This research attempts to improve the spatial interaction in virtual assembly with a focus on bimanual object manipulation. Using a unique combination of spatial interaction devices namely a kinesthetic haptic device (Phantom Omni®) and a magnetically tracked device (Razor Hydra) each held in one of the user hands; a new interaction technique named ‘Bimanual Stretched-String Single Object Manipulation’ (BS-SSOM) was developed [1]. The BS-SSOM technique decouples positioning and orientation of objects during bimanual single object manipulation in virtual assembly. The distance between the two hands can be varied to control the precision of manipulation. The simulation uses Voxmap Pointshell [2] physically based modeling library. The (BS-SSOM) technique is evaluated with a user study. Three modes of manipulation and 3 task levels are designed to give 9 treatments for evaluation. A method to measure the task completion along with task time and distance covered by each hand in virtual assembly is devised. In order to facilitate long tasks a progressive assembly scheme is implemented. Participants were screened for normal visual acuity, stereopsis and manual dexterity. Results of the user study provide good indicators for evaluation of hypotheses regarding participant performance, realism of interaction, hand motion and effect of task length on utility of the interaction method.