A strap welding tool (100) and method therefor including a first cam member (60) for moving a sealing gripper (30) toward a first support member (32) to engage and retain tensioned strap (3) disposed therebetween, a second cam member (62) for enabling a vibrator motor (48) to vibrate a welding pad (40), and a third cam member (64) for moving the welding pad (40) toward a second support member (42) to engage and weld overlapping strap portions (2,3) disposed therebetween. The tool (100) includes a relatively small base plate (110) to reduce loss of strap tension upon removal of the tool from between strap tensioned about small and irregular loads. A columnar strength of a strap portion (3) engaged by the vibrating welding pad (40) is reduced by deforming or bending the strap portion (3) over a vertex (120), and preferably forming a gap between upper and lower strap portions (2,3).