BFA (Backtrack Free path planning Algorithm) has been implemented for calculating paths of manipulators behaving in 3-dimensional work spaces. In the implementation, a method to avoid collisions between links also has been proposed. This paper also discusses an approach to extending BFA for path plannings of cooperating multi manipulators. In the approach, multiple manipulators are considered as a single composite one with many links. Simulation results demonstrated that BFA enabled the efficient generation of paths both for single and multi manipulators. The algorithm is backtrack free and resolution complete. Computation volume of the algorithm is proportional to the total number of links and does not change with environments where manipulators behave.