Caluate Shear Stress?

I would not use three bolts to hang a rectangular frame. There should be one bolt on each corner.

You did not give the shape of the enclosure. That detail would be helpful.

Three 1/2" bolts to hold 70 pounds?

YES - they have adequate strength

(depending on if they pull out from what they are attached to though)

Is the enclosure 70lbs when it is full or empty?

If empty, what is the volume and what will it contain?

A 1/2 Inch SS bolt has approximate shear of approx 1920 pounds per square inch as long as the stress is not on the threads

You have to calculate the area the bolt comes in contact with the frame.

Techno:

Something seems a little funny with your numbers for the strength of a bolt. Firstly - the grade of bolt was not specified, and secondly have a look here.

SS is grade B8(M)

I was using a number from tested 1/2 inch bolts. There are other tests that show the decrease in strength in the thread areas depending on which thread (Course or fine)

Thanks for the great link.

I stand corrected. The value I mistakenly used was a minimum standard for 1/2 Inch anchors imbedded in concrete.

more detail would be helpful dimentions and shape of the item you are hanging would be helpful. what will be in the enclosure? three 1/2 inch bolts should do the trick unless the load is to far from the supporting beam. is the supporting beam or wall strong enough to hold the 70 lbs?

Your question says Calculate shear stress? but there is nothing in the description to indicate why you think the bolts are in shear. As other posts have said, more details needed. Appears to be no problem if load is direct tensile.

Codey