On Thursday, March 3, 2016 at 3:32:40 PM UTC-5, whit3rd wrote:
On Thursday, March 3, 2016 at 9:36:02 AM UTC-8, Bob La Londe wrote:

This machine has an ER11 spindle nose. I would just get ER11 collets for
each drill size, but anything under 1/8" is pretty much impossible

This application is for venting features in a mold...

Carbide 1/8" shank drills will only take me down to a depth max of about
3/8". Less on smaller bits. The plates are 1/2" thick

But you indicated this was for NC machining? So, can you pre-drill 0.250"
deep with a 0.130" diameter bit, then sink the microdrill the rest
of the way? I foresee some chip clearance issues still, but pecking
might work.

Great idea, with some changes for drill bits you can actually buy. With a drill such as http://www.mscdirect.com/product/details/71465157 you could drill .130 dia .320 deep, hold .980 of the bit's shank in the collet and drill the remaining .180 and still have .010 clearance between the collet and the work, and .010 of flutes left over.

Probably better to drill the shank clearance holes as deep as possible, minimizing the depth of the tiny hole. There is a LOT of shank available (1.31") on these drills.