The day started like any other: arriving at the company, clocking in, changing into work clothes, and heading to the maintenance department. Since Jorge had his own work to do, Žak and I were forced to work with Juan. Our task was to use a lathe to manufacture a custom-sized nut with a 1.5mm pitch.
We went to the first-floor warehouse to find a suitable piece of iron. After a few minutes, Juan found a nut. The plan was to enlarge the hole and cut a new thread, but we couldn’t use it because it wasn’t stainless steel (inox). We had to keep looking. Eventually, we found a suitable bolt to repurpose. We needed to remove the thread to leave only the head, which would become the nut. I assumed Juan would use a proper cutting tool on the lathe, but he wanted to be “special”-he used an angle grinder to cut the thread off instead. He ended up having to face the head on the lathe anyway, a step he could have avoided if he had used the right tool from the start to get a clean surface.
Then he started drilling the hole into the bolt head without using any coolant. When I mentioned it, he dismissed it, saying it didn’t matter. Jorge took us to lunch while Juan stayed behind to keep drilling. When we returned, we found him sharpening a drill bit. He did it incorrectly, so he had to flatten the edge and start over. He eventually drilled a 15mm hole, but since we needed a 25mm and couldn’t find a larger bit, Juan decided to enlarge it using a boring bar.
His initial idea to use a threading tool for boring was frankly stupid. When the tool holder proved too large, he had the “brilliant” idea of making his own. He took a smaller turning tool and hand-ground it into a 60° threading tool. I told him it wouldn’t work, but he insisted. Once he saw that his “monstrosity” was useless, he finally listened and simply ground down the holder of the original tool to make it fit.
He finally started boring the hole to 25mm. When he reached 24mm, I warned him to be careful, but he confidently told me not to worry. In the end, he oversized it to 26mm-a total failure. He decided to practice the threading anyway. He tried using ChatGPT to set the lathe parameters for a 1.5mm pitch, but it was useless. I checked the settings and found several errors: for one of them, he kept arguing with me even though he was clearly wrong.
The lathe wouldn’t engage in automatic mode, so he called a colleague. The colleague noticed the same error I had pointed out, along with a lever that wasn’t fully engaged. Once that was fixed, Juan started arguing that both the X and Z axes should move during threading, which is incorrect. The colleague had to come back to explain that only the Z-axis moves. When Juan finally started, he complained the Z-axis was moving too fast, not realizing that the Z-feed is directly linked to the spindle RPM. After I explained the ratio to him, he lowered the RPM and finally cut the thread. The workday was finally over, and Žak and I headed back to the apartment.
