Drill sizes

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

wktaylor

Well-Known Member
Joined
Sep 5, 2003
Messages
285
Location
Midwest USA
Cobalt-steel or titanium-nitride-coated HSS will last indefinitely for drilling aluminum... unless abused.

The actual specifications for aircraft/US [Inch] drill bits are...
NAS907 Drills, High Speed Steel and Cobalt, 1/16 Inch thru 1/2 Inch
NAS937 Drills, Double Margin Stepped, High Speed Steel and Cobalt, 1/8 Inch thru 1/2 Inch
NAS965 Drills, High Speed Steel and Cobalt, Threaded Shank, 1/16 Inch Thru
NAS988 Drills, Carbide, Double-Margin, 1/8 Inch thru 1 Inch
ASME B94.11 Twist Drills
A good spec to have at hand is... AND10387 Drill Sizes and Drilled Hole Tolerances - Twist

Sources for aircraft drill bits... NOT promoting any one site... just-to-name-a-few... probably dozens more...

ATS - Aircraft Tool Supply Company Aircraft Tool Supply Company
BrownTool Brown Aviation & Aircraft Tools
ATI Tools ATI® Tools - Airframe Tooling for Production & Maintenance
Dreamer combination drill Bits Dreamer Cutting Tools, Inc.
Grainger https://www.grainger.com/
MSC Direct MSC Industrial Supply - Metalworking tools and MRO Supplies
Yardstore Yardstore - Aircraft and Aviation Sheet Metal Tool Supply
US Industrial Tool & Supply Company Metal Working Tools | Metal Shop Tools | US Industrial Tool - U.S. Industrial Tool
 

Attachments

Angusnofangus

Well-Known Member
Joined
Sep 29, 2015
Messages
481
Location
Victoria, Canada
Cobalt-steel or titanium-nitride-coated HSS will last indefinitely for drilling aluminum... unless abused.
Personally, I was never a big fan of cobalt drill bits over HSS, they didn't seem to last any longer and they are about three times the price. You can drill 2024-T3 a looooong time with HSS, but the real test is when you use that same bit on 7075-T6. That's when you know for sure that it is dull.
 

wktaylor

Well-Known Member
Joined
Sep 5, 2003
Messages
285
Location
Midwest USA
I thought this visual guide of drill-bit point angle might also be useful...

135+/- and 118+/- Degree are 'standard drill-point angles for steel/CRES and aluminum drilling... but tip angles are shown for best drilling other metals, wood, rubber and plastics, etc. BTW... this assumes VERY sharp cutting edges to points and flanks.
Which Drill Point Angle Should I Use~Drill-Bit Tip Geometry.png

Article... Which Drill Point Angle Should I be Using? | Regal Cutting Tools
 
Last edited:
Top