The Ten Commandments (of Modeling and 3D FDM Printing)

Avoid these deadly sins everyone makes in 3D modeling by understanding that 3D printing has some limitations. Here are ten crucial things to remember to ensure your CAD model is 3D printable and your FDM printer provides the best results.

I. Thou shalt limit support material.

3D printing uses support material to hold up parts of your model during the printing process. Support removal may leave marks on your part and increase the likelihood of breaking the piece, so it is best to design your object to need as little support as possible. Angles greater than 45 degrees will require supports.

II. Thou shalt incorporate a flat surface for best results.

A flat surface with no blockages can optimize bed adhesion, achieve a smoother surface finish, and reduce print time and material. The flat surface can be as small as a thumbnail but may need to be larger depending on your object. You can split the model into multiple sections if you do not have a flat surface.

III. Thou shalt meet wall thickness minimums.

Any structurally important walls should be at least 1mm and supported on at least two edges. Hollowed areas need a minimum wall thickness of 1mm as well.

IV. Thou shalt ensure that fine details are printable.

Embossed detail should be at least 2mm high, and engraved details should be at least 0.5mm deep. If incorporating text, it should be at least 1mm wide at any point of a letter and leave at least 1mm between letters.

V. Thou shalt double-check hole size.

The smallest hole you can achieve on most printers is 2mm in diameter. Holes smaller than 2mm may fuse or become heavily deformed during printing.

VI. Thou shalt account for spacing on moveable parts

If you have moveable parts that need to be printed together, each part should be placed at least 0.5mm apart to keep pieces from fusing.

VII. Thou shalt consider sizing tolerances for fitted parts.

Ensure the clearance between interlocking pieces is 0.3mm for a snug fit. Offset them by 0.5mm or more if you connect and disconnect the parts frequently. Also, the more you fit the pieces together and take them apart, the looser the fit will become.

VIII. Thou shalt check printer specifications.

Always check the specifications before you begin modeling. When scaling down models to fit the print bed, recheck that the scaled-down dimensions still follow the design guidelines mentioned earlier.

IX. Thou shalt keep your filament dry.

When you extrude filament that has absorbed water, the water in/on the material vaporizes and creates air bubbles. This can break apart the polymer chains, weakening the material and creating voids in the filament strands, which weakens inter-layer adhesion. It also leaves an undesirable surface finish.

IX. Thou shalt remember to level your bed.

3D printers are created differently, so some machines need the bed leveled more often than others. Some never need leveling and work just fine. It generally depends on several factors, such as how well you assembled the 3D printer and how often you move it. Many people level their bed after 5-10 prints or before doing a really long print to ensure better success. You can reduce the need to level your bed with the correct methods.

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