Explain Joe's play on the two meanings of the word "hammering"

In Chapter VII, Joe is impressed with Pip’s having learned his letters and how to write. For, he has been kept from an education because his father was a drinker who became violent, beating both his mother and him. As Pip relates, this punishment Joe terms “hammering”; his father hammered upon Joe’s mother without mercy, and when he tired of that, he began hammering upon Joe. Hammering, thus, means striking repeatedly with the fist .

Further, Joe tells Pip that whenever he would attend classes at someone’s home, his father would knock at the door and create such a distraction that the teacher would feel threatened into releasing the boy. This, Joe explains to Pip, is the only hammering his father has done. For, he did not literally pound his hammer on his anvil (he must have been a blacksmith,too) or do anything constructive with the hammer.

In Chapter VII, Joe is impressed with Pip’s having learned his letters and how to write. For, he has been kept from an education because his father was a drinker who became violent, beating both his mother and him. As Pip relates, this punishment Joe terms “hammering”; his father hammered upon Joe’s mother without mercy, and when he tired of that, he began hammering upon Joe. Hammering, thus, means striking repeatedly with the fist .

Further, Joe tells Pip that whenever he would attend classes at someone’s home, his father would knock at the door and create such a distraction that the teacher would feel threatened into releasing the boy. This, Joe explains to Pip, is the only hammering his father has done. For, he did not literally pound his hammer on his anvil (he must have been a blacksmith,too) or do anything constructive with the hammer.