"Tim Wescott" wrote in message
...
I've got a little 3oz fuel tank (model airplane) made out of thin
tinplate (a Dole Pineapple Chunk can, actually). So, maybe about 10
or
15mil, with corrugations.

I need to drill a 1/2" diameter hole in it, to solder in a fitting.
I
know that if I use a regular 1/2" twist drill I'll just rip out big
hunks
of tin -- so that's a no-go.

This is a last-minute rework to get me to a contest this weekend,
and
I've spent out the modeling budget this month. So I'd like to be
able to
do it with tools I have in the shop rather than spending time or
money I
don't have to order something, or even nip around to Horror Freight.

I have a nice stepped drill that goes up to 1/2 inch, but it's
longer
than the tank. I may just go ahead and drill through and patch up
the
far end -- but if there's a better solution, I'm open to
suggestions.

A 1/2" one-flute countersink may do the job well enough.
http://aeroconsystems.com/misc/rattpak_countersink.jpg

You could turn your own one-step drill bit from drill rod. Mill 1/4 to
1/2 off of it with an end mill to get a radial cutting edge. It might
drill the can without hardening.

I made an emergency one to open up truck spring u-bolt holes from 1/2"
to 5/8", so the kid could get his truck back together and out of my
driveway. It was milled half-round and definitely did need to be
hardened, twice to get it right.

jsw