On 28 Oct 2006 21:26:12 -0700, wrote:

...
Perhaps that's the case. My router book says that 3/8" collets aren't
included much any more, though. Maybe it's metric?
...

Entirely possible. Quoted from Wilkipedia:

Many routers come with removable collets for the popular shank sizes
(in the USA 1/2in and 1/4in, in Great Britain 1/2in, 8 mm and 1/4in and
metric sizes in Europe - although in the United States the 3/8-inch and
8 mm sizes are often only available for extra cost).

Ref: http://en.wikipedia.org/wiki/Plunge_router


It also mentions 10mm and 12mm sizes.