On Wed, 18 Apr 2012 18:15:01 -0400, Jim Wilkins wrote:

"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

Thank you. I happened to have one, and it made a nice clean round hole
-- just like I wanted. My ass is saved -- for the moment.

It's one of those head-smackingly obvious things in hindsight, isn't it?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com