On Sat, 17 Oct 2009 17:00:24 -0500, the infamous "Karl Townsend"
scrawled the following:


Rotabroach(TM) or similar annular cutter. Work great, last long time.
http://www.hougen.com/cutters/rotabroach_advantage.html

I've never tried these, but they're similar and are made specifically
for thinner material.
http://www.hougen.com/cutters/sheetmetal/Rotacut.html

I just seen these (see another post). Any reason i can't turn the shank or
make a custom arbor?

I think I'll go this way, just need to figure how to mount it in the radial
arm drill press.

It appears that they're threaded internally, so just make a simple
mandrel for it if one isn't available cheap.

--
The blind are not good trailblazers.

-- federal judge Frank Easterbrook