For my sins I just went to B&Q for a bit of steel and ended up with 1 metre
of 10mm(ish) threaded rod as it was the biggest solid rod that they had
that would still fit my drill chuck.

I used my plumbing blowtorch to heat it and after a bit of hammering,
grinding and tempering it looked like this.

http://i1052.photobucket.com/albums/...914C56A8A7.jpg

http://i1052.photobucket.com/albums/...913E7A1EE2.jpg

A bit rough but I had a go at drilling a hardwood log that was about 3"
thick and it made light work of that.

http://i1052.photobucket.com/albums/...91462D39C7.jpg

So, a good result and easier than I thought it would be. Also an awful lot
cheaper! Sadly, it turns out that it's no use for the job I had planned
for it (just can't get the angles right to drill through the things I want
to drill through without going through the roof) but that's not a fault of
the drill, just the geometry of the location that I'm dealing with.

My thanks to Colin Bignall for the suggestion.

Tim