Twist Drill Bit

Terminology for multi-facet grinds

General Guidelines for 4-Facet Grind
Drill Bit SIze Point Angle Clearance Angle Notes
Inch
Decimal
Inch
Fraction
Metric (mm) Wire Number Letter Mild Metal, Wood Hard Steel
< 0.125 < 1/8 < 3.0 > 31 118° 14° 11° Can't use the Tormek DBS-22 Drill Bit Sharpening Attachment with these bits -- they are too small. However, one sharpener has used a precision pen vice (like the Starrett 166C ) with the Tormek DBS-22 to hold bits as small as #61 (5/128 in. / 1 mm).
0.125 - 0.250 1/8 - 1/4 3.0 - 6.0 31 - 1 A - E 118°
14°
11°
Bits as small as 1/8 inch can be held in the Tormek DBS-22, but they can flex easily. A pin vice can assist with reducing this flex.
0.250 - 0.500 1/4 - 1/2 6.5 - 12.0 F - Z 118°
11°

0.500 - 0.875 1/2 - 7/8 12.5 - 22.0 118°


> 0.875 > 7/8 > 22.0


Can't use the Tormek DBS-22 Drill Bit Sharpening Attachment with these bits -- they are too large

Material-Based Guidelines
Material Type Point Angle Clearance Angle Notes
Recom. Range Recom. Range
Aluminium 118°
90 - 130°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Armour Plate 135°
135 - 140°

6 - 9°
Brass 118°
118°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Bronze 118°
110 - 118°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Bronze, High Tensile 105°
100 - 110°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Cast Iron, Soft 95°
90 - 100°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Cast Iron, Medium 105°
100 - 110°
(as above)
12 - 15°
Clearance angles based on drill bit size should be used.
Cast Iron, Hard 110°
100 - 118°

8 - 12°
Cast Iron, Chilled 118°
118 - 135°

5 - 9°
Copper 118°
100 - 118°
14°
12 - 15°
Iron, Malleable 95°
90 - 100°
14°
12 - 15°
Magnesium and Alloys 95°
70 - 118°
14°
12 - 15°
Monel Nickel 120°
118 - 125°
11°
10 - 12°
Nickel Alloys 135°
135 - 140°

5 - 7°
Plastic, Hot Set 90°
60 - 90°
11°
10 - 12°
Minimum point angle on the Tormek DBS-22 Drill Bit Sharpening Attachment is 90°.
Plastic, Cold Set 125°
118 - 135°
14°
12 - 20°
Steel, Low Carbon 118°
110 - 118°

7 - 9°
Steel, Medium Carbon 118°
118 - 125°

7 - 9°
Steel, High Carbon 130°
118 - 145°

7 - 9°
Steel, Forged 130°
118 - 145°
11°
7 - 12°
Steel, Alloy 118°
118 - 125°
11°
10 - 12°
Steel, Stainless 115°
110 - 118°
11°
8 - 12°
Steel, Stainless, Hard 125°
118 - 135°

6 - 8°
Steel, Manganese 145°
140 - 150°

7 - 10°


Notes & Comments
Information regarding Grindstones


Good videos showing the use of the Tormek DBS-22 Drill Bit Sharpening Attachment:

Tormek Live Sharpening Class - Part 6 - Drill bit sharpening

It's time for drill bit sharpening! Learn how to sharpen your drill bits with maximum precision, to the greatest sharpness. We will show you how to create a 4-facet point which gives the ideal cutting performance.

Sharpen drill bits with Tormek Drill Bit Sharpening Attachment
Tormek DBS-22
Tormek Drill Bit Sharpening Attachment


Tormek is a copyrighted logo of Tormek AB. Its presentation on this site is used to help the user quickly understand when specific Tormek tools, jigs, or setting are being used. For specific information regarding Tormek AB, or its products, please refer to the www.Tormek.com.


About this site
Remember : The goal of sharpening is to produce sharp tools, and these tools can injure you if mishandled. Safety measures should be followed to protect yourself and those in your shop. Be sure to read and follow all instructions from the manufacturer, and and utilize proper safety equipment. Never consume alcohol or anything that could impair your judgement before sharpening tools, or using sharp tools. Comments can be sent via eMail to me at SharpeningHandbook@Gmail.com.