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Re: Antenna research
>Trivia question for tool-types:
>I remember that in the Ag Engineering machine shop, they had some two-
>piece dies to make holes through sheet metal. You drilled a small
>hole for a bolt connecting the two pieces, which were round cup-
>spaned dies. The smaller fit inside the cavity of the other, and had
>cutting edges. The basic technique was to drill a small hole
>through the metal for the bolt, connect the dies with the bolt, then
>tighten the bolt, and the smaller die but thru the sheet metal while
>being braced against the larger die on the opposite side of the
>metal. No warping, no slipping.
>ASCII art attempt: __________
> | | Large die
> | |
> |______| Small die
>Anyone know what those dies are called?????? Maybe I should call dad
>and see what's happenin'......cheers.
These are called Knockouts, or Knockout punches. Industrial electricians
use them routinely to make holes for conduit in breaker boxes, etc. A well
equipped tool shop ought to have 'em. You may find them at local electrical
supply houses, too.
BTW, if you can find a set to borrow, make sure they're sharp, as they can
misbehave and leave jagged edges if dull or burred.