Digital technologies/3D printing/3D printing- Beginner/What not to print
Supports are one of the most significant contributors of the quality of your print, for better or worse. Since 3D printers cannot defy gravity, most models with any geometry suspended in mid-air will require some form of support structure to ensure a successful print. However, since support structures will make contact with your model, surface scars will form at these points of contact, and enabling supports for a print that does not require them will lead to worse quality for no benefit. Using supports when they aren't necessary also leads to wasted plastic, and more time wasted removing them afterwards. Thus, being able to recognize when supports AREN'T required, and knowing what settings to use if they ARE required are essential skills for a 3D printing enthusiast!
Overhangs
Imagine 3D printing the capital letter "T" in an upright orientation. This would be referred to as an "overhang," as a portion of the "T" overhangs from either the left or right sides of the letter. Since the 3D printer isn't capable of laying down flat and even layers of plastic in midair, this print would most likely fail or result in "stringy" quality on the overhanging surfaces. A "T-Overhang" would be an example of an overhang that would require the use of supports.
However, not all overhangs require supports, imagine 3D printing the capital letter "Y" in an upright orientation. This would also be referred to as an overhang, since the top of the "Y" will overhang from either the left or right sides. One may think because of the overhangs, supports would be required, however, printing the "Y" without any supports would result in a successful print. Since the overhanging portions of the "Y" gradually slope upwards, and the 3D printers operate on a layer-by-layer basis, each layer of the "overhanging portion" will be supported by the previous layer. These overhanging portions are often described with the term "overhang angle", and an overhang angle of less than 45° is usually safe to print without supports. Since the "T" has an overhang angle of 90° with the vertical, it would be considered unsafe to print without supports.
Therefore, when designing models for 3D printing, avoid "T" style overhangs, and use overhanging angles of 45° (or less) as much as possible. If you're printing a model with overhangs, try to re-orient it to minimize the amount of "T" style overhangs. For example, orienting the letter "T" so that it lays flat on the bed ensures that supports will not be required.
Bridges
Bridges are overhanging sections that are supported by two or more model sections (e.g.: the middle section of an H is a bridge). It can be possible to print bridges without the use of supports, though one should take care to optimize their printer settings (lower temperature, higher fan speed, etc.) to limit drool. Tuning a printer or adapting a slice for bridging demands a deep understanding of the fundamentals, and such, these will only be discussed in a more advanced 3D printing learning module.
Removing Supports
Removal of supports can also determine if one wants to use them. In prints using larger nozzle sizes (hotter nozzle, higher material flow), supports might be firmly fused to the model being printed. In such cases, removing supports might be extremely difficult. However, when using optimal settings, supports will be easy to remove. They typically break off with little effort. A pair of small long nose pliers can also come in very handy when removing supports.