<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF"> Apprappo the area moment of inertia.  This is the one Ron N brought in a couple weeks back in the hammer shank stiffness thread isnt it ? Thanks for the link. This was a new one on me. Might be fun to see where this takes us with all these different hammershank shapes and sizes. Cheers RicB "Don A. Gilmore" wrote: <blockquote TYPE=CITE><style></style> Hey Jude: The area moment of inertia is only dependent on the crossectional shape and size and not on the material.  So if you can find a standard set of formulas, they are good for any material.  Most common crossections are here: <a href="http://www.efunda.com/math/areas/Common_Geometric_Shapes_Index.cfm?search_string=moment%20of%20inertia">http://www.efunda.com/math/areas/Common_Geometric_Shapes_Index.cfm?search_string=moment%20of%20inertia</a> You can also easily calculate compound crossections made up of any combination of these fundamental ones.  I can show you how to do that too, if you're interested.  The units should come out in "length to the fourth power", like inches^4, or m^4.  Be careful not to use the "mass" moment of inertia as that is used for dynamic calculations and is in units like lbm-ft^2, slug-ft^2, or N-m^2. One psi = .0703 kg/sq.cmOne kg/sq.cm = 14.23 psi. I don't think I understand your angle question.  60' should mean "sixty arc-minutes", which is one degree.  What does your jig look like? Don A. GilmoreMechanical Engineer</blockquote> -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>   </body> </html>