ACME thread screw and nut - torque and stresses

[Hanson Gill_1983]

Hi,

I'm calculating the stress acting on an acme screw and thread (see image attached). The screw is rotated by means of the handle to raise under a load 25000lbf. I have calculated the torque required to raise this load which is 250 ft.lbf, and found the torsional shear stress of the screw part.
Now what are the other stresses i should calculate?especially for the nut. please let me know. if you have any formula ref it would be great. thanks.

 

[EngineerTex]

Buckling?

Engineering is not the science behind building. It is the science behind not building.

 

[Jboggs]

Is there a good reason you're not using a pre-engineered screw and nut? Go with a design that has already passed by all the land mines. There are LOTS of commercial options available.