3D printing threads

In recent years 3D printing has caught the mainstream eye, becoming the new buzzword of technological innovation, with 3D printing DIY tutorials gaining millions of YouTube views. People are fascinated by the idea of creating customized products in a relatively short time. 3D printing is manufacturing 3-Dimensional objects layer by layer using a Computer-Aided Design model (CAD). This definition of 3D printing is very simplistic. In reality, 3D printing is a complex process with multiple steps. The printing part is only the last step in the entire workflow.

Although 3D printing has applications in a variety of fields, for an engineer 3D printing is a dream come true. Effectively changing the prototyping process. Instead of waiting for the manufacturer to produce the parts, the engineer can rapidly make a prototype of his own. Then do the relevant experiments and subsequent changes to the design if needed. In this essay, we will be discussing the printing process. This will be done using a case study of internal threads of a cap and the effect of the associated clearance.

In this experiment, we had to print a cap for a hand sanitizer bottle. At first glance, this seems like a relatively easy task. Just measure the external diameter of the bottle and make that the internal diameter of the cap. However, there was a big problem with this method. I had not accounted for the clearance between the threads. But before we get into clearance let’s first talk about the helical sweep and proper printing settings required for making threads.

The MakerBot Debacle

Initially, we tried printing the cap using the MakerBot. However, there was a problem with the printer. Although the technicians would be better suited to diagnose the problem, I believe there was a problem with the gears that abled the extruder to move on the XY plane. I say this because the height of the cap was nearly accurate. However, the finished product had more of a squarish shape than a cylindrical.

The first 3D print attempt failed miserably with the filament detaching from the extruder.

This was the second attempt on MakerBot. As you can see the shape of the cap is not cylindrical.

Supporting the Local

Following the disappointing attempt on MakerBot, we decided to use a locally produced printer, OBJEXYZ. The finish on the objects printed with this was far superior to that of the MakerBot (probably because OBJEXYZ was a relatively new printer). The printed cap looked good, but aesthetics was the only thing going for it. The handedness of the cap was left-handed instead of right, and the internal diameter was too small. This was when I realized that I had not accounted for the clearance between the threads.

The first print using the OBJEXYZ printer.
Problems: Wrong handedness orientation and too tight.

Then I made changes to the CAD design. Fixed the handedness and increased the clearance to 2 mm. However, 2 mm clearance was too much, making the cap loose. So once again, I had to change the inner diameter to change the clearance. The diametric clearance I decided to go with was 0.6 mm. This was the perfect fit for the hand sanitizer bottle.

The one with 2 mm clearance.

This print was called Potentially last because I had changed the clearance and everything seemed right. Alas, it was not meant to be. The printer had a malfunction because of which (as seen in the picture) the quality of the product was ruined.

This was named hopefully last because at this point the only thing I had left was hope that this print would succeed

Progression of the caps