Need Help!- Tiny Holes, Lots of Em!

[ServoGuy]

Hello,
I have a bit of a technical question here.
I plan on making a good number of parts that have a lot of tiny holes in them,
and it is absolutely critical that I get no bit breakage per part. A bit stuck in the part would ruin it completely, and tragically that happens more often then not.

I would like to know what the best feeds and speeds and RPMS for the following:
I plan on using peck drilling, G83 I think. The tiniest bit is the one I am having the most trouble with.

Material: Brass, yellow.

Drill: 0.028 (HSS, unless it would be better for something else)
Depth: 0.375"
Number of holes: 72

Drill: 0.042 HSS
Depth: 0.375"
Number of Holes: 36

Drill: 0.0625 HSS
Depth: 1"
Number of Holes: 36

Machine: Tormach PCNC 770,
Flood Coolant - the blue stuff

I have tried with the tiny bit 0.5IPM feed, 0.02 Peck, 2400rpm, full retract
Works, sometimes.

Any help would be greatly appreciated!

[Geof]

Yellow brass can be a bit of a problem with standard helix drill because brass tools should have zero top rake and the cutting edge on a drill doea have top rake due to the helix. On larger drills it is possible to hand grind a small flat on the edge to get zero rake and this helps but you would need a steady hand on the size you are using.

You may be able to get drills intended for brass with a reduced helix.

[neilw20]

Run faster maybe.
I would think maybe 4000 or more.
Then the 0.5IPM will be closer to right.
Imperative to spot center first. If not spot on, the drifting drill will break.
I do spot centering with the same program, but just use Z-inhibit to limit the depth with the center drill.

[packrat]

You don't really need to use a grinder to blunt the lip edges of the drill, using a stone and giving a few swipes on each lip is enough on small drills like this.

cary