Need Help!- Drilling 303 SS

[Gerdy]

I need to drill 1/8" dia 4" deep into a 5/8 dia 303 SS Any suggestions? I have a CNC Lathe and Mill would one be better than an other?

[BobWarfield]

Gerdy, that hole depth to diamter ratio is going to make it a bear no matter which way you go.

I'd be tempted to go with the lathe just to get the hole horizontal to help the chips come out, sort of like horizontal mills clear chips better than verticals.

You're either going to have to get with the tooling suppliers to find the magic drill to work or attack the hole from 2 sides. If it isn't a through hole, no joy for 2 sides.

A drill with parabolic flutes will help on a hole that deep.

Best,

BW

[Gerdy]

Thanks... can only do from one side. I'm new here, is there a forum to ask someone about special tooling?

[dertsap]

how about using a gun drill ?

[DSIF]

First the good. 303 is butter as far as stainless goes. The bad-you are drilling 32x the dia. of the drill. My 2 cents...
1)#2 C/D @60 SFM Z-.060
2)1/8 jobber drill as far as you can go
3)Taper L. drill @ 50-60 SFM as far as you can go
4)Aircraft drill @ 50 SFM to finish the hole.
Do this on your mill. Turn down the rapid and the coolant pressure. Drill at @ 2.0 IPM down deep,.040-.050 per peck.
PS: Break it off in your customer!
Dan

[Gerdy]

Thanks for the help.