I sometimes have a hellava time mounting a drill press to a vehicle or fence
post, etc.
Having a set of split-point drills up to 1/4" or larger can be very
worthwhile in the workshop for pilot holes, drilling with a hand drill or
drill press.
Pilot drilling with a drill diameter of approximately the thickness of the
larger drill's web, makes metal removal very fast and nearly effortless.
Split-points have no chisel edge in the web, and they begin to cut as soon
as they contact the workpiece.. where common twist drill points require
force to make the drill displace metal in order to cut.
The rotational cutting rate of the center of a commonly ground drill point
is zero FPM.
Split-points are very pactical, but a lot of folks believe they require
special equipment or skills to create or sharpen them, but they don't.
Split-points can be ground on any common twist drill with a bench grinder,
by grinding a low angle flat on the back side of the flute (almost parallel
to the cutting edge, and almost parallel to the twist spiral), followed by
grinding the cutting edge relief in the conventional way.
This procedure can be clearly seen by closely examining a factory-ground
split-point drill.
--
WB
..........
"Robert Swinney" wrote in message
...
Don sez,
some snip and,
"And in particular, I would go for split points instead of the
usual chisel points."
Don, as usual, I agree with your basic suggestions but I fail to see the
facility of split points
for the basic home-shop craftsman. Most of us use drills in machine tools
and thus the necessity
for easier penetration of a split point is not a big factor.
Bob Swinney
"DoN. Nichols" wrote in message
...
On 2010-05-24, Howard Eisenhauer wrote:
I'm in the market for a completes set of numbered bits to replace the
cheap Chinese set Ii bought a few years ago (a lot of the smaller ones
were actually the same size :/)
Who makes the best set? I don't mind spending the money for good
ones.
Given my choice -- Cleveland or Chicago-Latrobe.
If you don't need the extra length of the jobber style, I would
go for the screw machine length ones.
And I would go for high Cobalt steel instead of just plain HSS.
And usually bright finish.
Of course, all those selections lead me down to only one (in the
Chicago-Latrobe brand -- Cleveland does not even fit those selections)
-- MSC # 81109589 at $175.21 unless you catch them on a sale someday. :-)
The only other two which fit all of those selections are by
Hertel at $141.72 and "Precision Twist Drill" at $181.13. At those
prices, those other brands should be pretty much the same quality.
Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---