Chen Xian has never forgotten that he is a traverser, and his biggest advantage is not only his thoughts, but also his skills.

Therefore, Chen Xian began to think about restoring the arquebus from a very early stage.

The biggest difficulty in restoring the arquebus is the manufacture of the barrel.

In this era, the manufacture of gun barrels could only be done by hand hot forging.

A piece of iron, forging a rectangular plate, and then this plate is burned red, using the semi-circular groove on the anvil, and the V-shaped iron hammer, the red-hot iron plate is hotly rolled into a tube type, and a round iron rod is placed inside the tube type when forging, so as to prevent the inner hole of the round tube from closing during the forging process.

After forging until the round pipe wall is closed and overlapped, the iron pipe is calcined again until it is red-hot, and the pipe wall can be welded by quickly hitting the red-hot pipe wall overlap with a small iron hammer.

Through this kind of curling hot forging many times, an iron plate can be forged into an iron pipe. Finally, use a small hammer to shape and trim until the round pipe is roughly regular.

The inner wall of the forged iron tube is very rough, which cannot be used directly to fire bullets, and it is also necessary to reaming the inner wall of the barrel to make the internal size uniform and smooth.

To reaming an iron pipe of about one meter is definitely a high-end technology in this era, and what Chen Xian can think of at present is to use a hand crank drill and water grinding kung fu to drill and ream.

After the iron pipe is reamed, it is externally reground and measured with a special clamp gauge to ensure that the thickness of the barrel wall is uniform, and it can be installed on the buttstock, but at this time, there is another seemingly small problem.

At this time, the barrel is passable, and cannot be used to fire gunpowder bullets, so the rear end of the barrel must be sealed, how can the rear end of the barrel be sealed safely and reliably?

The answer is bolts, yes, the question goes around the bolts again, Chen Xian wants to make an arquebus, he first has to make bolts!

Well, this time Chen Xian can't get around it anymore, for armor, he can settle for the second best thing and choose cloth armor, but he must not give up the musket, this time, he must overcome the problem of bolts......

In the past six months, Chen Xian has been thinking about how to use the technological level of this era to make a screw making machine.

After half a year of thinking, he finally had an eyebrow in his heart.

With the level of craftsmanship of the Song Dynasty, it is of course impossible to make a lathe in the modern sense, but it is not impossible to make a simple machine similar to the principle of a lathe.

Chen Xian remembers that when he was visiting a forum before, he once saw a post in which there was a sketch of a threading device drawn by Leonardo da Vinci, and it is said that the original version of this sketch is in the famous "Da Vinci Manuscript".

It is well known that Leonardo da Vinci, in addition to being a great painter, was also an imaginative genius of mechanical design, and there were many whimsical designs in his manuscripts, compared to which this threading device seemed prosaic.

The reason why Chen Xian remembered this post was entirely because this low-looking sketch was drawn by Leonardo da Vinci.

As an engineer, the machine on this sketch is simple for Chen Xian, and he doesn't need to take a second look.

In the sketch, there is a square frame, on which two cylinders are fixed, one cylinder is the part to be machined, and the other cylinder is a lead screw, the lead screw is equipped with a slider, the slider has a thread matched with the lead screw, and a cutter sticks out from the slide block, aiming at the work to be processed side by side with the lead screw.

At one end of the lead screw, a crank is connected, the other end is connected with a gear, and at the same end of the machined part, a gear is also connected, and the two gears are engaged with each other.

When the crank at one end of the lead screw is rotated, the crank drives the lead screw to rotate, and the screw rotation will drive the slider to move forward through the thread, and at the same time, the screw rotation will also drive the gear at the other end to rotate, and the gear will drive the gear connected to the workpiece next to it to rotate.

In this way, a linkage relationship is formed between the slider and the workpiece, and the result of this linkage relationship is that the tool on the slider cuts a thread similar to the thread on the lead screw on the rotating workpiece.

This linkage is not unlike a modern lathe, and you can think of this primitive wooden box as a simple lathe, and although their complexity may seem like the difference between a primitive assault gun and a machine gun, they are really the same thing.

With the craftsmanship of the Song Dynasty, of course, it was impossible to build a modern lathe, but it was not impossible to build a simple machine designed by a genius of mechanical design in the fifteenth century.

Combined with what he had in his hands, Chen Xian slightly modified the design of Leonardo da Vinci, and he canceled the double-rod linkage design and adopted a single-rod design.

Specifically, it looks like this.

He designed a wooden frame with a nut brought back from the car in the center of one of the end faces of the frame.

Next, Chen Xian attached a crank to the end of a long bolt, and then screwed the long bolt into a nut mounted on a wooden frame.

The end of the bolt through the nut is fitted with a connecting pipe with an internal thread at one end and a bolted connection at the other end and a hexagonal hole at the other end.

The internal thread of the connecting pipe is used to install the bolt head, and the hexagonal hole at the other end is used to install the bolt blank to be machined, and the tail end of the bolt blank is forged into a hexagonal shape.

The tail end of the bolt embryo to be processed is loaded into the hexagonal inner tube of the connecting tube and clamped with a wedge.

After clamping, shake the crank, rotate the bolt, the bolt will advance against the blank, until it reaches the board on the opposite side of the frame, there is a round hole lined with iron sleeve at the same position of the board on the opposite side of the frame, and the bolt blank will be pushed into this round hole by the bolt.

On the outside of the board at the other end of the frame, a cutting tool is installed, the tip of the tool is just facing the edge of the round hole, and when the bolt is rotated to eject the round hole, it will be cut by the tool.

As the rear thread rotates, the front bolt blank will follow the spiral forward action, and the tool will copy the thread of the rear bolt on the front bolt embryo.

When the threading is long enough, the bolt embryo can be reversed by reversing the bolt, and then the tool is moved forward slightly, and the bolt is rotated again to repeat the previous processing......

After several times, a new bolt with a sufficient thread depth is machined.

This threading device is simpler and more compact than the Da Vinci design, and more importantly, it is also easier to achieve when Chen Xian has ready-made high-quality bolts.

The only challenge in the design of this screw-making machine was the forging of the connecting tubes.

After all, the connecting pipe needs to have a hexagonal bore at one end, and a round bore at the other end, and the bore must also be threaded.

But that didn't bother Chen.

The first is the blank of the forged link tube, which can easily be curled into an iron pipe with a semicircular groove on the anvil and a special V-shaped hammer, just like a forged gun barrel.

When processing one end of the hexagon, you can use a hexagonal steel rod as a lining, and the forged inner tube will naturally be hexagonal, and the round hole can be lined with a round bar at one end, and you can get a circular inner hole.

In order to obtain an accurate threaded bottom hole, Chen Xian used a hand crank drill to reamed a section of the round pipe of the connector.

Later, Chen Xian transformed a bolt brought back from the car's toolbox into a tap.

He carefully sharpened the stripping groove on the bolt with a file, carburized and heat treated the surface of the bolt, and processed the bolt into a simple tap, which was used to tap the thread on the connector......

With this screw making machine, Chen Xian can not only directly manufacture screws, but more importantly, he can use this screw making machine to make taps, make plate teeth with taps, and then use taps and plate teeth to manufacture bolts and nuts in large quantities.

The advantage of the screw making machine is that you can move the tool to ensure the thread depth of the screw.

With this screw making machine, Chen Xian is equivalent to having a mother machine, and he can copy a new screw making machine at any time.

After the successful trial production of the screw making machine, Chen Xian immediately began to trial produce arquebuses.