Mayf I'll add one more to the list. The single greatest reason for breaking
small drill bits is ones inability to sense DOWNFORCE! Your sense of touch
is drastically reduced by any kind of drill press or device that increases
the spindle down-force through a rack or gear reduction. You simply can't
feel the stress on the small bit with enough precision to feed the drill at
the correct rate.
The answer is to use an Albrecht spring-loaded hand chuck. It looks like a
pin chuck and is chucked up in any drill press. However, there is a collar
on the outside that stays stationary as you hold it. The chuck turns on the
inside and is spring loaded to translate along the z axis. IOW, the feed is
completely independent from the drill press. You do not run the spindle up
or down. You move the Albrecht chuck up or down with your fingers holding
onto the non-rotating collar. You add the push necessary with your finger
tips! Range is typically about 1/2 in. This is a >must have< item in every
tool box.
Rich Fox "hit the nail on the head" with his recommendation. I think this is
similar. I sent you an eBay link but found this one cheaper after I sent
the eBay information.
http://www.jlindustrial.com/ACS-05570A/SEARCH:CATEGORY/product.html
As previously mentioned, nothing you own will give the correct high speed
for tiny drills. Typical speeds would be 10,000 - 55,000 rpm for the range
of sizes you mentioned. Industrial applications sometimes use air driven
speeders, attached to the quill, to get the correct rpm.
Here is a "rule of thumb" to determine rpm for most machines.
CS x 4 / D = RPM
CS= cutting speed of the material in ft/min (Aluminum is 400)
4 = constant to convert lineal fpm to a rotating diameter
D = the diameter of the rotating item (either the work or the cutter)
-Elon
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