One embodiment of the invention provides a chalk line device having a helical gear and an improved locking assembly. The locking assembly comprises a first lock member having a lock button. The locking assembly also comprises a second lock member including an opening to lockingly engage the first lock member and having a plurality of teeth at one end disposed adjacent one of the helical gears used in this embodiment. The second lock member engages with the helical gear in response to a movement of the lock button member.