Standard — This is the most common flute design, with 30° Helix angles
Parabolic Design (often called deep hole jobbers) – usually 40° Helix angles, the open design helps chip removal out of the hole. These are especially effective in very soft materials like plastics and aluminium’s.
DRILL POINT ANGLE DESIGN FEATURES
118º Standard is found on most common drill types. 135º Self-centering (split point) enables faster starting and cutting actions, especially in hard steels and stainless steel.
Use the shortest drill possible as shorter drill bits are more accurate and because they’re more rigid they don’t break as often, Shorter drill bits are also better in confined spaces.
Dills are often described by their length, referring to the effective flute length or maximum drilling depth in relation to the diameter.
For example: Jobber drill length drills are 5xD, this means a 5mm jobber drill would have an effective drilling depth of 25mm.
Stub Length: 3XD
Jobber Length: 5XD
Long Series: 8XD
Taper Shank: 5XD
Long Series Taper Shank: 8XD
Reduced Shank: 5XD (However, usually share a common length of roughly 6" (152mm) overall length with a 3-3/8" (86mm) flute length)
- For hard to machine materials, interrupted cutting or unstable setups a reduction of feeds and speed of 50% may be required.
- When drilling using Hand held Drill machines, Rpm may need to be reduced as feeds are being applied manually. This may help prevent excessive wear and work hardening of materials.
- Always opt for a lower starting RPM and increase as required
- If using set machine selectors always select the lower option first
METRIC/IMPERIAL CONVERSION CHART