An improved safety IV placement device includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after placement of the IV cannula and removal of the needle from within the cannula. An internal spring, which engages the sheath, expands to move the sheath to cover the needle point prior to placement of the IV cannula and after the needle is removed from the indwelling cannula. The spring is a non-uniform helical spring having multiple 360 turns each turn uniformly spaced from adjacent turns.