"Martin Eastburn" wrote in message
...
Do you have a Morse or other taper in the drilling machine ?
if so get a high quality collet holder and double angle insert in 1/8 or
whatever the actual diameter is.

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 to get
out of the nut again. Heck, pretty darn impossible to get into the nut.
The 1/8" I use everyday hasn't been out of the nut since I installed it.
I'm just glad I had spare collet closer nuts on hand when I discovered it.

The big question is the drilling machine has bearings that will keep the
drill stable at speed ?

I spin it at 24K everyday with endmills as small as .026. I figured 10-12k
would be a good starting point for these tiny drills if I can get the feed
right. Torque drops effectively to about zero on this spindle around 8K.

If you don't have a taper in the drilling machine - they make holders with
round shafts.

I was actually looking for one, but so for those I have purchased have been
pretty much garbage. Nowhere near concentric enough. I thought a pin vise
might do the trick, but even if you get the drill engaged with all 4 points
you can see its not straight on those I have tried so far. They tend to be
slightly better with largers bits in the 61-70 ranges, but under 70 they are
crap.

If you get a round shaft with a flat, that flat aligns with a hole in
the chuck if held that way or not on a jaw.

Martin

This application is for venting features in a mold that can not vent to the
parting line. Since its a very soft plastic I plan to drill vent the
features (before cutting the cavity) and blow the holes out with air after
each injection. I can back drill for clearance to the back side of the
plates for a prototype, but if I am successful and wind up producing these
in any quantity the extra setup to do that cleanly will add substantially to
the time and cost.

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 to accomodate the
standard 5/8" injector nozzle for this type application. (1/2+1/2).




On 3/2/2016 11:59 AM, Bob La Londe wrote:
Are there any pin vises suitable for CNC drilling at high speeds for
micro
drills. A high quality high precision pin vise.

I know. I know. Sounds like an oxy moron. I think if I can find a pin
vise that will actually hold the bits straight, and has low enough
runout,
it will be possible with correct speed and feed calculations.

I bought two mid price pin vises from two different sounces, and
unfortunately neither holds a drill bit particularly straight.

In the mean time I ordered some carbide micro drills in the sizes I need,
but because of their DOC capabilities, I'll need to back drill the part.
Oh, joy. A secondary setup for a part what fun. LOL.

FYI: Did some tests with what I had and found HSM Adviser wanted to feed
way to fast. As a check I plugged the same numbers into ME Consultant,
and
it indicated less than half the feed rate of HSM. The HSM numbers flexed
and broken drill bits very quickly. Haven't retried yet with the ME
numbers.