Serrar vs. aserrar vs. serruchar

In Spanish, the words 'serrar', 'aserrar', and 'serruchar' all relate to sawing or cutting with a saw, but they have subtle differences in their usage.

Serrar

'Serrar' means to saw or cut with a saw. It's the most general term used for this action, without any additional implication.
Voy a serrar este trozo de madera.
(I am going to saw this piece of wood.)
Para hacer la mesa, primero tenemos que serrar las tablas.
(To make the table, we first need to saw the boards.)

Aserrar

'Aserrar' also means to saw but is more commonly used in industrial or formal contexts. It often refers to the use of larger, more powerful saws like those in sawmills.
El carpintero utilizó una máquina para aserrar los tablones.
(The carpenter used a machine to saw the planks.)
En la fábrica, aserran los troncos para hacer tablones.
(In the factory, they saw logs to make planks.)

Serruchar

'Serruchar' is similar to 'serrar', but it typically implies using a handsaw. It can often be heard in practical or everyday contexts.
Necesito serruchar esta rama para el proyecto de jardinería.
(I need to handsaw this branch for the gardening project.)
Si quieres serruchar ese trozo de madera, asegúrate de tener una sierra adecuada.
(If you want to handsaw that piece of wood, make sure you have an appropriate saw.)

Summary

'Serrar', 'aserrar', and 'serruchar' all mean 'to saw', but their usage varies slightly. 'Serrar' is the general term, 'aserrar' is more formal and industrial, and 'serruchar' often implies using a handsaw.