Can I pick your brains? How would you solve this puzzle....

[BillTodd]

Robin has it bang on (saved me a lot of typing :)) gun drills only work because the job is spinning.

That said: I think, with the right technique, you could drill 500mm into a soft-ish material without too much drift.

First, grab yourself some wood of the same type as the neck to practice on.

Use a sequence of drills each a 1/2 mm or so smaller than the last. (you might be able to do it with one drill, but that doesn't give you the option of 'correcting' the path slightly)

Fix (braze or silver solder) the smaller drills into the end of steel rods the diameter of the previous drill. (concentricity is obviously important, as is a correctly sharpened drill).

I've drilled an 8" deep blind hole in steel using this technique with a 4mm jobber bit that was just a press-fit into the end of a silver steel rod ( [edit]I pinned it to the rod to stop the drill turning)

The first drill hole is the most important. Make a sequence of sleeves to align the rod in the first hole, so the drill is guided for its whole length.

Drill using lots of pecking (3-6mm in, then pull out and clear the chips) .

If you don't have a long bed lathe handy, then some kind of long sliding rig is essential.

It's a difficult, not an impossible job.

Bill