12 Pcs. IMPORTED 1/4" COBALT Fractional Jobber Drill (135 Deg.). Manufactured to National Aerospace standard 907. Made of heat resistant cobalt, they display higher red hardness which permits speeds upto 30% greater than high speed steel drills and are especially effective in drilling tough, high tensile strength materials like PH stainless steel, inconel, and titanium. The 135 Deg. split point is self-centering and reduces thrust. Sizes smaller than 1/16" have the 118 Deg. standard point.
Technical Specification:
- SIZE : 1/4"
- DECIMAL EQUIV. : .2500
- FLUTE LENGTH : 2-3/4"
- OVER ALL LENGTH : 4"
FACTORS THAT INFLUENCE DRILLING:
When selecting or designing drills for today's materials and equipment, there are a number of factors that will influence your choices. These choices will determine the success or failure of the drill. Here are the three basic factors to consider:
1. Depth of Hole
2. Feeds and Speeds
3. Fixturing
1) Depth of Hole:
In selecting a drill, one of the factors to consider is hole depth. The type of drill to apply will be determined by drill design. In sonsidering hole depth, four drill design features require examination. These include:
Web Thickness
Web Increase
Flute Form
Point Style and Geometry
2) Feeds and Speeds:
In Calculting feeds and speeds, consider the following:
Material -
Material will determine the surface feet or revolutions per minute (RPM's).
Ductility of Material -
Ductility of the material will determine the feed rate for ease of chip formation.
BHN Briness Hardness -
Hardness along with ductility will determine the base tool material for the drill.
3) Fixturing:
Three elements of fixturing are important to successful drill performance. These include: rigidity, clearance for chips and passage for cutting fluids.
A)Rigidity -
With regard to rigidity, ask the following questions:
Does the part move in the fixture?
Is the fixture mounted properly?
Does the spindle have axial or radial play?
B)Clearance for Chips -
Chip clearance is critical and the following needs to be assessed:
Is there sufficient room for chip evacuation?
Is the bushing the proper length? (Approximately 60% of drill lead)
Is the bushing positioned on the part or is there clearance between the bushing and part to allow for chip evacuation?
C)Passages for Cutting Fluids -
With regard to the use of cutting fluids, the following two inspections need to be made:
Are there sufficient coolant lines?
Are the coolant lines directed to the proper locations?
Drills are sold in Package Quantities Only!
Please see the Package Chart on the Bottom of this Page.
See our Ebay Stores for Individual Quantities and Prices.
Fractional Jobber Drills
|
|
Size
|
HSS Import
|
HSS USA
|
Cobalt Import
|
Cobalt USA
|
Precision Twist Drill-M42
|
|
1/64"
|
$4.80
|
$12.00
|
$15.48
|
$19.92
|
$36.84
|
|
1/32"
|
$3.00
|
$9.00
|
$12.36
|
$15.84
|
$28.56
|
|
3/64"
|
$3.00
|
$9.00
|
$9.12
|
$11.64
|
$21.36
|
|
1/16"
|
$3.00
|
$6.00
|
$8.64
|
$10.20
|
$19.92
|
|
5/64"
|
$3.24
|
$6.00
|
$8.64
|
$10.20
|
$20.28
|
|
3/32"
|
$3.24
|
$6.00
|
$8.64
|
$10.20
|
$19.92
|
|
7/64"
|
$3.24
|
$6.00
|
$9.12
|
$10.68
|
$21.36
|
|
1/8"
|
$3.24
|
$6.00
|
$11.28
|
$13.08
|
$25.44
|
|
9/64"
|
$3.84
|
$6.60
|
$11.28
|
$13.08
|
$25.68
|
|
5/32"
|
$3.60
|
$6.60
|
$12.60
|
$16.08
|
$28.68
|
|
11/64"
|
$4.20
|
$7.20
|
$13.32
|
$17.04
|
$30.24
|
|
3/16"
|
$4.44
|
$9.00
|
$14.88
|
$19.08
|
$33.96
|
|
13/64"
|
$5.28
|
$9.00
|
$17.88
|
$22.44
|
$40.92
|
|
7/32"
|
$5.40
|
$9.60
|
$19.56
|
$25.44
|
$44.64
|
|
15/64"
|
$6.00
|
$10.80
|
$20.76
|
$26.76
|
$47.52
|
|
1/4"
|
$6.24
|
$10.80
|
$22.20
|
$28.08
|
$50.40
|
|
17/64"
|
$7.80
|
$17.40
|
$25.08
|
$32.28
|
$57.60
|
|
9/32"
|
$7.68
|
$18.00
|
$26.40
|
$33.84
|
$60.24
|
|
19/64"
|
$9.48
|
$9.00
|
$16.02
|
$20.58
|
$73.44
|
|
5/16"
|
$9.72
|
$10.50
|
$17.10
|
$21.96
|
$39.06
|
|
21/64"
|
$11.40
|
$12.00
|
$18.90
|
$24.30
|
$43.26
|
|
11/32"
|
$12.12
|
$12.00
|
$20.70
|
$26.58
|
$47.46
|
|
23/64"
|
$14.28
|
$13.50
|
$23.82
|
$30.60
|
$54.54
|
|
3/8"
|
$14.04
|
$13.50
|
$23.82
|
$30.60
|
$54.12
|
|
25/64"
|
$16.80
|
$15.00
|
$27.06
|
$34.74
|
$61.98
|
|
13/32"
|
$8.22
|
$16.50
|
$28.26
|
$36.30
|
$64.74
|
|
27/64"
|
$9.72
|
$17.10
|
$31.20
|
$40.14
|
$71.46
|
|
7/16"
|
$9.66
|
$18.00
|
$31.92
|
$40.98
|
$73.14
|
|
29/64"
|
$11.10
|
$19.50
|
$38.28
|
$49.20
|
$87.78
|
|
15/32"
|
$11.28
|
$21.00
|
$39.00
|
$50.16
|
$89.40
|
|
31/64"
|
$12.30
|
$22.50
|
$40.20
|
$51.60
|
$90.48
|
|
1/2"
|
$12.00
|
$24.00
|
$40.20
|
$51.60
|
$91.68
|
Numbered Jobber Drills
|
|
Size
|
HSS Import
|
HSS USA
|
Cobalt Import
|
Cobalt USA
|
Precision Twist Drill-M42
|
|
1
|
$8.88
|
$13.80
|
$23.76
|
$30.48
|
$54.12
|
|
2
|
$8.88
|
$13.80
|
$23.76
|
$30.48
|
$54.12
|
|
3
|
$8.04
|
$13.20
|
$22.20
|
$28.68
|
$51.36
|
|
4
|
$8.04
|
$13.20
|
$22.20
|
$28.68
|
$51.36
|
|
5
|
$8.04
|
$12.60
|
$22.20
|
$28.68
|
$51.36
|
|
6
|
$8.04
|
$12.60
|
$22.20
|
$28.68
|
$51.36
|
|
7
|
$7.08
|
$12.00
|
$17.28
|
$22.32
|
$39.48
|
|
8
|
$7.08
|
$12.00
|
$17.28
|
$22.32
|
$40.32
|
|
9
|
$7.08
|
$12.00
|
$17.28
|
$22.32
|
$40.32
|
|
10
|
$7.08
|
$10.80
|
$17.28
|
$22.32
|
$40.32
|
|
11
|
$6.48
|
$10.80
|
$17.28
|
$22.32
|
$40.32
|
|
12 |
$6.48
|
$10.80
|
$17.28
|
$22.32
|
$40.32
|
|
13
|
$6.24
|
$10.80
|
$16.56
|
$21.24
|
$38.76
|
|
14
|
$6.24
|
$10.80
|
$16.56
|
$21.24
|
$38.76
|
|
15
|
$6.24
|
$10.80
|
$16.56
|
$21.24
|
$38.76
|
|
16
|
$6.24
|
$10.80
|
$15.48
|
$19.80
|
$36.36
|
|
17
|
$6.24
|
$10.20
|
$15.12
|
$19.20
|
$35.40
|
|
18
|
$5.28
|
$10.20
|
$13.80
|
$17.28
|
$32.40
|
|
19
|
$5.28
|
$10.20
|
$13.44
|
$17.28
|
$31.44
|
|
20 |
$5.28
|
$9.00
|
$13.44
|
$17.28
|
$30.84
|
|
21
|
$5.04
|
$9.00
|
$13.32
|
$17.28
|
$30.84
|
|
22 |
$5.04
|
$9.00
|
$13.32
|
$17.28
|
$31.44
|
|
23
|
$4.80
|
$9.00
|
$13.32
|
$17.28
|
$31.44
|
|
24 |
$4.80
|
$9.00
|
$13.32
|
$17.28
|
$31.44
|
|
25
|
$4.68
|
$7.80
|
$12.24
|
$15.60
|
$28.32
|
|
26 |
$4.68
|
$7.80
|
$12.12
|
$15.48
|
$28.08
|
|
27
|
$4.68
|
$7.80
|
$12.12
|
$15.48
|
$28.08
|
|
28 |
$4.20
|
$7.20
|
$11.28
|
$14.40
|
$26.28
|
|
29
|
$4.20
|
$7.20
|
$11.04
|
$14.04
|
$25.08
|
|
30 |
$4.20
|
$7.20
|
$10.32
|
$13.20
|
$23.52
|
|
31
|
$4.20
|
$7.20
|
$10.20
|
$13.08
|
$24.00
|
|
32 |
$4.20
|
$7.20
|
$9.96
|
$12.84
|
$23.52
|
|
33
|
$4.20
|
$7.20
|
$9.60
|
$12.48
|
$22.92
|
|
34 |
$4.20
|
$7.20
|
$9.60
|
$12.48
|
$22.92
|
|
35
|
$4.20
|
$7.20
|
$9.60
|
$12.48
|
$22.92
|
|
36 |
$4.20
|
$7.20
|
$9.48
|
$12.00
|
$22.92
|
|
37
|
$4.20
|
$7.20
|
$9.48
|
$12.00
|
$22.92
|
|
38 |
$4.20
|
$7.20
|
$8.76
|
$11.28
|
$20.76
|
|
39
|
$4.20
|
$7.20
|
$8.76
|
$11.28
|
$20.76
|
|
40 |
$4.20
|
$7.20
|
$8.76
|
$11.28
|
$20.40
|
|
41
|
$4.80
|
$7.20
|
$8.64
|
$11.04
|
$20.76
|
|
42 |
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
43
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$19.92
|
|
44
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
45
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
46 |
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
47
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
48 |
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
49
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
50 |
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
51
|
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
52 |
$4.80
|
$7.20
|
$8.52
|
$10.80
|
$20.28
|
|
53
|
$4.80
|
$7.20
|
$9.60
|
$11.88
|
$22.56
|
|
54 |
$4.80
|
$7.80
|
$9.60
|
$11.88
|
$22.56
|
|
55
|
$4.80
|
$7.80
|
$9.60
|
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