Hollow drills

Ron Nossaman nossaman@southwind.net
Tue, 06 May 1997 10:03:54 -0500 (CDT)


Hi all,

In a pinch (needed one NOW), or if you need a smaller size than is commercially available (had a rash of broken BRIDGE PINS in a church piano once, broke just below the bridge surface), make what you need.

Get a length of water harden, rather than oil harden, drill rod of the appropriate diameter from an industrial supply. Cut off a two inch length, or so, and save the rest for the next time. Square the ends up on a bench grinder, and chuck it in a drill pr
ess. Put a center drill in the drill press vise, set your speed to low, and center drill both ends of the piece. If you've never done this, you are in for a treat. Feed the work slowly down on the center drill with one hand, centering the bit underneath b
y feel. If you're careful, it will center nearly automatically. Exchange the center drill with a jobber's bit of appropriate size, and drill clear through the length. You might have to sneak up on it with multiple passes of increasingly larger bits to rea
ch the final size, depending on what the final size is. This material, although unhardened, is pretty tough.

Grind or file whatever you want for teeth, a Dremmel cutoff wheel is a "quick and dirty" for this one. Harden it, or not, as you wish. Unhardened, it will get you through a lot of holes with an occasional tooth sharpening. Hardened, the teeth hold an edge
 better but you'll more probably break it and be making another one. Hardening consists of heating to bright cherry and water quenching. Tempering afterward (heating to straw color and quenching) makes it less brittle, but is a touchier process.

If you have the tools, it's worth the fifteen or twenty minutes if you need it immediately, or are the pathologically independent type. <G>


 Ron Nossaman




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