How to stop a stepper motor when certain force applied.

Hi Experts
I am working on a project and need expert help I want to stop a miniature horizontal ball screw stepper motor when it senses 0.5 to 5 pounds force or torque (adjustable) .
What type of sensor I need . Screw length is 36 Inches.
Please suggest how can I run and control it ?
Thanks

You probably need to couple the actuating shaft to a strain gauge...or maybe a pressure sensor...

Yes, I have a head nut on the screw ,when that nut puts a set force on the other side a *stationary post *of the screw and makes micro stepper motor to shut down.

You might be able to use stall current (in the stepper motor windings) to detect the force.

Thanks Steve
Can you please explain how. I am a learner and not familiar with stepper motors working.
Thanks and obliged.

Use a small series resistance inline with the motor coil(s) and see if there is a consistent, detectable correlation between the voltage across the resistance (i.e. the current) and the torque on the shaft. If there is a common line, try the resister there.

I would need to know more about your setup to go any further -- and even then, you'll have to experiment to determine if this is even viable (I've never tried this myself).

Also, I'm a dunce when it comes to things mechanical -- I have no idea what a "head nut" is or a "stationary post" or a "set force". But, I probably don't need to know