Small hole drilling:

Many machinists and particularly home shop machinists think high spindle speed
is necessary for small hole drilling – they are wrong!

As we all know from drilling larger holes, the drill must (should) remove stock
on every revolution. Feed determines the amount of stock removal. Removing stock
on every revolution is difficult with small drills, #80 or smaller. If high
speed was the determining factor and we ran our spindle at 80,000 to 100,000
RPM, and the drill removed stock on every revolution, we should be able to push
a #80 drill (0.0135" dia.) thru a 0.035" to 0.040" piece of aluminum, CRS or
stainless in less than 2 seconds. We all know that is impossible – the drill
will break first.

When excessive rpm is employed, the drill is gliding over the work surface,
abrading the cutting edge of the drill and at the same time work-hardening the
surface through it must drill.

The solution: use a low rpm and a fast wood-pecker (reciprocating) action – a
delicate touch helps. Also, using the shortest drill for the thickness being
drilled will help along with liberal use of coolant and or cutting oil.

40 years ago National Jet Co. (Najet) was drilling holes in stainless steel down
to 0.001" and smaller at 2500 rpm using a spade drill with a much larger shank
(ground to size as one piece) held in V-blocks and using a rapid reciprocating
hand action machine that they manufactured. They still do it today – using the
same machine. They make their own drills.

Attached are photo's of that machine. I have one.

Neil