0.225 sq inches?
 

I just spent a few minutes in AutoCad and came up with 0.225" square inches. Just wondering how close I'll be to your number. Obviously yours should be more exact. But, imho, the pic still wasn't sharp enough. I was guessing where the outline was in a few places.

http://www.ferdster.com/forum_attach...od_autocad.jpg

--Ferdi

Y8S is right. The correct way to talk about failure due to too much power (power stroke pressure in the chamber -> pushing on the piston -> pushing on the rod) is buckling, which is why I mentioned Euler column buckling above. Static assumptions with pinned ends might be a decent assumption but I would think that the dynamic loads could add significant side loading that would reduce the calculated failure load.

For any of this, correct material properties (alloy, heat treat) are needed.

I learned about buckling the hard way. In Intermediate Design in college. We had to build truss structures out of steel straps and bolts that supported a known qty of weight before failure.

not only were our calcs way off, but the thing held all the loose objects in the room and never did break. it bent to shit--buckling.

or just spend $300 or whatever and get the CAT/Eagle/Probe rods everyone else is using. Unfortunately it looks like I'm the lab-rat for tracking these. Pick your fucking battles on saving money...I'll drive my shit home.