Design of stepper motors for gripper arm
 

Hello there,
I'm new to the forum and would like to ask for advice on a project that's ambitious for me. I would like to build a gripper arm which should consist of Nema 17 motors and a Nema 23 motor. The arm should be able to reliably lift 500g with a total length of 50cm at a good speed. The arm itself will be 3D printed from PETG. Now to my question. For the main axis, on which the entire gripper arm hangs, I chose this motor with 20Nm torque: https://www.oyostepper.de/goods-306-...-Getriebe.html
I need advice on whether the engine has enough power and whether the gearbox doesn't make it too slow. I have concerns about the Nema 17 motors (59Ncm), which also have a bit of mass.
I hope you could help me.