How to 3D print unbreakable threads

When it comes to making objects with an additive printer, the obvious or assumed natural part orientation is not always the best choice. Here’s a good example of thinking about part orientation differently.

When Zack Slezak, engineering intern at 3D Platform, needed to create a bracket for a filament sensor for an additive manufacturing printer, the use of an additive manufacturing printer seemed a natural fit.

The filament sensors tell the additive machines when the material is about to run out, and when the printer should pause printing to reload the filament.

The bracket would have to hold the filament sensor and be mountable on the additive machine. Slezak’s design included two filament tubes screwed into the top of the bracket. At first he chose to use PLA as the material for the bracket. However, the bracket would crack every time he threaded the hole for the filament tube.

His solution was to redesign the holes in the top with thicker walls surrounding them. This solution helped, but the bracket still cracked. Next, Slezak changed the way the part was oriented for the build.

Initially Slezak thought it would be best to build the bracket on its back, which would allow the part to print faster. But printing it this way affected the layering, which allowed the tips of the holes to pop off under pressure, in particular when threading the holes.

Thickening the walls around the hole and changing the direction of the print gave the part the ability to withstand the threading without cracking.

Better print direction:

The following photo shows how the part held during the threading process:

And after threading:

Here’s what the finished product looks like:

Additively building a part on its side, as shown in this example, may seem a bit counterintuitive. It can increase the build time. But the final part orientation decision rests on what properties does the part need to have? In this case, strength was more important than build speed.

Photos courtesy of 3D Platform.