View Full Version : 304 S.S. alloy drilling question

10-15-2002, 01:05 PM
Can 304 alloy S.S. (11 ga. sheet) be drilled easily (non-production, only home shop use) with HSS drills or do you need coated bits?


NRA Lifetime Member

10-15-2002, 09:40 PM
I've drilled heavy 308 and 304 with standard hss bits they work fine. If you lessen the angle some it is better (instead of 60 degree.)

10-16-2002, 12:19 AM
Use a 135* split point in HSS. The web on Cobalt drills is too thick and work hardens the SS too much. A good 135* Split point is God's gift to those of us who like shiney things. BTW, don't waffle on the feed, constant feed pressure is required or, (SUrprise!) you will work harden it even more.

10-16-2002, 12:33 AM
Ditto to Thrud's post....

and yes... http://bbs.homeshopmachinist.net//redface.gif I to have the need for things all shiny http://bbs.homeshopmachinist.net//biggrin.gif

10-16-2002, 06:33 PM
Thanks for the info, one less thing to plan for/buy.


10-17-2002, 09:00 PM
One more thing....

(if you're going to use HSS and lean on the cut)

Watch your heat. 304 will get your drill hotter than holy hell, really fast. Maybe try some water-based sauce. You'll probably find that you'll be rounding off your cutting edges before you work-harden the bottom of the hole (although Thrud will probably say that's why).

I use water on HSS and Tap Magic on cobalt...that seems to be the ticket, at least at my machine...

Forrest Addy
10-17-2002, 09:08 PM
A couple more final things:

Stainless work hardens don't let the drill dwell in the work. Keep the chips flowing.

I like a rich (1 part oil to 5 parts water) mix of soluable oil froma laudry squirt bottle for drilling stainless. It's the best of both worlds: you have the water for cooling and the oil for enhancing the cutting action.