TM 1-1500-204-23-11
Figure 3-13. Typical Drill Reamer Diagram (ST1257B Shown for Reference)
(2) Dagger, Spade, & Brad Point Bits. A dag-
ger, spade or brad point bit are best for drilling aramid
materials as it minimizes iber fuzz (see 3-14, igure
3-15, and igure 3-16). Carbide or Cobalt is gener-
ally the drill material of choice as they hold a sharp
cutting edge signiicantly longer than HSS.
Figure 3-14. Dagger Bit
(a) Spade Bit. The spade type drill was
originally developed speciically for reinforced solid
laminates and honeycomb sandwich panels with clean
entrance and exit surfaces without sacriicial backing.
It can easily be sharpened.
Figure 3-15. Spade Drill for Aramid Laminates
(b) Brad Point Twist Drill. The brad point
twist drill was developed for the wood working industry.
The sharp knife edge cuts the outer hole diameter
with a knife action, the brad point provides good
centering, and the lute-ended cutting surface shears