Cobalt Drill Bit
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Cobalt Drill Bit

Cobalt drill bits, made from heat resistant cobalt steel are heavy duty construction and made to NAS Type J aircraft specifications. Used for drilling holes in hard, tough materials such as stainless steel, titanium high temperature and high strength alloys. High red hardness of cobalt permits speeds 30% greater than HSS drills.

Fractional SizesCobalt Drill Bit

Size Decimal
Equivalent
Flute
Length
Overall
Length
1/16 0.0625 7/8 1 7/8
5/64 0.0781 1 2
3/32 0.0938 1 1/4 2 1/4
7/64 0.1094 1 1/2 2 5/8
1/8 0.1250 1 5/8 2 3/4
9/64 0.1406 1 3/4 2 7/8
5/32 0.1563 2 3 1/8
11/64 0.1719 2 1/8 3 1/4
3/16 0.1875 2 5/16 3 1/2
13/64 0.2031 2 7/16 3 5/8
7/32 0.2188 2 1/2 3 3/4
15/64 0.2344 2 5/8 3 7/8
1/4 0.2500 2 3/4 4
17/64 0.2656 2 7/8 4 1/8
9/32 0.2813 2 15/16 4 1/4
19/64 0.2969 3 1/16 4 3/8
5/16 0.3125 3 3/16 4 1/2
21/64 0.3281 3 5/16 4 5/8
11/32 0.3438 3 7/16 4 3/4
23/64 0.3594 3 1/2 4 7/8
3/8 0.3750 3 5/8 5
25/64 0.3906 3 3/4 5 1/8
13/32 0.4063 3 7/8 5 1/4
27/64 0.4219 3 15/16 5 3/8
7/16 0.4375 4 1/16 5 1/2
29/64 0.4531 4 3/16 5 5/8
15/32 0.4688 4 5/16 5 3/4
31/64 0.4844 4 3/8 5 7/8
1/2 0.5000 4 1/2 6
  1. All dimensions are in inches.

Wire SizesCobalt Drill Bit

Size Decimal
Equivalent
Flute
Length
Overall
Length
1 0.2280 2 5/8 3 7/8
2 0.2210 2 1/2 3 7/8
3 0.2130 2 1/2 3 3/4
4 0.2090 2 1/2 3 3/4
5 0.2055 2 1/2 3 3/4
6 0.2040 2 1/2 3 3/4
7 0.2010 2 7/16 3 5/8
8 0.1990 2 7/16 3 5/8
9 0.1960 2 7/16 3 5/8
10 0.1935 2 7/16 3 5/8
11 0.1910 2 5/16 3 1/2
12 0.1890 2 5/16 3 1/2
13 0.1850 2 5/16 3 1/2
14 0.1820 2 3/16 3 3/8
15 0.1800 2 3/16 3 3/8
16 0.1770 2 3/16 3 3/8
17 0.1730 2 3/16 3 3/8
18 0.1695 2 1/8 3 1/4
19 0.1660 2 1/8 3 1/4
20 0.1610 2 1/8 3 1/4
21 0.1590 2 1/8 3 1/4
22 0.1570 2 3 1/8
23 0.1540 2 3 1/8
24 0.1520 2 3 1/8
25 0.1495 1 7/8 3
26 0.1470 1 7/8 3
27 0.1440 1 7/8 3
28 0.1405 1 3/4 2 7/8
29 0.1360 1 3/4 2 7/8
30 0.1285 1 5/8 2 3/4
31 0.1200 1 5/8 2 3/4
32 0.1160 1 5/8 2 3/4
33 0.1130 1 1/2 2 5/8
34 0.1110 1 1/2 2 5/8
35 0.1100 1 1/2 2 5/8
36 0.1065 1 7/16 2 1/2
37 0.1040 1 7/16 2 1/2
38 0.1015 1 7/16 2 1/2
39 0.0995 1 3/8 2 3/8
40 0.0980 1 3/8 2 3/8
41 0.0960 1 3/8 2 3/8
42 0.0935 1 1/4 2 1/4
43 0.0890 1 1/4 2 1/4
44 0.0860 1 1/8 2 1/8
45 0.0820 1 1/8 2 1/8
46 0.0810 1 1/8 2 1/8
47 0.0785 1 2
48 0.0760 1 2
49 0.0730 1 2
50 0.0700 1 2
51 0.0670 1 2
52 0.0635 7/8 1 7/8
53* 0.0595 7/8 1 7/8
54* 0.0550 7/8 1 7/8
55* 0.0520 7/8 1 7/8
56* 0.0465 3/4 1 3/4
57* 0.0430 3/4 1 3/4
58* 0.0420 11/16 1 5/8
59* 0.0410 11/16 1 5/8
60* 0.0400 11/16 1 5/8
  1. *Not Split Point
  2. All dimensions are in inches.

Letter SizesCobalt Drill Bit

Size Decimal
Equivalent
Flute
Length
Overall
Length
A 0.2340 2 5/8 3 7/8
B 0.2380 2 3/4 4
C 0.2420 2 3/4 4
D 0.2460 2 3/4 4
E 0.2500 2 3/4 4
F 0.2570 2 7/8 4 1/8
G 0.2610 2 7/8 4 1/8
H 0.2660 2 7/8 4 1/8
I 0.2720 2 7/8 4 1/8
J 0.2770 2 7/8 4 1/8
K 0.2810 2 15/16 4 1/4
L 0.2900 2 15/16 4 1/4
M 0.2950 3 1/16 4 3/8
N 0.3020 3 1/16 4 3/8
O 0.3160 3 3/16 4 1/2
P 0.3230 3 5/16 4 5/8
Q 0.3320 3 7/16 4 3/4
R 0.3390 3 7/16 4 3/4
S 0.3480 3 1/2 4 7/8
T 0.3580 3 1/2 4 7/8
U 0.3680 3 5/8 5
V 0.3770 3 5/8 5
W 0.3860 3 3/4 5 1/8
X 0.3970 3 3/4 5 1/8
Y 0.4040 3 7/8 5 1/4
Z 0.4130 3 7/8 5 1/4
  1. All dimensions are in inches.

Drill Feeds & Speeds

Material Hardness Drill Type Point Style Point
Angle
Speed
(SFM)
Feed Coolant
Aluminum / Aluminum Alloys - High Helix Standard 118° 200-300 Medium to Heavy Water Soluble
Aluminum Bronze - High Helix Standard 118° 50-100 Medium to Heavy Water Soluble
Brass, Free Machining - Low Helix Standard 118° 100-250 Medium to Heavy Water Soluble
Bronze, Soft Medium Below 200 General Purpose Standard 118° 70-150 Medium to Heavy Water Soluble
Bronze, High Tensile - Low Helix or Half RD Standard 118° 50-100 Medium to Heavy Water Soluble
Copper / Copper Alloys - General Purpose Standard 118° 100-200 Medium Water Soluble
High Temp Alloys, Cobalt Base 180-300 Cobalt Split Point 135° 5-20 Medium Activated Oils
High Temp Alloys, Iron Base 180-300 Cobalt Split Point 135° 5-20 Medium Activated Oils
High Temp Alloys, Nickel Base 180-300 Nitro® or Cobalt Split Point 135° 5-15 Medium Activated Oils
Iron, Soft Case Up to 150 Heavy Duty or Nitro® Split Point 135° 75-150 Medium Dry / Air
Iron, Medium Case 150-250 Heavy Duty or Nitro® Split Point 135° 50-100 Medium Dry / Air
Iron, Hard Case Over 250 Carbide Standard 118° 40-75 Light to Medium Dry / Air
Plastic & Related Materials - Low Helix Low Angle 90° 100-200 Medium to Heavy Dry / Air
Steel, Low Carbon Alloy 125-275 General Purpose Standard 118° 50-70 Medium Water Soluble
Steel, Medium Carbon Alloy 275-325 Heavy Duty or Nitro® Split Point 135° 40-55 Medium Water Soluble
Steel, High Carbon Alloy Over 325 Cobalt Split Point 135° 30-50 Medium Water Soluble
Steel, Low & Medium Carbon Alloy Below 175 General Purpose Standard 118° 45-95 Medium to Heavy Water Soluble
Steel, High Carbon Alloy 175-225 General Purpose Standard 118° 45-65 Medium Water Soluble
Stainless Steel, Austenitic Below 300 Heavy Duty or Nitro® Split Point 135° 40-60 Medium to Heavy Water Soluble
Stainless Steel, Precipitation Over 300 Cobalt Split Point 135° 20-40 Medium Cutting Oil
  1. Feeds – Feed rates for drilling are governed by the drill diameter, machinability of materials and depth of hole.
  2. Speeds – The speed of a drill is determined by the rate which the outer periphery of the tool rotates in relation to material being cut. In general, the SFM at which a drill will operate is within a range based upon the workpiece material, its condition, hardness and depth of hole. It is usually advisable to start the drilling process at a slower SFM and then increase to the maximum.
  3. RPM = (SFM x 3.82) divided by TD = Revolutions Per Minute
  4. SFM = RPM x TD x .262 = Surface Feet Per Minute
  5. TD – Tool diameter in inches
Cobalt Drill Bit
View
Size Bit Decimal Overall Length Shank Type Item # Availability Price Quantity UOM
Set 1/16 - 1/2 Set w/ Metal Index - Straight DRILSETC In Stock $175.73982/EA EA
Set 1/16 - 1/2 Set w/ Round Index - Straight DRILSETCR In Stock $184.62312/EA EA
1/16 0.0625 1 7/8 Straight DRIL1/16C In Stock $2.25753/EA EA
5/64 0.0781 2 Straight DRIL5/64C In Stock $1.98503/EA EA
3/32 0.0938 2 1/4 Straight DRIL3/32C In Stock $2.22562/EA EA
7/64 0.1094 2 5/8 Straight DRIL7/64C In Stock $2.18391/EA EA
1/8 0.1250 2 3/4 Straight DRIL1/8C In Stock $2.99961/EA EA
9/64 0.1406 2 7/8 Straight DRIL9/64C In Stock $2.84979/EA EA
5/32 0.1563 3 1/8 Straight DRIL5/32C In Stock $3.58252/EA EA
11/64 0.1719 3 1/4 Straight DRIL11/64C In Stock $3.61969/EA EA
3/16 0.1875 3 1/2 Straight DRIL3/16C In Stock $4.47081/EA EA
13/64 0.2031 3 5/8 Straight DRIL13/64C In Stock $4.55985/EA EA
7/32 0.2188 3 3/4 Straight DRIL7/32C In Stock $5.68931/EA EA
15/64 0.2344 3 7/8 Straight DRIL15/64C In Stock $5.5244/EA EA
1/4 0.25 4 Straight DRIL1/4C In Stock $6.21732/EA EA
17/64 0.2656 4 1/8 Straight DRIL17/64C In Stock $7.94553/EA EA
9/32 0.2813 4 1/4 Straight DRIL9/32C In Stock $8.83594/EA EA
19/64 0.2969 4 3/8 Straight DRIL19/64C In Stock $8.45322/EA EA
5/16 0.3125 4 1/2 Straight DRIL5/16C In Stock $9.85898/EA EA
21/64 0.3281 4 5/8 Straight DRIL21/64C In Stock $10.51424/EA EA
11/32 0.3438 4 3/4 Straight DRIL11/32C In Stock $11.36331/EA EA
23/64 0.3594 4 7/8 Straight DRIL23/64C In Stock $13.38102/EA EA
3/8 0.3750 5 Straight DRIL3/8C In Stock $13.42202/EA EA
25/64 0.3906 5 1/8 Straight DRIL25/64C In Stock $15.18159/EA EA
13/32 0.4063 5 1/4 Straight DRIL13/32C In Stock $15.93156/EA EA
27/64 0.4219 5 3/8 Straight DRIL27/64C In Stock $16.6462/EA EA
7/16 0.4375 5 1/2 Straight DRIL7/16C In Stock $18.58108/EA EA
29/64 0.4531 5 5/8 Straight DRIL29/64C In Stock $19.71123/EA EA
15/32 0.4688 5 3/4 Straight DRIL15/32C In Stock $19.58654/EA EA
31/64 0.4844 5 7/8 Straight DRIL31/64C In Stock $20.69727/EA EA
1/2 0.5 6 Straight DRIL1/2C In Stock $23.51258/EA EA
#1 0.2280 3 7/8 Straight DRIL001C In Stock $7.01754/EA EA
#7 0.2010 3 5/8 Straight DRIL007C In Stock $5.23291/EA EA
#11 0.1910 3 1/2 Straight DRIL011C In Stock $4.56279/EA EA
#21 0.1590 3 1/4 Straight DRIL021C In Stock $3.97762/EA EA
#29 0.1360 2 7/8 Straight DRIL029C In Stock $3.23654/EA EA
#32 0.1160 2 3/4 Straight DRIL032C In Stock $2.7677/EA EA
#44 0.0860 2 1/8 Straight DRIL044C 2-4 Working Days $2.3291/EA EA
#55 0.0520 1 7/8 Straight DRIL055C In Stock $2.55596/EA EA
F 0.2570 4 1/8 Straight DRILF-C 2-4 Working Days $4.66848/EA EA
U 0.3680 5 Straight DRILU-C In Stock $16.28378/EA EA