Tim Wescott wrote:
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.

must the hole be round?

if not, drill a crappy hole with a trist drill and then tear the rest size
with good needle nose pliers.

I've opened canned food with needle nose pliers, so I know they can cut
such metal pretty nicely.