What was the last trick that the blacksmith taught his disciples in the old days?

The last trick that the master blacksmith taught his disciples in his later years may be varied, depending on his teaching methods and personal experience.

Some possible processes include:

1. heat treatment process: this is one of the most important skills in blacksmith's work. By heating and cooling, the hardness and toughness of the metal are changed, so as to achieve the purpose of making the required parts.

2. Ironing skills: This includes using bellows, hammers, anvils, pliers and other tools to beat metal blocks into required shapes and sizes.

3. Grinding and polishing: This is an indispensable part of the blacksmith's work. By grinding and polishing, the metal surface becomes smooth to achieve the required smoothness and accuracy.

4. Welding technology: This includes using soldering iron, soldering tin and other tools to connect metal sheets or wires together.

5. Quenching and tempering: This is a common process in blacksmith's work. By heating and cooling the metal, the hardness and toughness of the metal are changed to achieve the required mechanical properties.

In a word, the last trick taught by the blacksmith master in his later years is often a highly refined and summarized work experience and skills, which is an important legacy worthy of inheritance and development.