Drilling Deep Holes

[derekdarling]

Pipe makers and Whistle makers make deep holes in wood as a matter of course, and have developed interesting tools to do so. This is one of the easiest tools to make and use for this purpose. Picture courtesy of Mike Nelson, make of Narthumbrian Smallpipes: http://www.machineconcepts.co.uk/smallpipes/tools.htm

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The end of the rod (drill rod, not hardened yet) is ground to a spherical shape, and a hole drilled through from one side to the other. Then the end of the rod is cut or ground off through that hole, leaving a 'D' shaped end. One side will be the leading edge, and the shape creates a great cutting surface. The following edge is ground off a bit, and just the tip hardened. Use the usual tools to hone the leading edge if needed. The half-hole left allows you to grab the swarf as it is cut, to remove it from the hole. The 'Alternate' tip shape serves the same purpose.

The tool is used by first drilling a shallow hole the same size as the drill (DIA 'X"), then inserting the tool, and with a little pressure, turn it by hand. Cut a bit, then remove the tool to clear the swarf, and re-insert for the next bit. The non-cutting end can be ground or filed flat, or shaped however you like. I have seen some users weld a 'T' bar on that end.

Go to Mike's website to get a fuller description,a nd check out his work!

Just thought I'd bring this to your attention.... if you needed to drill a deep hole with incredible accuracy. This tool just doesn't wander once the direction is set.

Derek

[pennview]

Good post about drilling deep holes. I'd add that similar "D" bits can be used in metalworking as well and are somewhat like a spoon bit that fits into a hand brace and used by chair makers.