Maybe some of youse guys will remember the Avocet crank sets made by Ofmega I think) in any case, they had an interesting treatment at the outer edges of the crank spider arms. On the inside of the squarish outer edges, they have a 2-3 MM deep groove machined along the edge to allow clearance for the 41 T chainring.
On Campag cranks that use a 41 t ring, I have noticed the chain will chew that area along the spider ends.. Not tidy at all.
Dale Brown