A customer once sent me a message:

“I need a 1610 ball screw for my CNC router. 1000mm travel. Quote please.”

I asked what motor he was using. He said a NEMA 23 stepper, around 3 Nm, with a 36V supply. Then I asked how fast he wanted the machine to move.

He said, “As fast as possible.”

That’s when I knew the 10mm lead was probably a mistake for his setup. Not because 10mm is bad, but because his motor wouldn’t have enough torque to actually use the speed he was imagining. He had picked the larger lead because it looked faster on paper.

That conversation happens a lot. People see “10mm lead = double the speed” and stop the calculation there. But lead changes more than speed. It changes thrust, acceleration, motor RPM, and sometimes the whole feel of the machine.

So if you’re trying to choose between 5mm and 10mm, let me walk through how I actually think about it.