En casa de herrero, cuchillo de palo

Significado: La persona que se especializa en algo no necesariamente lo aplica en su vida. A veces falta una cosa en el lugar donde nunca debiera hacer falta.

Ejemplo: Fuimos a entrevistar a un escritor, pero él no tenia ninguna copia de su libro, bueno en casa de herrero cuchillo de palo.

VOCABULARY

la casa: the house
el herrero: the blacksmith
el cuchillo: the knife
el palo: the stick

En casa de herrero, cuchillo de palo

Literally it says: In the blacksmith’s house, wooden knife.

When someone specializes in a certain type of trade/labour (usually making or fixing something) that sometimes they neglect themselves or their family in that same area.

Like saying if a blacksmith is good at making things out of metal, then why does he have wooden knives (which are not as good as metal/steel) knives in his house.

It’s like a Marriage guidance counselor that is divorced.
A mechanic’s car that keeps breaking down.
A doctor that smokes heavily and is always sick.
A translator’s website only in one language

Another Variation

Sometimes the expression is: En casa de herrero, cuchara de palo
Cuchara = spoon