Those places that have been marked with × are the places that Xu Yi needs to remove when processing, and if they are processed vertically along the edges of those figures that have been marked with ×, various patterns will be formed on the wood.

For example, the trapezoidal shape on the side of the frame and processing will form a trapezoidal groove, which corresponds to the trapezoidal protrusion left after the sleeper end face removes other parts. This trapezoidal mortise and tenon connection looks like a swallow's scissor-shaped tail, so the concave part is called a dovetail groove on the top of the carpentry, and the bulge that matches it is called a dovetail tenon.

The application of dovetail can be traced back thousands of years, and there is a folk tale about its origin:

A long, long time ago, Luban accepted a task about building a feng shui pavilion. Lu Ban thought at the time: "Now that so many pavilions have been built, I should build a unique style!" But after meditating for three hours, he still hadn't come up with any better and more distinctive architectural methods. It was noon, and Lu Ban's wife specially made a whole fish for him, and put the fish on a plate with one end of the chopsticks into the mouth of the fish and the other end of the fish tail. When Lu Banye saw it, his eyes lit up, and he shouted loudly: "Yes, it's wonderful!" So, Lu Ban designed the pillar of the small pavilion to have two fish facing each other, and a pillar was connected by the mouth of the fish, and the fish looked at each other, and there were more than enough. The preliminary plan has been decided, but how to connect more powerfully? When he entered into contemplation, he suddenly heard the hoarse scream of Xiaoyanzi in his ears, interrupting Lu Banye's thoughts. Looking up and seeing a cute but injured little swallow hanging on two ropes for drying bladders, Lu Banye was very distressed and gently took the little swallow off. He found that the back tail of the little swallow was stuck between the two ropes in a figure-eight shape. He immediately summoned Madame to bandage Little Swallow's wounds. Place on cotton. Take care of it every day. until he recovers from his injuries and returns to nature. During this time, Lu Banye was inspired by it, and thus germinated the idea of connecting the heads of two fish with a swallowtail method to make it more vertical and resistant, and this structure was named "swallowtail structure" by him.

After all, the legend is just a legend, that is, in order to attach to the ingenuity of Luban, in fact, the dovetail is really invented by Luban?

How can it be?

Lu Ban was just a person in the late Spring and Autumn period more than two thousand years ago, something as simple as a dovetail. Where could our ancestors be so stupid as to rely on a carpenter to invent it so late?

In fact, as early as the Hemudu era more than 7,000 years ago, dovetail tenon was widely preserved in various architectural structures unearthed, or the use of this structure was invented before 7,000 years ago.

As an ancient country that attaches great importance to inheritance and traditional culture, Chinese people have always liked to pretend to be ancient sages and mythological talents.

Another typical example has to be Emperor Yan.

Emperor Yan is also the so-called Shennong, his exploits have been different since ancient times, some list four aspects, some list eight aspects, and some even list more than a dozen aspects. Almost all the inventions and creations of the Neolithic period are counted on her head.

Among the folk, the most about the exploits of Yandi Shennong are various legends in agriculture and medicine. Over time, it has become more and more numerous. Shennong's skill tree is also getting more and more perfect.

"Zhou Yi" for Emperor Yan's achievements is just a summary of his "chopping wood for the plow, kneading the wood for the plow" and "the day is the city, to the people of the world, gather the goods of the world, trade and retreat, each has its own place." When Sima Zhen of the Tang Dynasty wrote the "Three Emperors", he further summarized the exploits of the predecessors about Emperor Yan Shennong: "Chopping wood for plowing, kneading wood for plowing." It is used to teach all peoples. …… With ochre whips and whips, the first taste of herbs, the beginning of medicine. and a lyre of five strings. Teach people to be the market in the middle of the day, and to trade and retreat, each with its own place. Then the gossip is sixty-four. ”

There are also some classics that add some merits to Emperor Yan Shennong, such as "...... Shennong's ...... The land is suitable, the dry, damp and fat are high, the taste of the herbs, the sweetness and bitterness of the water spring, so that the people know what to avoid. ("Huainanzi Cultivation Training") means that Shennong is very interested in feng shui, and teaches people to choose a place to live and build houses. "Make a pottering axe. (Song "Zizhi Tongjian Waiji") and in order for him to master the skills of firing pottery and smelting axes.

The above are quite reliable, but there are also things like this: "The Book of Han" is also cloudy: the teaching of Shennong, there are ten stone cities, a hundred steps in the soup pool, and the setting of the city, starting from Emperor Yan. This shows that there were cities in the era of Emperor Yan.

"Cure its silk and linen for its cloth. (Song "Emperor Daji") that is, Shennong treats hemp as cloth and makes clothes - as a country with a long history that has already entered a high degree of social division of labor, and the male protagonist and the female protagonist are inside, you let a big man spin hemp and weave cloth, which is really scientific?

……

In fact, we have reason to believe that these inventions and discoveries cannot be completed by just one person or a generation, and they are definitely the crystallization of collective intelligence. Counting all these things on Shennong's head is just a kind of spiritual sustenance that people strive to create out of people's admiration and worship for him.

The same is true of the invention of dovetail, which undoubtedly came from long-term carpentry work, but was eventually named under the name of Lu Ban, the "originator of carpentry".

As everyone knows, such a statement has stubbornly postponed the time of the wide application of dovetail by four or five thousand years. This extremely ironic approach cannot but make people admire the blind worship of the "saint" by the Chinese people, even if there is no ancestral grave to cry, you have to find a grave to cry, and strive to lower the IQ and ability of the general public.

Similarly, for example, the saw is also attributed to Luban, saying that he invented the saw because he saw the small jagged structure on the edge of the blade of grass.

In fact, among the unearthed cultural relics, in the Stone Age more than 20,000 years ago, the use of stone to make zuò stone saws has been a common application, and the unearthed cultural relics abound, which is also an invention that has been greatly delayed by legends.

The originator of carpentry wants to worship Luban, and the theater industry has to worship Emperor Tang Ming...... Even in the Taoist classics, there are "ancestors" from all walks of life who are sold in batches, and seventy-two ancestors are forcibly made.

The phenomenon of worshipping the mountain in all walks of life has been far away for a long time, and this phenomenon is actually quite worth savoring. Or maybe this has something to do with the social atmosphere of "everything is inferior, only reading is high", and all walks of life always have to elect their own ancient sages to prove how noble their profession is, and even saints have dabbled in or even specialized - our profession is definitely not lowly!

Similar situations have existed in ancient times, and even today there is not much less.

However, it is just the time when the ministers in the palace bowed three times and bowed nine times, shouting "Long live my emperor", which became the thousands of people chanting "Long live so-and-so" a few decades ago; even now, some people still stubbornly think that when a certain person comes to power, he can really and really rely on his own strength to change some of the deep-rooted shortcomings of this ancient country......

Myths in the adult world are just as ubiquitous.

Of course, how the legend is does not affect the practical application of dovetails.

Among the many mortise and tenon structures, the dovetail structure should be said to be the strongest and most striking way to connect the ends of the planks. It connects the two plates in a staggered way with dovetail, so that the plates are firmly connected both vertically and horizontally, and has many characteristics such as high connection strength, beautiful appearance and precise structure.

Of course, Xu Yi uses the simplest single tenon structure here, and does not reach the situation of dovetail mismatch. Although the area of this sleeper is enough, Xu Yi doesn't want to be so troublesome, and he feels that it is not necessary at all. His main purpose is to rely on the tensile force between the frame and the sleeper to avoid the torsion and telescopic degeneration of the sleeper after installation, and nothing else is within his consideration.

In the case of this case, in addition to the dovetail, a square hole should be opened in the wooden frame and the sleeper above the dovetail, and then an additional male tenon is inserted into it to prevent the sleeper from sliding down.

Xu Yi is really not worried about the problem of the sleeper sliding, after all, there is still a certain friction between the sleeper and the frame, and it is not easy to loosen. And when it is officially assembled, it is necessary to add wooden wedges to those tenons to strengthen the binding force between the mortise and tenon joints, and the more afraid that the tenon will loosen. What's more, there will be a layer of wood under the sleeper at that time, and there will be no room for the sleeper to fall.

Moreover, it is not easy to install a tenon on such a thick piece of wood, and it will also cause a lot of trouble for future disassembly.

The borders of the horizon are large and heavy enough not to move lightly, and even if you don't reinforce the mortise and tenon joints that are connected to the sleepers, it is difficult to make them move. And when something really happens to the horizon, you can also remove the bamboo nails on the mortise and tenon on the frame, disassemble the frame again, and repair the horizon.

Xu Yi moved all these components to the corresponding machine and processed them with the machine. These machines are really good, and most of the things that Xu Yi wants to process can be processed with these machines, but there are always some structures that are not suitable for these machines, and Xu Yi has to rely on manual manufacturing of them. These machines are also inseparable, they are also only personal devices, and the processing efficiency is always limited. Moreover, most of Xu Yi's lines are drawn with pencils, which also brings a lot of trouble to the processing. Often, Xu Yi has to repeatedly trim the processed things to make their accuracy meet the standard. There are many components themselves, and they have to be modified repeatedly, so Xu Yi spent a total of twenty or thirty hours before and after processing them.

Stacking all the components in one place, Xu Yi began the formal assembly work. (To be continued......)