With a faint feeling of concern, Rihito returned to Merlin and the craftsmen, who had already begun to work on the molds. At Merlin's request, the blacksmiths began by casting gears with high precision. A blacksmith found the carpenter with the drawings drawn by Merlin and asked Mujiangmen to build a mold out of wood as required. Rihito, who was on the side, saw it and immediately knew that the blacksmiths were going to use the sand turning method to cast gears, but Rihito only knew the theory and didn't know how to operate it in practice, so he watched carefully on the side with curiosity.

After the carpenter handed the finished pinion to the blacksmith, the blacksmiths began to pile up the wooden frame with a very oily sand, and when the sand of the wooden frame was full, the blacksmiths immediately smoothed it out. At this time, they soaked the finished wood mold in water, put it in the sand, and pressed down vigorously until more than half of the mold entered the oil sand. A carpenter placed a large wooden frame on top, exactly the same size as the one below. When they had filled up the oil sand, they added a thick wooden pier on top of it, and the wooden pier fit into the top box. So the blacksmiths took the sledgehammers and began to beat them on the wooden piers.

Boom! Boom! Boom! The sound of tapping on the wooden pier reached Liren's ears, and Liren only then turned out Baidu's introduction to sand turning in his memory in his previous life:

Sand turning is also known as "casting"

Sand turning is a production method in which molten metal is poured into the cavity of the mold, cooled and solidified, and the product is obtained.

The raw material of the sand mold is mainly sand, which is mixed with binders, water, etc.

The sand mold material must have a certain bond strength in order to be molded into the desired shape and to resist the erosion of hot molten iron without collapsing. In order to mold a cavity inside the sand mold that matches the shape of the casting, a model must first be made out of wood, called a wooden mold.

The volume of the red-hot molten iron will shrink after cooling, so the size of the wooden mold needs to be increased according to the shrinkage rate on the basis of the original size of the casting, and the surface that needs to be cut is thickened accordingly. The hollow casting needs to be made into a sand core and the corresponding core wood mold (core box). With a wooden mold, it is possible to turn over a cavity sand mold. When making a sand mold, it is necessary to consider how to separate the upper and lower sand boxes to take out the wooden mold, as well as where the molten iron flows from and how to fill the cavity to obtain a high-quality casting. Once the sand mold is made, it can be poured, that is, molten iron is poured into the cavity of the sand mold.

Now the blacksmiths should make the sand mold stronger, because there is no good binder for strengthening the sand.

Thinking of this, Liren asked a little strangely: "Masters, you have already put the mold inside, but how do you take the mold out?" ”

Hearing Rihito's question, one of the blacksmiths said, "We'll slowly separate the two connections in the middle, and then close them slowly." ”

"Oh!" Now Rihito understood, but he thought carefully and said, "If the accuracy I require is very high, what should you do?" ”

"In that case, we will make the mold a little bigger, and then take it out and modify it slowly after molding." The blacksmith said.

Rihito nodded and said, "What modifications do you usually use?" ”

The blacksmith thought for a moment and said, "We usually use iron files for modification. ”

"Oh! Can an iron file file steel? Liren asked thoughtfully.

The blacksmith was immediately stopped by Rihito's question, and he couldn't say clearly. At this time, Rihito said: "Now you can use an iron file to file the steel that has been cast, and you will know if you try it." ”

When the blacksmith heard this, he immediately smiled and nodded, and took his iron file to the side of the steel block to test. The blacksmith filed for a long time, and not even a single skin was rubbed off the steel block, and the file was filed.

The blacksmith was dumbfounded, and at this time, Merlin next to him also came over to look at it and asked curiously, "What is the lord doing at this time?" ”

"Huh! Didn't do anything, you can see for yourself! Rihito said, pointing to the file in the blacksmith's hand.

Merlin was dumbfounded when he ran over when he heard this, but he smiled and said, "Isn't it just a file?" ”

"It's just a file, but it can't be filed, and that's a big problem." Rihito said.

"What's the big problem?" Merlin asked inexplicably.

Pointing to the gear drawing in his hand, Rihito said, "This is a big problem, you know that the gears need to be very tight with each other, and if there is a problem with one of the teeth in the gear, the back gear will be stuck instantly." But there are two general reasons why gears go wrong. First, there is a foreign object stuck in the middle of the gear. Second, there is a problem with the gear itself, especially the reason for the second point is the inaccuracy of casting. At this point, Rihito paused and looked at Merlin.

Merlin reacted instantly, and the blacksmiths didn't think about the seriousness of this problem at first, and only paid attention to what Li Ren said. Merlin asked, "What then?" ”

"The solution is not only to pay attention to the accuracy of the casting parts when casting, but also to pay attention to the fine grinding and modification after casting. So now a small file is the key to restraining you. After Rihito explained the problem clearly, he got to the point: "That's why you have to make a file right away." ”

As soon as he said it, he asked the blacksmith to take out a little bit of the steel and make a sharp steel slaughter, and then quench the steel slaughter. Then use a section of steel to make it look like a steel file, and then burn red and anneal. Then use steel to slaughter a little bit on the surface of the annealed steel file embryo, and deeply slaughter the fine file text. When everything is ready, Liren personally picks up the steel file embryo and burns it red, and when the steel file embryo is red, he asks the blacksmiths to pour pig iron water on the red-hot steel file embryo, everything is done, and then let the experienced blacksmiths quench to improve the hardness of the steel file.

In this way, a file was produced, and the blacksmith took the black file and tried it on the steel block, and all the blacksmiths laughed happily. At this time, Merlin, who often saw blacksmiths quenching, asked Liren: "My lord, why did you pour pig iron water on the surface of the steel file just now?" ”

Li Ren smiled and said: "The main purpose of using molten pig iron is to improve the hardness of the surface of the steel file, you can try to use the original wrought iron to burn red and pour the molten pig iron, and then quench." The iron knife that comes out in this way will be harder than the original iron knife. ”

The blacksmiths experimented one after another, and sure enough, the hardness of the Pu knife made of iron was greatly improved after pouring pig iron with molten iron, and there was a blacksmith who had the best quenching mastery of the Pu knife he made actually cut the pure iron knife at once.

At this time, Liren's eyes lit up, and he said to the blacksmiths with a smile: "You first experiment with casting gears, and then make artillery when everything is mature, Merlin, you will be responsible for supervising it in the future, oh!" And come to me in the evening. ”

After saying that, Liren turned around and walked out with a iron knife and a knife drenched in molten iron, and Merlin and the blacksmiths were quiet in their own little world.

After returning to the small courtyard, Li Ren immediately instructed the guards: "Go! Call Mr. Fang to me. ”

After a while, Fang Ning walked in from outside, and after seeing Li Ren, he asked, "I don't know what the lord is looking for me?" ”

Rihito walked up to him from behind the table with two knives that he had just brought out of the steel mill, handed them to him and said, "Try it yourself, see how the two knives are different." ”

Fang Ning and his gang took the two black and unpolished knives, looked left and right to see how they couldn't find any difference, then he asked Liren: "Please solve your doubts!" ”

Rihito smiled and said, "You use one knife to cut another knife and try to see the difference." ”

Fang Ning did what he did, and after taking a closer look, a deep gap was actually cut on a knife, and he was suddenly startled and said, "Could it be that this is the treasure knife that the lord just created?" ”

"Haha! What kind of treasure sword, you have a knife made of iron in your hand, and there is no treasure sword. Rihito said with a laugh.

Fang Ning was even more puzzled, and after putting the knife in his hand that cut out the gap on the table, he pointed to the knife in his hand and asked, "It's not a treasure knife, why is this knife so sharp?" ”

"It's not worth anything if you say it, haha, you don't care how it came out now, just tell me, if I can make thousands of this kind of knife, how much can you sell it for me?" Rihito asked with a smile after taking a sip of tea.

Fang Ning was stunned for a moment, and immediately asked, "Can the lord really make thousands, ten thousands?" ”

Rihito nodded and said, "Yes, I can make it, and I can make it even better than this!" ”

"Such a treasure knife is close to a hundred steel knives, it is hard to find, if the lord can make a good one, it is ten thousand gold." Fang Ning said affirmatively.

Li Ren laughed and said, "Okay, you are responsible for contacting the buyer, and I will make the treasure knife." How soon can you turn me into silver? ”

"Don't worry, my lord, this kind of treasure knife, my lord will give me a hundred first, but I want ten better ones. Give me another month, and I will definitely send back 100,000 gold to my lord. Fang Ning said with a little swear.

Rihito squinted his eyes and thought for a while and said, "Yes, you can draw a pattern first for whatever style you want, and after seven days, you will be guaranteed to get something." ”

Fang Ning immediately said: "Don't use anything else, just use a hundred Pu knife styles and ten sword samples." After seven days, the lord must hand it over to me. ”

Rihito said, "Good! When the matter is completed, I will give Mr. Fang the wind. ”

In the evening, Merlin came to Liren's room, and Liren took out the previously printed "Basic Course of Physics" and handed it to him, and took out the "Metallurgical Basics" he had written, but Liren played a trick and changed the book to "The Secret of Alchemy". Merlin took the book in his hand, and immediately asked Liren suspiciously: "May I ask my lord, is there really an alchemy in the world?" ”

"Huh! Time has the art of alchemy, but this alchemy is not the alchemy of the other. Rihito said with a smile.

Merlin asked, "What's the explanation?" ”

"Alchemy, as the name suggests, refines gold, what in the world can refine gold out of thin air?" Rihito asked, standing up with his hands behind his back.