Hiya,

Long time no speakee...i have a challenge & you guys popped straight into my non engineering mind!

I seek to be able to drill a hole about 4mm diameter, very accurately (ie no divergence) all the way along a 450mm long guitar neck...



....so that the resulting bored hole runs just beneath the fretboard (the fretboard is the 3mm veneer dark wood on top of the neck ie where where the guitar puts his fingers)

Two problems...

1. What kind of custom rig would be in order (I'm thinking any drilling bit/rig would need to 'hang' vertical so gravity doesn't 'pull' on the bit, causing it to diverge)

2. Where on earth could I buy a drill bit just 4mm diameter and 500mm long! (or how would you approach making one?!). I have found places that sell 500m bits, but they start at 6mm diameter, which is excessive for my needs.

Things to consider....

No snappage - it would be catastrophic to have the bit snap half way along

Really accurate - it would be even more of a tragedy to see the drill bit surface out of the guitar's fretboard at the end of its travel!

repeatability - I'd like to do this to a few necks!

Many thanks,

Hank.