For this assignment we had to 3D print a part that would be infeasible to make using any other process.

I have seen videos on YouTube where people use a metal lathe to turn bolts with heads at both ends, and they “magically” (by cheating) get a nut onto the middle. They look like this:

While browsing Thingiverse, I found this post about a way to 3D print a similar object. The difference is that with a 3D printer, you can actually make the bolt one single, solid piece. I know of no (practical) way to do this using any other fabrication method. Given the shape of the piece I wanted, using an FDM printer seemed appropriate.

To make the part I simply downloaded the file from the website, then imported it into the 3D printer software. Then I selected the side I wanted as the base, made sure that no support material would be generated, then started printing.

At first I just printed one test piece and stopped it half way through, just so that I could make sure that the nut would fit on properly. The fit was good, so I continued on.

To make this work I printed 2 of the bolts and spaced them on opposite sides of the printer platform, so that when the extruder was printing one of them, the other would be unobstructed.

Halfway through the print, I paused the printer and threaded a metal nut onto the unobstructed bolt. I then resumed the print and did the same for the other side.

Because no support material was generated, there was a slight problem printing the top part of the bolt. The melted plastic drooped and sagged a bit, so the shape was not as well defined as the bottom.

Additionally, because the shape was so tall and the base was so small (Sid Richardson college), it was pretty unstable. Near the end of the print, both shapes ended up getting knocked over by the extruder.

I think if I were to have the opportunity to do it again I would try including a “raft” to make the base wider so that it would not fall over. I think the top would look a lot better if the print had been able to finish completely. Fortunately this happened with only a few minutes left in the print, so it was not a big deal. The parts still turned out pretty well.

For post processing, all I had to do was clean them up a bit. I used scissors to cut away the strands of plastic that were attached to various parts of the bolts. In some places it was very difficult to turn the nut, so I used a pair of pliers to grip it and I wrapped a lanyard around the threads to get a better grip on them, then I carefully turned the nut all the way back and forth a few times to straighten out the threads. Now the nut moves smoothly across the bolts.

This was my first time 3D printing something, and overall I am super impressed.