Eight-year-old Nangong Wentian was awakened by a clamorous noise.
It wasn't the usual kind of sound—not the commotion of children getting up, nor the chanting of the nuns during morning prayers, but… a rhythmic, dull thudding.
Thump. Thump. Thump.
He opened his eyes. Outside the window, the sky was just beginning to brighten. In the bed next to him, Xiao Guang was still fast asleep, a trace of drool at the corner of his mouth.
Thump. Thump. Thump.
The sound was coming from the courtyard. Nangong Wentian quietly got up, threw on his coat, and slipped out of the dormitory.
In the courtyard, Sister Mary was bent over a large basin, vigorously pounding something. Beside her was a mountain of clothes—bed sheets, duvet covers, the children's dirty laundry.
Thump. Thump. Thump.
It was the sound of a wooden mallet beating against the clothes.
"Sister Mary?" Nangong Wentian walked over. "What are you doing?"
Mary looked up, her forehead beaded with sweat, a weary smile on her face. "Washing clothes. The washing machine is broken, so I have to do it by hand."
Nangong Wentian looked at the large basin. Several bed sheets were soaking inside, the water already murky and gray. Mary's hands were immersed in the water, bright red.
"The washing machine is broken?" he asked.
"Yes," Mary sighed. "It was fine yesterday, but this morning it just wouldn't spin. Sister Agnes fiddled with it for a long time but couldn't fix it."
Nangong Wentian was silent for a moment, then said, "Can I take a look?"
Mary was taken aback, looking at the eight-year-old child before her. She knew this child was somewhat special—after the incident with the power supply system being repaired last time, the head nun hadn't explicitly said so, but she had a vague suspicion that this child had done it.
"You know how to fix a washing machine?" she asked.
Nangong Wentian thought for a moment and answered honestly, "I don't know, but I can try."
Mary studied him for a while, then nodded. "Go ahead, it's in the storage room."
Nangong Wentian turned and ran toward the storage room.
It was a cramped little room, piled high with all sorts of odds and ends—broken chairs and tables, rusty tools, dusty boxes. In the corner stood an old washing machine, lonely and forlorn, its door open and empty inside.
Sister Agnes was squatting beside it, holding a screwdriver and staring blankly at the control panel. Seeing Nangong Wentian enter, she looked up and asked, puzzled, "What are you doing here?"
"Sister Mary asked me to take a look," Nangong Wentian said.
Sister Agnes was momentarily stunned, then gave a bitter smile. "What's a child going to look at? This is a machine, not a toy."
Nangong Wentian didn't argue. He simply walked over, squatted down, and carefully examined the washing machine.
It was a very old-style pulsator washing machine. The casing was already covered in rust, several buttons on the control panel were missing, and the exposed wires were wrapped with tape. He reached out and shook the washing tub, feeling the looseness inside.
"Try turning it on?" he asked.
Sister Agnes hesitated for a moment but still plugged it in. Pressing the start button, the washing machine emitted a low hum, and then… nothing happened.
"See," Sister Agnes sighed. "It just won't move."
Nangong Wentian turned off the power and began to examine carefully. His gaze swept over every component—the motor, belts, control panel, wiring...
"Can I take it apart?" he asked.
Sister Agnes widened her eyes. "Take it apart?"
"Yes, to see inside."
"Will you be able to put it back together?"
Nangong Wentian thought for a moment. "I should be able to."
Sister Agnes looked at him with a complicated expression. An eight-year-old child saying he wanted to take apart a washing machine and claiming he "should be able to" put it back together—if it were anyone else, she would have thought he was fooling around. But remembering the incident with the power system last time...
"I'll go ask Mary," she said, standing up and quickly leaving the storage room.
Nangong Wentian didn't wait and started right away.
He found a screwdriver from the corner and began removing the washing machine's back cover. The screws were rusted and difficult to turn, but he gritted his teeth and twisted them bit by bit.
A few minutes later, the back cover came off. The internal structure was revealed—the motor, pulley, reducer, drain pump... and a complex set of transmission mechanisms.
Nangong Wentian carefully examined the gears. Soon, he found the problem—several gear teeth were worn almost flat, especially on the largest reduction gear, where several teeth were completely missing.
"Gear wear," he said silently to himself.
But just looking wasn't enough. He needed more precise analysis.
He ran back to the kitchen and took out the portable terminal of the "Star Core" from the broken wooden crate—a small tablet cobbled together from scrap parts, with a screen only the size of a palm and a cracked frame. He also grabbed a small box containing a simple measuring tool he had recently made: a displacement sensor modified from an old mouse wheel, along with a few resistors and capacitors, which could roughly measure gear dimensions.
Returning to the storage room, Sister Agnes hadn't come back yet. Nangong Wentian seized the opportunity and began measuring.
He first used a ruler to measure the approximate dimensions of the gears—diameter, thickness, number of teeth. Then, using the simple sensor, he measured the tooth profile—crude, of course, but better than nothing.
He recorded the data one by one in his notebook:
Reduction gear: diameter 86mm, thickness 12mm, 42 teeth, most severely worn, three teeth completely missing, remaining teeth worn by about 30%
Intermediate gear: diameter 54mm, thickness 10mm, 26 teeth, lightly worn, about 10%
Motor gear: diameter 32mm, thickness 10mm, 15 teeth, minimal wear
...
Just as he recorded the last piece of data, Sister Agnes returned, followed by Mary.
"You really want to take it apart?" Mary asked.
Nangong Wentian nodded. "Found the problem. The gears are broken. Need new ones."
Mary frowned. "Replace the gears? Where would we find parts for such an old machine?"
Nangong Wentian fell silent for a moment, then said, "Maybe we don't need new ones."
Both of them were stunned. "What do you mean?"
"We can repair it," Nangong Wentian pointed at the worn gear. "We can rebuild the missing teeth."
Sister Agnes opened her mouth, about to say "How is that possible?" but swallowed the words. Looking at this eight-year-old child, she suddenly felt that maybe it really was possible.
That night, after everyone had fallen asleep, Nangong Wentian took the broken gear and slipped into the kitchen.
He activated the Star Core and called up the gear analysis module. This was a recently perfected function—he had input the basic formulas of UC Era mechanical design and added parameters for materials commonly found in the SEED World. Now, the Star Core could perform simple mechanical analyses.
He entered the measured data one by one.
The cursor on the screen blinked for a long time—the rudimentary CPU's processing speed was still painfully slow. Nangong Wentian waited a full ten minutes before the results appeared.
Gear Parameters:
Module: 2.0
Pressure Angle: 20°
Tooth Profile: Involute
Material: Ordinary Carbon Steel
Wear Analysis:
Original tooth profile data reconstructed
Missing tooth position: Tooth 23
Stress analysis indicates: This position bears the maximum torque; severe wear is inevitable
He stared at the three-dimensional model on the screen and began considering repair options.
The simplest method was to grind a tooth from a metal sheet and weld it into place. However, this required extremely high precision—any slight deviation in the tooth profile would lead to poor meshing or even jamming.
He needed precise tooth profile data.
"Star Core," he silently thought, "calculate the standard involute profile for Tooth 23."
The screen began displaying the calculation results: a perfect involute curve, densely marked with coordinate points.
He copied these coordinate points one by one onto a sheet of paper.
Then, he rummaged through the clutter in the back kitchen and found a scrap piece of iron—salvaged from a junkyard earlier, its thickness was similar to the gear, and its material was also ordinary carbon steel.
Next, he had to "create" this tooth.
He used a small hacksaw to cut the iron sheet into the rough shape of a tooth, then meticulously filed it down bit by bit. Every few strokes, he measured the dimensions with calipers, comparing them to the coordinates on the paper.
It was an incredibly tedious process. A single tooth required over a dozen coordinate points, each needing precision down to fractions of a millimeter. Filing even slightly too much would ruin the entire tooth.
But Nangong Wentian was patient. He filed away, stroke by stroke, his eyes fixed on the tiny tooth as if nothing else in the world mattered.
After what felt like an eternity, the sky outside began to lighten. He finally filed the first tooth that matched the coordinates.
He placed the small tooth against the missing spot on the gear and compared—it fit perfectly.
Next came welding.
He took out the soldering iron and found a small piece of solder. However, ordinary solder wasn't strong enough—the gear bore significant force, and it would detach before long. He needed a more robust connection method.
He recalled seeing a small roll of copper brazing rods at Yamada's place. If only he could use oxy-acetylene welding…
But he didn't have oxy-acetylene welding equipment.
So, he resorted to the simplest method—drilling holes and securing it with rivets.
Using an old drill bit, he drilled two small holes in the missing position on the gear and corresponding holes in the newly filed tooth. Then, he threaded two short pieces of iron wire through the holes to fix the tooth to the gear, hammering the ends of the wires flat to form rivets.
While this connection wasn't as strong as welding, it would at least work.
By the time he finished, the sky was fully bright.
The next evening, Nangong Wentian reinstalled the repaired gear into the washing machine.
Xiao Guang watched nervously from the side, hardly daring to breathe. He had heard about the repair during the day and insisted on coming to help in the evening.
"Will it work?" he whispered.
Nangong Wentian didn't answer. He installed the pulley, tightened the last screw, then said to Sister Agnes, "We can try turning it on now."
Sister Agnes took a deep breath, plugged in the cord, and pressed the start button.
The washing machine emitted a low hum, and the drum began to turn—slowly at first, then faster and more steadily.
"It's turning!" Xiao Guang was the first to jump up. "It's turning, it's turning!"
Sister Agnes stared wide-eyed at the spinning washing machine, speechless for a long moment.
Sister Mary stood at the doorway, watching the scene with a complicated look in her eyes.
Nangong Wentian stared at the rotating drum, silently calculating in his mind. The sound of the gears meshing was smooth, without any unusual noise, indicating that the hand-filed teeth basically met the requirements.
"Alright," he said to Sister Agnes, "it should be usable now."
Sister Agnes crouched down, looking at this eight-year-old child covered in sweat, and suddenly reached out to pat his head. "Child, how are you so capable?"
Nangong Wentian smiled but didn't answer.
Xiao Guang chimed in eagerly beside him, "Wentian can do anything! Last time, that bowl, and that electric..."
"Xiao Guang," Nangong Wentian cut him off.
Xiao Guang quickly covered his mouth.
Sister Mary watched all this and sighed softly. She walked over and said to Nangong Wentian, "Go to sleep. You have to wake up early tomorrow."
Nangong Wentian nodded and led Xiao Guang out of the storage room.
At the doorway, he suddenly turned back and said to Mary, "That gear probably won't last long. If you can find a new one, it would be better to replace it."
Mary nodded. "I understand."
Back in the dormitory, Xiao Guang was too excited to sleep and kept talking about the day's events. "Wentian, you're amazing! Did you file that gear yourself? How did you know to file it like that?"
Nangong Wentian lay flat on his back, gazing at the ceiling, and said softly, "Calculated it."
"Calculated it?" Xiao Guang scratched his head. "How?"
Nangong Wentian thought for a moment and said, "I'll teach you later."
Xiao Guang's eyes lit up. "Really?"
"Mhm."
Outside the window, moonlight streamed into the dormitory. Nangong Wentian closed his eyes, and the data from the day flashed through his mind—gear tooth coordinates, involute equations, stress distribution diagrams...
The Star Core was becoming more and more useful.
For now, it seemed he not only had an "external brain" but also a pair of "hands" capable of turning craftsmanship into reality.
And those hands belonged to an eight-year-old child.