The smith machine shoulder press is a viable option for moving heavy weight without a spotter.
Dont lock your elbows out at the top of the movement.
Always warm up first to lower your risk of shoulder injury.
Always lower the bar below your chin to complete a long range of motion.
Instructions
Set up for the smith machine shoulder press by setting a bench down in the smith machine and adjusting the back to a 90 degree angle.
Now sit down on the bench and adjust the position so that the bar comfortably comes down just in front of your face.
Next, add the weight you want to use and sit down on the bench.
Un-rack the weights and bend your elbows slightly. This is the starting position for the movement.
Slowly lower the weight down until the bar is just below chin height, pause, and then raise the bar back to the starting position without locking your elbows out at the top of the movement.