If you’ve got a 3D printer, it can be easy to think that you can print anything. Some parts require more planning and careful design than others, though. There are also applications for which 3D printing can struggle, at least with common materials and processes. One of these applications is threaded parts. When talking about threaded parts, most people will think of screws or nuts and bolts. These are the most common but far from the only uses for threading with other applications, including worm gears and linear drives.
Unfortunately, 3D printing threaded parts can be difficult if you’re trying to create small parts. This is because the size of the threads in many applications is tiny. It can be difficult to reliably recreate a small thread because layer heights and tolerances of a 3D printer can be significant compared to the size of the fine details.
Another difficulty you can face is simply the strength of the printed parts. The fine detailing on 3D printables can often be quite weak and brittle. For threaded parts, this detailing is also an overhang, albeit a small one. The stresses applied to the threading are also aligned with their weakest dimension. Unfortunately, this tends to make 3D printed threaded parts useless from a functional perspective. The only way to avoid this is to print at a large size or use more exotic methods and materials with much greater strength than common plastics.
Allowing for the Difficulties
If you decide to print threaded parts, it’s important to ensure that the interior and exterior threaded parts fit together. Before committing to a large-scale piece, it’s best to test that the threaded parts will fit together by printing just the threaded parts of the model to scale.
It’s important to allow for your printer’s tolerances, or dimensional accuracy. You can’t rely on both the interior and exterior threaded parts fitting together perfectly. It would help if you made the interior threaded part slightly larger to allow for the inconsistencies of the printed material. It’s also important to remember that most 3D printing materials contract as they cool, which can also throw off your careful scaling. Try to avoid materials known for thermal contraction issues such as warping, such as ABS and nylon.
Print with the smallest layer heights you can for the best results. As the thread is a slope in the Z-axis, it can end up with a stair-stepped effect making it useless if your layer height is too large. It’s also important to consider cooling. Interior threads in a large print may not need much cooling as the hot print head will move away, allowing it to cool naturally. Exterior threads, however, will likely have the print head stay in close proximity, so active cooling is recommended.
Printing threaded parts is a cool use for a 3D printer. Still, there are many potential pitfalls, and the results are often weak and unsuitable for functional pieces. If you’ve got any other tips to share regarding 3D printing threaded parts, let us know down below.