3D printers often have as many limitations and design guidelines as other manufacturing methods. This project is a mockup for a Gas-powered power plant, divided into three design stages: the boiler, gas tank, and turbine station. Each component was designed using "design for 3D-printing" concepts, allowing for easy printing without additional support materials. 

Many thanks to Creatables-3D for hosting this project and providing the necessary materials and machines. Their support was instrumental in bringing this idea to life. 

Bridging

Bridging in 3D printing refers to the printer's ability to create structures between two points without the need for support material. It is generally not recommended to have gaps or bridges exceeding 15mm in a design. Larger gaps can cause sagging in the lower part of the bridge unless support material is added. It is preferred to reduce the gap size rather than relying on support material, as the latter can affect the surface quality where it touches the part. 

P.S. It's worth mentioning that bridges connect two points at the same height with a straight line, while any gap connecting points at different heights is considered an overhang. 

Overhanging

FDM 3D printers build objects by layering plastic, but printing in mid-air is not possible. To address this, you have two options: carefully design your object to control overhangs or utilize support material. Overhangs with angles up to 45º typically print with high quality. With certain factors like material, layer height, and printer capabilities, you might achieve decent-quality prints with overhangs up to 60º. However, it's advisable to use support material for overhangs exceeding 60º. 

Vertical holes

In FDM 3D printing, it's common to encounter undersized vertical holes. This issue arises due to the nature of the manufacturing process, where the extruded plastic gets compressed against the previous layer, resulting in smaller-than-expected holes.

To address this, it's recommended to conduct tests to determine the extent of undersizing and adjust the design accordingly. For instance, if you require a 2mm hole, adding an offset of approximately 0.2mm to 0.4mm to compensate for a tight fit may be necessary.

Interlocking parts tolerances

If the 3D model consists of interlocking parts, it's important to apply an offset to the hole parts ranging from 0.2mm to 0.3mm between them to ensure easy assembly. The exact offset value will depend on how loose or tight you want the mating to be.

Printing Orientation

3D printed parts tend to have weaker strength in the direction perpendicular to the layers. This is due to the layer adhesion, which affects how well the layers bond together. When printing functional parts, it's crucial to consider the part orientation during the slicing process.

To enhance strength, it's advisable to orient the part in a way that maximizes the surface area of each layer. For instance, if you have a long part that needs to withstand weight, printing it with layer lines perpendicular to the weight direction can improve its strength.

Warping

Sharp corners in 3D-printed objects can lead to stress concentrations, which often contribute to warping issues. However, by adding fillets or rounded edges to these corners, the stress concentrations can be reduced. The rounding effect helps distribute the stress more evenly.

To minimize warping, it is generally recommended to design cross sections with a more rounded shape where they come into contact with the build plate. This promotes better adhesion and reduces the likelihood of warping occurring during the printing process.

Fillets

To enhance the strength of specific areas in a 3D model, incorporating fillets is a straightforward solution. This approach is particularly valuable for reinforcing delicate components that connect to the main body. By adding a simple fillet, you can strengthen the part and mitigate stress concentrations. 

Modifying Geometries for 3D Printing

Pipes, Spheres, and Complex Models sometimes need modifications to be 3D-printable and follow the 3D Printing restrictions and machines' capabilities. Starting with pipes, in this model thin and long pipes were required to represent the water pipes in real life. If they were printed standing, the printing time would be too long and the part itself would be fragile. On the other hand, printing them lying on the bed of the machine would cause stability issues due to minimal contact area.

Modification: cutting part of the circular profile to obtain a flat surface for better surface adhesion.

Second, Spheres. For the same reasons as pipes, spheres are impossible to print due to their very small footprint and massive overhang angle.

Modification: cutting part of the spherical profile to obtain a flat surface for better surface adhesion.

Finally, Complex Models. A complex model has no definite shape or geometry, it could look like anything. However, we can define a complex shape as a part that if printed as one piece will need support. OR, it's too large for the printing volume of the printer. In this case, this part needs a parting process to cut it into pieces that are 3D-printable. But, the question will always be, how these parts will unite together again.

Modification: Adding alignment pins to adjust the parts so that they connect with any misalignments.