On Fri, 09 Jan 2009 15:54:38 GMT, "Norm Dresner"
wrote:


I've got a bar of aluminum that I had to drill and tap several 1/4-20 holes
in. The bar is roughly 7"x1"x1.25" and drilling and tapping the holes
through the thickness (1") was a good refresher course, but the hole through
the height (1.25") has me stumped.

Nut tap.

McMaster cat# 2583A12
Nut Hand Taps 1/4"-20, 4 Flute, 5" O'all Length
In stock at $40.95 Each

Or for a lot less than $40 you can grind down the shank of a standard
tap by hand. It won't be pretty, but it'll work.

--
Ned Simmons