I started with a ship full of max-level veterans, and I'm just a complete noob.

Three days later, it was drizzling at the Fengtai marshalling yard in the early morning.

The military train carrying copper arrived fifteen minutes earlier than the time stated in the telegram. Director Wang and his men guarded the side line of the platform, while Jiang Ming and Fang Xudong were only responsible for checking the seals and counting the box numbers.

The two tons of oxygen-free copper were transferred directly from the military train to the factory's trucks without entering the warehouse.

As the car drove out of Fengtai, Jiang Ming glanced back at the row of wet freight sheds at the end of the platform, but said nothing.

Nine o'clock in the morning, in the confidential cubicle at the south end of the Third Electronics Factory.

Jiang Ming squatted on the ground and used a crowbar to pry open the seal on the last wooden box.

The sawdust and shavings were turned over, revealing two rows of neatly stacked copper ingots underneath.

Each copper ingot was wrapped in oiled paper, then wrapped in a layer of moisture-proof waxed cloth, and had a delivery label from Shenyang Copper Processing Plant affixed to its surface, dated three days prior.

Old Sun handed over a clean piece of cotton yarn. Jiang Ming took it, wiped the wax residue off his hands, and took out the first copper ingot, placing it on the worktable.

When the oil paper was peeled off, the cross-section of the copper ingot shone with a warm rose-red hue under the fluorescent light, completely different from the ordinary yellowish-black copper commonly seen in the workshop.

Old Sun came closer, scratched the edge of the copper ingot with his fingernail, and then rubbed the crumbs with his fingertip.

"This copper has excellent ductility; it's completely different from the stuff we get in our foundry."

Da Liu pried open the second box as well, and turned to shout to Lao Sun, "Master, the two boxes contain a total of forty-eight pieces, not a single one is missing."

Jiang Ming checked off each item on the receiving slip, signed it, and then put the slip into the document folder.

The problem with the copper ingots has been solved, but the next problem is already on the table.

The anode processing drawing that Fang Xudong left on the table yesterday is still spread out in the middle of the long table.

The cross-sectional structure of the eight sector resonant cavities is clearly drawn. The radial depth of each cavity is 8.15 to 8.20 mm, and the slit width is 2.05 to 2.10 mm. The accuracy requirement is marked in the lower right corner, ±0.02 mm.

Old Sun had clearly looked at this blueprint more than once.

He tossed the cotton yarn onto the toolbox lid, walked to the table, and stared at the eight fan-shaped cavities for a long time, his hands resting on the edge of the table.

"Jiang, I've been thinking about this all night, but I still can't figure it out."

Jiang Ming walked over and stood next to him, waiting for him to continue.

"Eight cavities, symmetrically distributed, with each cavity having the same radial depth and slit width, and the deviation cannot exceed two."

Old Sun used his thumbnail to trace the width of the seam on the paper.

"If there were a dedicated multi-blade forming milling cutter, it could form eight cavities simultaneously in one cut, with the precision guaranteed by the cutter itself, which would be the most convenient option."

"But we don't have this knife."

Jiang Ming nodded, "No one in China has ever made this kind of knife before. Custom-made would take at least three months, and it's hard to say whether the precision will meet the standards."

"What if we use a regular milling cutter to mill each cavity one by one?" Da Liu interjected from the side.

Old Sun shook his head. "After the first cavity is milled, the workpiece is repositioned to mill the second one. The indexing error alone can eat up half of the allowance."

"After milling eight cavities, the accumulated error can reach five or six or even more. At that point, the resonant frequencies of all eight cavities will be scattered, and the tube will be scrap copper."

Da Liu fell silent and stepped aside to continue counting the copper ingots.

The workshop was quiet for a while, with only muffled sounds coming from the distant foundry workshop.

Jiang Ming turned around and walked to the old C620 lathe in the corner. He reached out and touched the edge of the chuck, his fingers tracing a circle around the graduation marks.

Last night, during my psychic communication with Kozlov, after explaining the hot-brittle correction formula, he also mentioned a geometric processing approach.

Back in the day, there was an old fitter in the Leningrad factory who, lacking specialized milling cutters, once used an eccentric positioning method to machine a similar multi-cavity structure on a lathe.

Kozlov only provided the direction, without going into detail about the specific parameters, but Jiang Ming had already figured out the core logic of that geometric transformation.

"Old Sun, come and take a look."

Old Sun walked over, his hands still covered in oil stains from handling the copper ingots.

Jiang Ming pulled a piece of white paper from under the workbench, laid it on the metal tool cabinet next to the lathe, and drew a circle with a pencil.

"The copper billet is cylindrical, with a diameter two millimeters larger than the outer diameter of the anode, leaving a margin, and is fixed on the indexing plate."

He added another dot next to the center of the circle.

"The key is that the geometric center of the billet does not coincide with the rotation center of the indexing plate; it must be offset by a calculated distance."

Old Sun frowned and leaned closer to examine the distance between the two points.

"Off-center positioning?"

"Yes, the eccentricity is calculated based on the radial depth of the cavity and the inner diameter of the anode. I calculated it last night, and it is about 3.72 millimeters."

Jiang Ming marked the numbers on the paper and then drew the second step.

"After the billet is eccentrically fixed, use a regular lathe tool to machine a through hole, the diameter of which corresponds to the inner diameter of the cathode area."

"With this cut, due to the eccentricity, the hole produced is not in the exact center of the blank, but off to one side."

"And then?" Old Sun had grasped the idea, and his eyes lit up.

"Then rotate the dial forty-five degrees and cut another hole of the same diameter."

"The second hole will overlap with the first hole in a certain area. The crescent-shaped gap formed by the overlap is the prototype of a resonant cavity."

Jiang Ming drew two intersecting circles on the paper and used a pencil to black out the overlapping area.

"Eight chambers means that the scale rotates eight times, forty-five degrees each time, to machine eight holes."

"The eight crescent-shaped overlapping regions are the rough prototypes of the eight resonant cavities."

Old Sun grabbed the pencil and drew it on the paper. After finishing, he stared at it for about ten seconds.

"wonderful."

"The accuracy is entirely guaranteed by the indexing plate, which has an accuracy of a few ten-thousandths, making it much more reliable than the indexing of the milling cutter."

He slapped the pencil onto the paper.

"The remaining work is the connection between the two ends of the crescent-shaped cavity. The lathe tool can't cut a right angle, so we have to manually scrape and grind to adjust the excess material to the correct position."

"Yes, that part is your job."

Old Sun rubbed his hands together, turned to Da Liu and shouted, "Da Liu, go to the tool room and get that imported indexing plate. It's the one we salvaged from a scrapped Soviet milling machine last year, the one with worm gear drive."

Da Liu responded and ran off.

Old Sun turned to look at Jiang Ming, a rare hint of excitement on his lips, but what he said took a different turn.

"Jiang Gong, this method is brilliant."

"The addition of an eccentricity and an indexing plate completely bypasses the problem of specialized cutting tools."

He picked up a piece of cotton and wiped the oil off his hands, lowering his voice by half a notch.

"If Lei had known this technique back then, his radar's resonant cavity wouldn't have been criticized by Soviet experts for not being precise enough, forcing them to import parts from Moscow."

Jiang Ming paused for a moment, his pencil still in his hand.

Old Lei.

He had heard this name several times.

It always comes from different people, and it always comes with an indescribable tone.

But he never asked.

"Let's go, let's first adjust the three-jaw chuck's runout to within two levels."

Old Sun had already turned and walked towards the lathe, as if his previous remark was just a casual remark.

"Before installing the indexing plate, we need to check the worm gear clearance first."

Jiang Ming folded the sketch and put it in his work uniform pocket before following them.

When Da Liu jogged back from the tool shed carrying the heavy dial, Jiang Ming had already placed the dial indicator on the outer edge of the chuck and it started to tick.

Three people surrounded the lathe.

Old Sun adjusted the dial, Big Liu supported the base of the graduated dial, and Jiang Ming read the micrometer scale; they worked together very smoothly.

When the first piece of oxygen-free copper billet was put on the lathe, Lao Sun personally took charge, pressing the saw blade into the copper ingot to cut off the first cylindrical billet.

The cut surface remains a clean rose-red color, without a single pore.

The sound of the saw blade biting into the copper ingot was soft, unlike the harsh sound of cutting ordinary copper; it was more like cutting a piece of hard cheese.

When Lao Sun removed the billet from the vise, the daylight outside the workshop dimmed, and water droplets began to form on the windowpanes.

The rain was light, drifting in like mist and landing on the lathe guide rails, condensing into fine water droplets.

Da Liu ran over and closed the window. When he looked back, he glanced outside again, his hand still on the window latch, not immediately letting go.

"Jiang, a jeep has arrived outside."