How to make a puzzle with a nail

Great thing to keep guests busy. Give them a puzzle and ask, such as: "how did you put the nail there?" Naturally there will be violent controversy, which will be very interesting to watch, knowing the secret of this puzzle.
In principle, it is almost impossible to guess if you have not encountered such a thing before. Well, at the end of the discussion, you can open a secret so that guests do not burst with curiosity.

Making a trick with a nail puzzle

You will need a wooden rectangular block about 20 percent longer than the nail. This bar on the wide side should be parallel to the wood fibers, that is, when cutting, look in advance.
Then we make longitudinal cuts in it. Circular saw or manual.
Here we got to the secret. Pour water into the pan with two fingers. Turn on the fire and wait until it boils. Put the sawn bar on one side in boiling water and boil it for about 5-10 minutes.
We pull out and clamp in a vice, thereby flattening one section.
I think you have already guessed what and how will be done next.
Let the bar dry and after two days remove it from the vise. We drill a hole under the nail, because it cannot be hammered in this way - the tree will burst.
Insert the nail.
Then again we place the workpiece in boiling water with a flattened side.
After a while, the tree will soften and the section will take its original form.
Then we grind all the faces, removing possible prints and giving the workpiece the appearance of a "just sawn wood".
The result is such that no flaws are visible to the naked eye.
Therefore, this puzzle looks like some kind of anomalous miracle. Great thing to "stretch your brains" to your friends and acquaintances.