Did you consider using a triple-izer ring? TA makes a 38 or 39 tooth version, that Harris Brothers sells (among other's, I'm sure). I don't know if Willow is still in business, but they made the same thing.
http://sheldonbrown.com/
No need to machine anything, just need a longer BB spindle and (probably) a different rear derailler with greater chain wrap capacity. If aesthetics is a concern, I believe one of these rings hides the granny ring attachment behind the crank arms.
Certainly it's possible to drill a Campy crank to accept a granny ring, I've seen it done. Can't recall ever seeing a D-A conversion, but I don't see why not. Drilling is just more work, and can't be undone, unlike the conversion ring. Your call, of course.
Tom Adams, Shrewsbury NJ
"Charles R Johnston Jr." <crj@frii.com> wrote:
Does anyone remember the post re: making a Campy/Dura Ace double crankset into a Triple ? Think it was within the last year or year and a half. I cannot find it in the archives and wanted to take a look at the setup before I started machining stuff for my D-A conversion. Thanks Chuck Johnston Ft Collins Co.
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