Stepper motor lock function or NOT free moving

I am using a NEMA 17 2 Phase Mill Robot Lathe CNC Stepper Motor 48mm 1.5A 107oz.in. It is positioned horizontal with the load "hanging" straight down. The motor lowers and lifts the item... The rest position is UP. But the load is just heavy enough to free spin the motor and lower the item.

Is there a way to get the motor to "LOCK" in a position (up) until its triggered?

You haven't said if this is powered or unpowered.

If unpowered, power it up...

What torque is the load exerting on the motor shaft (SI units please)?.

I will post a picture tomorrow... the load is very light... maybe 16 to 24oz... its suspended by a length if fishing wire attached to a 3.75" diameter wheel.

This is what I need to implement...

Powered Holding Torque – With power applied to one winding (or several depending upon specification requirements), the motor will stay energized and hold position. Due to the increased magnetic attraction the rotor will have significantly more holding force compared to the unpowered state. This term relates to the amount of torque that would have to be applied to the rotor shaft to cause the shaft to move to the next rotor position.

The normal operation of a stepper has power applied all the time.

If the holding torque of the motor you have is sufficient then I don't understand where the problem arises ?

What stepper motor driver are you using ?
What power supply are you using for the motor (volts and amps) ?
Post your code.

If you want the motor to hold the load without power you will need some form of external lock. It may be possible to operate one with a servo.

...R
Stepper Motor Basics

stephenkamin:
I will post a picture tomorrow… the load is very light… maybe 16 to 24oz… its suspended by a length if fishing wire attached to a 3.75" diameter wheel.

I make that about 0.3Nm, which is a heavy load for a NEMA17 motor of any sort. Add
gearing or move to NEMA23.

With any mechanics question its always a case of doing back of the envelop calculations, or you
will have issues like this. And use SI units or you will make mistakes more easily.

[ My personal bugbear is the use of adjectives like “large”, “small”, “light”, “fast”, since these
are more of less meaningless unlike an actual numerical. For instance to me a large
motor is one that takes lifting gear to move. ]