Compressive stress of bolts? 1

[kingnero]

I like to use four bolts for setting a heavy workbench level.
For this I would need four pieces of steel, drilled and tapped for the bolts, welded on the bottom of the feet.


Can I use (100% of) the yield stress for this (for the grade of bolt I'm using), or would this not be correct?
Now that I think of it, I've never calculated a bolt for compression. Not even a set screw.

Also, what would an appropriate factor of safety be?

I appreciate your input...

 

[kingnero]

I should have taken my notes before asking this here.

The formula rb1957 has provided, had me remind where I could find the necessary info for this.

Method:
Choose bolt and length in such a way that Lambda (slenderness ratio) gets under 20.
You do so by choosing a certain length, than calculating euler length (pinned - fixed as suggested above), and calculating I from the inner circular rod (that symbolises the bolt minor dia).
Lambda = Euler length / i
with i = sqrt(I/A)

When lambda < 20, you only have to worry about compression force and thread shear.

Compression force should be smaller than 90% of yield strength (using correct units of course).

Engagement length and thread shear as explained in Bickford's handbook.

Done.
Thanks all for your replies.