimes sag slightly, affecting the form of the surface being printed. Therefore, when designing (modeling), make sure that interfacing geometries (those for which the correctness of the shape, or form, is critical as it is interfacing with other parts) are not overhanging.
==== Hard to access supports ====
Soluble supports are practically never used in our Makerspace for prints. While they are cool and all, most designs can avoid containing supports that are hard or impossible to reach. Intelligent designs do not typically have hard to reach supports unless they are absolutely necessary, in which case soluble supports can be used.
=== Build plate adhesion ===
When printing, adhesion is one of the main considerations. Make sure your design contains an adequate flat section that, if used as a base for the print, will not lead to excessive overhangs. The Thingiverse hand is a bad example the way it is positioned in '''Importing Models''' section of this article, but the way the flat section of the wrist is designed, and considering the position of the fingers not overhanging (perhaps the pinkie is slightly overhanging), placed on the its flat wrist section, this hand model is expected to print properly without the use of adhesion or even supports!
=== Large prints ===
Extremely large prints cannot fit your regular build plate (or build volume). Yes, the makerspace does own 3D printers with larger build volumes, but those using them are typically charged for machine time. Instead, it can be extremely easy to split larger prints into smaller sections, and to then adhere these components together once they are all printed. The result might even look better, as sectioned parts can be oriented on the build plate to reduce the use of supports or improve adhesion.
==References==
==References==
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