After three years of practice, Luo Ming has summed up the basic procedures for casting cannons.

One of the most time-consuming is the production of the gun mold, especially the inner mold, which needs to be made with a specific proportion of mud and then dried naturally for several months so that it can be fully dried.

If you use an inner membrane that is not completely dry, the water in it will easily heat up into steam during the casting process, and then a bubble will appear in the cast copper, which will sink down like a nest.

If there is a large bubble inside the artillery, it can be called a disaster, and when the gunpowder explodes, the force is uneven, and it is easy to explode, resulting in the destruction of the cannon and the death of people.

Although Luo Ming has always prepared more cannon molds in the spirit of precaution, there are only six cannon molds that can be used now, and four more will have to wait a month to dry, which means that this method can only cast a maximum of six cannons in this month - considering the defective rate, this is completely insufficient.

And after consulting with Aya, he came up with another solution:

Roll a cylinder with an iron plate, wrap a layer of thin mud on the outside, and heat and dry it directly over low heat at the same time inside and outside to replace the mud mold.

Of course, the drying will not be very thorough, otherwise the mud will be roasted and cracked - but in any case, it is much drier than the new mud mold, but it cannot be compared to the natural drying method.

Next, the prototype of the bronze cannon was cast with this mold, and the internal caliber of this prototype was exactly a little smaller than the actual caliber needed.

Next, a simple drilling machine is used to drill holes, and the extra part is cut off to make the diameter of the hole enlarged. A small number of bubbles generated on the surface of the bore will also be directly ground off by the drill bit, so that after reaming, what is left is a relatively fine and smooth qualified breech.

In the drilling, the copper chips are impossible to be completely recycled, there is a certain loss, and the copper is a little wasted, but Luo Ming still has a lot of copper in his hands now, which can withstand such use.

For this drilling machine, Luo Ming also specially purchased some rare metals unique to this world and mixed them with steel to make drill bits - originally used to polish the inner wall of the barrel, but now it is used here.

Although the bronze is softer, the drill bit is harder, and the drill can be drilled, but relying solely on manpower, it is still too slow.

If you rely on water power or animal power, although the strength is large enough, but you can't achieve fine control for the time being, it is easy to drill directly.

Therefore, Luo Ming came up with a method of wrapping the drill bit with fighting qi to form a thin layer of "drill bit mang" or "drill bit gas" to further increase the sharpness and reduce the resistance in the drilling work.

Using this method, you can let people manually control the drill bit, and maintain a high speed while maintaining accuracy - you can drill two guns in a day, and you may be able to complete three guns if you work overtime!

Of course, this price is not small, and the swordsman is needed to output the Dou Qi Assist - of course, the high-level swordsmen are okay, but their Dou Qi reserves are much less than those of the swordsmen, and their staying power is too poor.

Even a sword master, a simple sword master is not enough, and it must be replaced by a Pelodiana who has a greater reserve of fighting energy than an ordinary sword master.

As for the two sword masters, the phoenix-tailed chicken and even the recovery medicine are also available openly, so that the recovery speed of the fighting spirit can keep up with this work.

Maybe the swordsman who surrendered, Hudek, and the swordsman in the Jiaertai mercenary group, can also participate in this work, right?

However, you must sign a confidentiality pact with them in advance with the effect of magic.

Luo Ming briefly commended all the staff involved in the cannon casting, encouraged them to devote twelve cents of their energy to their work in wartime, announced that they would be given a raise, and then left the place, ready to move on to the next place at once.

However, before he went out, he turned back and went to the workshop in charge of casting, and conveyed a unique request to the person in charge.

"A light cannon, how much is the tail lengthened and thickened?" said the person in charge, and gestured with his hand.

Luo Ming nodded: "That's it, you have to work overnight and give priority to manufacturing it." ”

"You won't be disappointed!"

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It was already dark, and the people of Belan camped far away and began to rest, and at the head of the Iron Fire City, although most of the people had also gone to rest, there were still some soldiers patrolling dutifully.

There is a tactic in this world that allows the master to sneak attack at night. While it is true that there are some detection spells around the city that can warn you, the human eye may detect enemies earlier and warn them earlier. There are special methods that can fool the naked eye or detect one of the spells, but to fool both at the same time, the difficulty increases exponentially, and it is almost impossible.

In addition, they are also specially guarded in the air - there is a vulture horse in the Beran army, and it is not ruled out that there is a possibility that a master will parachute in on it.

Of course, if it did come, it would probably be spotted now that it was heavily guarded, and then the soldiers would shoot arrows, shoots, and even cannons into the sky.

Soldiers certainly don't have the ability to carry a cannon by hand, but small guns can be adjusted by a single person to quickly raise the angle of fire for aerial fire. At the same time, the sound of gunfire can be the most effective warning.

In addition to the soldiers, there was also a group of military dogs on the night patrol.

Ordinary dogs' hearing is much stronger than that of people, and there are several fierce dogs that meet the standards of Warcraft, and even the former Dog God Daoge Brigadier Jue, as a Warcraft whose strength is comparable to that of a swordsman, its keen senses are completely able to detect the approach of the enemy from a hundred meters away.

Soon, someone actually crashed into such a heavily guarded defense system.

A dog barked in one direction, and then Doug barked and ran towards the city, and the nearby soldiers immediately raised their guard and looked over there - several dark shadows were rapidly approaching.

They immediately took their guns and crossbows and fired in that direction, and soon another soldier adjusted a tiger squat cannon and fired a shotgun in that direction.

The shadows shouted angrily, but to no avail, and soon another cannon fired shotguns, and many soldiers nearby rushed to the city to reinforce them, so they had to retreat immediately.

The sharp-eyed soldiers could still be seen, dragging a companion who was too injured to walk.

Although the soldiers disagreed on whether the muskets, artillery, or crossbows had wounded the man, the brief clash proved the effectiveness of the city's defenses.

And the people of Belan will naturally not be happy - in this temptation, not only did they confirm that the night sneak attack was not easy to succeed, but they also injured a sword master, which was really unfavorable.