The sun had just risen, illuminating the workshop of the municipal mechanical technical school. Unlike yesterday's quiet scene with measuring tools, today the workshop was filled with the metallic smell of machines. Dozens of machine tools were neatly arranged, including lathes, milling machines, and drilling machines, with more than twenty C616 lathes alone—the main equipment for today's lathe operator competition.

The contestants were all busy at their workstations, some wiping measuring tools, others testing machine tool handles, even their breathing was heavier than usual. The judges, dressed formally, walked around with their hands behind their backs, their eyes like rulers, making everyone's heart tighten. Liu Li stood in front of the C616 lathe assigned to her. Her blue overalls made her look a little thin, but her eyes were steady and she wasn't flustered at all. She took a deep breath, touched the cool bed frame, and then turned the slide handle. Listening to the soft "click-clack" of the gearbox, the last bit of tension in her heart relaxed—this place was like a factory, she knew it very well, there was nothing to panic about.

"Lathe operators, take your positions!" The head referee blew his whistle, his voice booming. "Competition: Machining of stepped shaft assemblies! The drawings and blanks have been distributed! The competition is about dimensional accuracy, strict geometric tolerances, and a smooth surface. We also need to see how well you work and how quickly you do it! You have three hours! Now—begin!"

As soon as the whistle blew, the workshop erupted in a deafening roar of machine tools, like a boiling pot, so loud it made my ears tingle.

Liu Li didn't rush to turn on the machine; she first picked up the blueprints and flipped through them. This shaft was not simple; it had several outer circles of different thicknesses, as well as relief grooves and chamfers. There was a short conical surface hidden in the middle. The most critical part was that a section had to be kept coaxial, and the tolerances were extremely tight. Most dimensions had to be at IT7 level, and the critical section had to be at IT6 level—not even a slight difference was acceptable.

She quickly went through the process Fu Jingchen had explained in her mind, and then remembered what Master Wang had said, "Think it through before you start." She immediately made up her mind: first, rough turn to remove most of the iron filings and find the benchmark; then semi-finish turn to leave some room for the final fine finishing; and finally, she would focus on the conical surface and the key mating section—these two are the key to winning or losing and cannot be taken lightly.

She selected the cutting tool, mounted the blank on the chuck, aligned it, and tightened it… Her movements were smooth and efficient, without any hesitation. Compared to some of the other competitors who were frantically adjusting their machines, she looked remarkably steady. Once the machine was running, she adjusted the speed and feed rate, gripped the slide handle, and as soon as the cutting tool touched the blank, a large string of bluish iron filings flew out and fell down with a "whoosh." During roughing, she applied even pressure and controlled the depth of cut well, preventing the machine from wobbling—this was what Master Wang had taught her; even roughing requires some leeway, you can't just do it haphazardly.

After roughing, she switched to a semi-finishing tool and began to gradually approach the exact dimensions. Her measuring tools were constantly in motion: calipers for the outer diameter, micrometers for the finer details, taking readings quickly and knowing the difference with a glance. When the tool became a little dull, she stopped and quickly adjusted the cutting edge on the grinding wheel; when the cutting heat caused the workpiece to swell slightly, she waited for it to cool before measuring again—these details were honed through practice, leaving no room for error.

Time flew by, the buzzing sound in the workshop never stopped. Some of the workers were sweating profusely, either because the dimensions were wrong and they had to rework, or because they hadn't chosen the right tool and the finished surface was rough. Next to Liu Li was a burly man, supposedly from the city's mining machinery factory. He worked quickly and efficiently, producing shafts so smooth they reflected a person's image. He seemed to notice her looking over, glancing at her with a "can you handle this?" look in his eyes, a hint of defiance in his gaze.

Liu Li ignored him, remembering Master Wang's words: "Don't worry about how fast others are, just focus on accuracy." She concentrated all her attention on the short conical surface, first gently cutting a small section, checking it with a universal angle gauge, then applying some red lead to the surface, aligning it with the standard block, and only after confirming the contact point was even did she begin the precision machining. The tool tip gently brushed against the workpiece, curling up fine, hair-like silvery iron filings, and the conical surface slowly became smooth, even the tool marks were no longer visible.

When tackling that crucial final section, she switched to a finely sharpened cutter, slowed the spindle speed, and reduced the feed rate to an extremely small amount, almost like embroidery. She stopped after each revolution of the machine, measured with a micrometer, and made minor adjustments to the slide if it was even half a millimeter off. Her palms were sweating, but she didn't dare relax—if this section went wrong, all the previous work would be wasted.

After finishing the last cut, she gently removed the burrs with a fine oilstone, took the axle off the chuck, and placed it on a tray lined with cotton gauze. Looking up at the clock on the wall, there were still more than twenty minutes until the appointed time.

The judges began inspecting each workpiece one by one, their measuring tools a motley collection, including lever micrometers and roundness testers. When they measured Liu Li's shaft, the judges examined it with particular care. An older judge measured it again and again with a micrometer, reciting, "Diameter 25 mm, tolerance 15 microns, within tolerance! Roundness 0.002 mm, runout 0.005 mm—good!" Several judges nearby exchanged glances and nodded in agreement.

The man from the mining machinery factory was also quite good at his job, but when it came to measuring the roundness of the critical section, he was off by 0.001 millimeters, which was slightly inferior to Liu Li's.

Liu Li breathed a sigh of relief, and her shoulders relaxed a bit more—the skills she had practiced and the theories she had memorized over the past few days had finally paid off, and she had put them all into this shaft.

The lathe competition was over, but Liu Li didn't rest. There was a fitter competition that afternoon, her specialty, and the real challenge. She packed up her tool bag, took a deep breath, and her eyes were already on the fitter's workstation—now, she had to show her true skills.