On Monday, April 6, 2015 at 4:45:22 AM UTC-7, Ignoramus32423 wrote:

If I drill a
1/8" hole, a 6-32 screw taps it for itself very nicely.

Lloyd, I used those holes to mount TO-220 voltage regulator chips, not
for anything structural. worked great!

It'd be better if you used no tapping at all, just a smaller bolt (#4-40).
The force needed to get a #6-32 into an undersize hole can warp the
surface (and hurt the heatsinking). It can also make it hard to stop
when the torque is 'enough': the copper of the heatsink tab can
be deformed, and that makes for a TERRIBLE thermal connection.