Everyone was shocked when they heard this, especially Xu Erlu, an expert who thought it was true-the pores have always been the culprit of the explosion, and without the pores, the yield will inevitably increase exponentially. And without grinding the chamber, this step alone can save at least ten days!

In fact, there are many advantages of the iron fan casting cannon that Su Chengyu did not say, such as the iron inner fan is stable and not easy to skew when pouring. There is also a fast speed of iron fan de-normalization, after the de-normalization, the gun body is still red-hot, such as trimming the unevenness of the gun body, drilling the fire door and other processes can be carried out at this time, which is several times easier than the gun body after cooling.

At the end, Su Chengyu simply added, "Of course, I will solve the problems in the details of the process." ”

Then he began to explain in detail to Xu Erlu and the craftsmen the process of casting the cannon of Tiefan.

Iron fan is also an iron product, so naturally it must be cast with clay fan first. Therefore, first of all, it is necessary to make a clay fan, which is the opposite of the clay fan of the cannon, which is equivalent to using the mud to make the shape of a cannon.

However, compared with the cast cannon, the clay fan of the cast iron fan does not have to worry too much about the pora, after all, it will not bear too much pressure, so its clay fan is much easier to make.

For the sake of convenience, the iron fan is not cast into the size of the entire cannon, but is divided into several sections. The two-thousand-pound cannon can be divided into four sections. Each segment is divided into two lobes, left and right.

When casting the cannon, the two petals of each section are buckled together, and then all the segments are stacked together, and the outer layer can be tightened with an iron hoop up and down, left and right.

Immediately, a craftsman asked, "What if the copper water and the iron fan are burned together?" ”

The craftsman who used iron fan to make agricultural tools in his hometown smiled: "Those who have cast hoes and iron forks know that the inner wall of iron fan is to be brushed with compartments. The blacksmiths in the village mostly use fine ash, mud and sand to paint the inner walls, and then brush them with coal ash and water. ”

Su Chengyu nodded, "That's right." "In fact, the cladding of the inner wall of this iron fan is the same as the raw material used for sand mold casting. The molding sand used for casting in later generations is generally a mixture of extremely fine sand, fine clay, tung oil, and carbon powder. However, it is not necessary to cast such a large part of the jack cannon as fine, and it is enough to use the soil method.

After confirming that the craftsmen had figured out the details of the process, Su Chengyu instructed everyone to start making clay models for cast iron models.

In order to ensure the uniformity of the whole clay model, the current model making process is to continuously rotate the clay model on a huge wooden pole, and use centrifugal force to make it uniform in all directions.

The cylindrical clay fan is naturally more convenient to rotate with a wooden pole, unlike the clay fan used for casting cannons, which also needs to be supported by a lot of wooden parts.

These craftsmen are skilled and can make the clay in just one afternoon. In order to speed up the drying process of the clay fan, Su Chengyu also asked the craftsman to add some gypsum to the raw materials on the outer layer of the clay fan. And to be on the safe side, he also asked the craftsmen to make a few more clay models for backup.

After the craftsmen have placed the clay fan in the shed, all that remains is to wait patiently for it to dry.

After a day of contact, Su Chengyu learned that this Xu Erlu was a famous person, and it had only been two months since he came to manage the Ganzhou Ordnance Bureau.

It was Yang Tinglin who relied on his personal friends to ask him to come to Ganzhou from Shanghai to help in order to cast cannons.

Xu Erlu originally thought that he had a lot of experience in casting cannons, but after meeting Su Chengyu this time, he knew that there were people outside the world.

In addition to this iron fan cast cannon, he was dumbfounded when he heard the concepts of rifled guns, breech gun latches, optical sights, etc., mentioned by King Chen Zhou during the conversation. Although it sounds extremely unbelievable, letting Su Chengyu say it like this makes him feel very reasonable, and it is even expected to be realized soon.

That night, Xu Erlu personally sent supper to the post house where King Chenzhou stayed, and then took the opportunity to ask for some "high-precision" cannon casting knowledge.

Su Chengyu does not hide his selfishness, he must answer any questions, in the end, he can cultivate one more technical talent for Daming.

Later, the two talked about firearms from cannon casting, from firearms to natural science, and finally Su Chengyu simply thought of all kinds of mathematical, physical and chemical knowledge and said anything.

This Xu Erlu is also quite good, he has a very solid foundation of modern scientific knowledge, and he can understand fifty percent of what Su Chengyu said.

The more he listened, the more surprised he became, all kinds of unheard of concepts, theorems, and formulas Su Chengyu came to him, and the angle of thinking about the problem was extremely novel, and it took him a moment to have a sudden enlightenment.

Seeing that it was late at night, he didn't dare to delay Su Chengyu's rest, so he got up and said goodbye, and before leaving, he sighed with emotion: "Xiaguan's grandfather has studied geometry and arithmetic for many years, and Xiaguan thinks that he is the leader of the Ming Dynasty in this regard. When I met His Highness today, I realized that His Majesty's knowledge was really limited. ”

"Study geometry and arithmetic?" Su Chengyu's heart jumped, and he still thought he was a leader? He hurriedly asked, "Dare to ask Ling Zuzun's name?" ”

Xu Erlu solemnly arched his hand and said, "Go back to Your Highness." Xiaguan's grandfather was the second assistant of the cabinet of the Chongzhen Dynasty, and he was secretive of the light and the bottom. ”

"Enlightenment?" Su Chengyu was stunned for a moment, Xu Guangqi?!

No wonder he dares to say that he is a geometry leader, this is the first scholar in China to translate the "Geometric Original", the "academician of the Chinese Academy of Sciences" of the Ming Dynasty!

He suddenly remembered that Xu Guangqi had five grandsons with the word "Er" in their names, all of whom had some knowledge, and eventually gave birth to a huge family. Xujiahui in Shanghai today is named after the people who used to live here.

Then this Xu Erlu should be one of them.

It is no wonder that he has a solid foundation in geometry and mathematics, and has a lot of research on cannon casting, which turns out to be a family history. You must know that in history, since Xu Guangqi's death, it has been difficult for the Ming Dynasty to cast high-quality Hongyi cannons.

Yang Tinglin was able to invite Xu Erlu to manage the Ordnance Bureau, and he really got a good general.

Su Chengyu hurriedly saluted: "Look up for a long time." Ling Zushi is the first person to enlighten the wisdom of Ming geometry! Many of the things I learned below were derived from the Geometric Primitives. ”

"How dare you." Xu Erlu hurriedly said, "If his old man is still alive, I'm afraid he will have to ask His Highness for advice." ”

So in the next few days, Xu Erlu came to pester Su Chengyu to ask for all kinds of knowledge whenever he was free.

Su Chengyu simply followed Xu Erlu's foundation and began to teach him high school mathematics and junior high school physics and chemistry courses, so that he could learn more systematically.

Three days later, Su Chengyu had the mud fan moved to a ventilated place and placed a charcoal fire five feet away to smoke it. Usually it takes more than a month to dry in the shade, but he doesn't have that much free time.

He was not reckless in doing this, firstly, the clay fan of the iron-making fan was divided into four sections, which was much smaller than the clay fan of the cannon-making, and it was also done quickly. Second, it doesn't matter if there are tiny cracks in this mud fan, you can smooth it with mud and water before burning it dry, the iron fan is not as squeamish as a cannon, it can be repaired and polished.

Before the cannon could be cast, Su Chengyu asked Qiao Qian to return to Longnan and bring the gunner named Anthony who had been recruited from Macao to Ganzhou. He has been working as an artillery theory instructor recently, and now is the right time for him to come to the Ordnance Bureau to show his expertise.