I use a mill/drill to countersink and a MicroStop countersinking tool
with a pilot pin. I've still screwed up my share of countersink jobs,
however, as it takes but a moment's inattention to cause a problem.
Still, I've had a much higher success rate with the Microstop than with
other tools.
You can find the MicroStop tools at places that cater to the home built
aircraft hobby, such as Aircraft Spruce
http://www.aircraftspruce.com/menus/search.php. Search for MicroStop
model AT442SLS countersink. You will then need to purchase the correct
cutter (both diameter and angle) and the pilot.
The Microstop countersink makes it possible to successfully countersink
with a hand drill, if you are careful, as it ensures that you are (1)
square to the surface being countersunk; (2) coaxially aligned (via the
pilot) and (3) that you stop at the correct depth (via the adjustable
stop, settable in 0.001" increments.) Countersinking a painted surface
also normally requires the no-mar nylon (?) ring for the Microstop for
best results.
That being said, I would use a hand drill only if there were no other
alternative, even with a Microstop, as it's still to easy to mess up a
hole.
A Microstop without any bits and pilots runs about $80, so you are
looking at over $100 for a Microstop, one bit and one pilot.
My K2 still has the stock screws, by the way.
Jack K8ZOA
Jeremiah McCarthy wrote:
Countersinking screws in a home shop without the proper tools can be
frustrating...If you have a drill press and can securely clamp the panel so
that it cannot wander, you might succeed...Even so, the bit itself can flex and
chatter, resulting in a triangular hole...Feeding the bit into the cut very
slowly helps, but it is no guarantee that it will not chatter...
It is next to impossible to countersink holes using a hand held drill motor
even if the panel is clamped in a vise...The cutting angle of twist drills is
not necessarily uniform...It depends on the hardness of the material they were
intended to drill into...Bits bought from surplus clearing houses are sometimes
sharpened to odd angles...
In industry, countersinks have a smooth pilot-pin protruding from the center of
the cutter that is the same size as the screw hole...The pilot bears against
the sides of the hole and keeps the countersink from wandering...These tools
have from 4 to 6 cutting edges, resulting in smooth cutting...Twist drills only
have 2 cutting edges and no pilot and this causes chatter...These countersinks
have a built in adjustable depth controlling device...If you do not cut deep
enough, the screw will protrude above the panel...If you cut too deep, the
screw will seat below the surface of the panel and you will have a silver ring
of bare metal showing all around the screw head...
I would not advise trying to countersink the screws in your prized K-2 unless
you have the tools and the skills...
Jerry, wa2dkg
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