Stepper motor specifications

Hello,
I was looking for a stepper motor for a project of mine and found this one:
pololu.com/product/2690
Now in the data sheet it has the two entries
Max.radial force (N)
Max.axial force (N)
what do those specify exactly? The motor (with the lead screw facing upwards) is going to drive a mass up and down. Now calculating with the given torque values, it should be definitely sufficiently sized (the mass is going to be 2-3kg and according to calculations the torque should be able to drive a mass of something well above 10kg) - but the “Max.axial force (N)” is given as 10. Does that mean I can not drive a mass of more than about 1kg (making the force just under 10N) up and down (which would be axially with the motor facing upwards)?

[quote]Does that mean I can not drive a mass of more than about 1kg (making the force just under 10N)[/quote]That is my reading. The motor probably does not have a thrust bearing, which is required to support axial loads. Even if you limit the mass to 1 kg, vertical movements will wear out the bearings rapidly.

The maximum radial force would be the maximum sideways load on the lead screw at a distance 20 mm from the flange. It would decrease proportionally as you move further out from the flange.

If you need to lift significant masses, a linear actuator with an encoder would be a better choice.