Steven, By far the easiiest way, simple enough for a home mechanic, is to beg, borrow, or whatever a NR triple crank, or other triple crank that uses a 144 bcd for the middle and outer rings (e.g., Avocet), and bolt it back-to-back to your NR double, using it as a template. It's easy then to locate the centers, and drill away. Mike Barry has done a number of these. I have a couple. Lacking a triple crank, I guess you would have to create a template, perhaps using chainrings for patterns, which certainly complicates things and may be best left to a machinist.
All the best! Gary DellaRossa, "finally above freezing," Toronto, Canada,
>From: "The Maaslands" <TheMaaslands@comcast.net>
>To: "CR" <Classicrendezvous@bikelist.org>
>Subject: [CR]converting NR cranks to triple
>Date: Mon, 12 Mar 2007 01:22:47 -0400
>
>I have a friend in Italy who would like to convert a Campagnolo NR crank
>to a triple. If I remember correctly there was a list member who was
>willing and able to do this.
>
>I f anybody has experience with this and can give me any indications, I
>would be appreciative.
>
>Thanks,
>Steven Maasland
>Moorestown, NJ
>USA