An exemplary molding assembly includes: a first mold housing defining a first engaging hole; a second mold housing configured for attachment to the first mold housing; a containing block received in the first mold housing and defining a second engaging hole; a first core member received in the first containing block and having a molding surface thereon; a second core member received in the second mold housing for matching with the first core member; a first elongated adjusting member having a first portion locked by rotational engagement in the first engaging hole and a second portion in threaded engagement with the containing block; a second elongated adjusting member having a first portion locked by rotational engagement in the second engaging hole and a second portion in threaded engagement with the first core member. Lengthwise directions of the first and the second elongated adjusting members are oriented perpendicular to each other.