Fig.: to have a personal gain in something

In writing the unauthorized biography about the president, the author failed to account for sources who might have their own ax to grind

Nello scrivere la biografia non autorizzata del presidente, l'autore decise di non tener conto di fonti che potessero avere un interesse troppo personale

When Carol says that fresh flowers are the best present for a woman, she's just furthering her own cause because she owns a flower-shop

Quando Carolina afferma che il miglior regalo per una donna è un mazzo di fiori freschi, non fa altro che gli interessi della sua parrocchia visto che ha un negozio di fiori

The tobacco corporations say that smoking is not that dangerous after all: bullshit! They have their own agenda!

Le grandi compagnie del tabacco dicono che il fumo non fa poi così male: balle! Tirano solo acqua al loro mulino!

Such expression comes from a story entitled "Who'll turn the grindstone?" first published in the Wilkesbarre (Pa) Gleaner in 1811, often credited to Benjamin Franklin, but actually written by Charles Miner. He described how, as a boy, he encountered an agreeable stranger carrying an ax, who inquired if he could borrow the family grindstone. Young Miner naturally said yes. The man then asked him in amiable tones if he was strong enough to turn the grindstone; Miner proudly said that he was, and offered to demonstrate. The smiling stranger, holding the ax to the stone, praised the boy's industry, but when the ax was ground, walked off without a word of thanks. Thus, said Miner, "When I see a merchant over-polite to his customers, begging them to taste a little brandy... thinks I, that man has an ax to grind" (Claiborne, 19)