A 3D printer works additively, it melts one on the other very thin layers of plastic that merge to form the object designed using a software of computer-aided design (CAD). If you buy a 3D printer, the process does not stop to introduce a file, a filament and marvel at the work produced. It’s not a 2D printer that just feeds leaves and ink, far from it.
Indeed, this additive manufacturing method must be taken into account when designing the file in order to make the most of it. Contrary to what one might think, it is not a limiting constraint but a tool, which, mastered, will allow you to manufacture an infinity of object of a high quality and solidity, sometimes realizable that by this tool. The 3D printer allows us to do everything we want BUT not always as we want.
That’s why you need a lot of control when designing the object to take into account how the printer works and use all the assets. To do this, here are two main elements to consider in the design: the “way” in which the additional manufacturing and the tolerance of this manufacture is made.
The different directions of manufacture
When we talk about the “way” of the making of the object, first of all we think about how the layers are superimposed on each other. For most 3D printers, this overlay is from the bottom up. When you slicing your file to make it printable, you will need to determine the position of the part that is most suitable for that production. Of course, what is printed first, what rests on the board, it is not necessarily the “bottom” of the piece, all depends on its shape.
Before this formatting step, you can already consider this additive manufacturing constraint from bottom to top by designing a part that already has an ideal part to rest on the plateau. Again, that does not mean that it’s the “bottom” of the piece, it’s just a matter of designing it, taking into account how it’s going to be made. Designing a piece by imagining a place where it can be flat is not always possible, if it is not, do the best so that the printing can fit on the tray and, at the time of the formatting , add support to help the piece print correctly. However, before adding support, improve the room as much as possible so that it is its own support, using the arch system for example, it will only be more resistant.
There is another aspect concerning the orientation: during the printing, the filament is deposited in thin layers of a width of a few tenths of a millimeter. To make a complete layer, the filament will “draw” several “lines” to fill the requested space. The nozzle will therefore move in different directions to fill this space. Depending on how these lines are oriented and organized, the piece and more or less resistant in its different angles. Learn how to use the formatting software to position your room to use the lines to make your room ideally resistant. Depending on the software you use, you will be able to find different ways to fill the space for different needs.
Accuracy, precision and tolerance
When CAD, each recorded measurement corresponds to the so-called true value, that is to say the exact value expected during manufacture. However your printer has some tolerance and some accuracy. The expected accuracy will therefore be constrained to these two aspects.
Tolerance is the difference between what was designed and what is printed. It is defined according to the needs of your room: the more the room requires accuracy, the more it will require a low tolerance. I advise you to do tests to define this tolerance according to your needs, for example by printing small parts of your room, before printing everything, to help you in a better design and avoid having to redo everything every time.
Precision can be defined as reliability in the repeatability of a single measurement. If your tolerance level is between 1 and -1, but on each layer you systematically observe a deviation of 1 from the true value, your accuracy is high. Conversely, if your printer prints each layer with a different gap, your accuracy is low. The higher your accuracy, the more complex geometries you can print. As for tolerance, do not hesitate to do some tests to help you correct your design.
The quality of your printer is often responsible for both aspects. If you need production with low tolerance and high accuracy, consider printing on a high quality printer.
You now know what points to consider when designing a part before printing it in 3D. The time it takes will be valued by a quality result. Feel free to leave me a message if you want advice on CAD.