[email protected]
Call for help800-871-5022

U.S. Screw Machine Length Twist Drill Size Chart

Screw Machine Length “Drill Bit” Information

Please CONTACT US to discuss your application and receive prompt product cost, literature and technical help.

Size Diameter Flute Length
inch		 Overall Length
inch
U.S. Metric inch MM
1.00 0.0394 1.00 1/2 1 3/8
60 0.0400 1.016 1/2 1 3/8
59 0.0410 1.041 1/2 1 3/8
1.05 0.0413 1.050 1/2 1 3/8
58 0.0420 1.067 1/2 1 3/8
57 0.0430 1.092 1/2 1 3/8
1.10 0.0433 1.100 1/2 1 3/8
1.15 0.0453 1.150 1/2 1 3/8
56 0.0465 1.181 1/2 1 3/8
3/64 0.0469 1.191 1/2 1 3/8
1.20 0.0472 1.200 5/8 1 5/8
1.25 0.0492 1.250 5/8 1 5/8
1.30 0.0512 1.300 5/8 1 5/8
55 0.0520 1.321 5/8 1 5/8
1.35 0.0531 1.350 5/8 1 5/8
54 0.0550 1.397 5/8 1 5/8
1.40 0.0551 1.400 5/8 1 5/8
1.45 0.0571 1.450 5/8 1 5/8
1.50 0.0591 1.500 5/8 1 5/8
53 0.0595 1.511 5/8 1 5/8
1.55 0.0610 1.550 5/8 1 5/8
1/16 0.0625 1.588 5/8 1 5/8
1.60 0.0630 1.600 11/16 1 11/16
52 0.0635 1.613 11/16 1 11/16
1.65 0.0650 1.650 11/16 1 11/16
1.70 0.0669 1.700 11/16 1 11/16
51 0.0670 1.702 11/16 1 11/16
1.75 0.0689 1.750 11/16 1 11/16
50 0.0700 1.778 11/16 1 11/16
1.80 0.0709 1.800 11/16 1 11/16
1.85 0.0728 1.850 11/16 1 11/16
49 0.0730 1.854 11/16 1 11/16
1.90 0.0748 1.900 11/16 1 11/16
48 0.0760 1.930 11/16 1 11/16
1.95 0.0768 1.950 11/16 1 11/16
5/64 0.0781 1.984 11/16 1 11/16
47 0.0785 1.994 11/16 1 11/16
2.00 0.0787 2.000 11/16 1 11/16
2.05 0.0807 2.050 3/4 1 3/4
46 0.0810 2.057 3/4 1 3/4
45 0.0820 2.083 3/4 1 3/4
2.10 0.0827 2.100 3/4 1 3/4
2.15 0.0846 2.150 3/4 1 3/4
44 0.0860 2.184 3/4 1 3/4
2.20 0.0866 2.200 3/4 1 3/4
2.25 0.0886 2.250 3/4 1 3/4
43 0.0890 2.261 3/4 1 3/4
2.30 0.0906 2.300 3/4 1 3/4
2.35 0.0925 2.350 3/4 1 3/4
42 0.0935 2.375 3/4 1 3/4
3/32 0.0938 2.383 3/4 1 3/4
2.40 0.0945 2 1/2 13/16 1 13/16
41 0.0960 2.438 13/16 1 13/16
2.45 0.0965 2.450 13/16 1 13/16
40 0.0980 2.489 13/16 1 13/16
2.50 0.0984 2.500 13/16 1 13/16
39 0.0995 2.527 13/16 1 13/16
38 0.1015 2.578 13/16 1 13/16
2.60 0.1024 2.600 13/16 1 13/16
37 0.1040 2.642 13/16 1 13/16
2.70 0.1063 2.700 13/16 1 13/16
36 0.1065 2.705 13/16 1 13/16
7/64 0.1094 2.779 13/16 1 13/16
35 0.1100 2.794 7/8 1 7/8
2.80 0.1102 2.800 7/8 1 7/8
34 0.1110 2.819 7/8 1 7/8
33 0.1130 2.870 7/8 1 7/8
2.90 0.1142 2.900 7/8 1 7/8
32 0.1160 2.946 7/8 1 7/8
3.00 0.1181 3.000 7/8 1 7/8
31 0.1200 3.048 7/8 1 7/8
3.10 0.1220 3.100 7/8 1 7/8
1/8 0.1250 3.0175 7/8 1 7/8
3.20 0.1260 3.200 15/16 1 15/16
30 0.1285 3.264 15/16 1 15/16
3.30 0.1299 3.300 15/16 1 15/16
3.40 0.1339 3.400 15/16 5 3/81 15/16
29 0.1360 3.454 15/16 1 15/16
3.50 0.1378 3.500 15/16 1 15/16
28 0.1405 3.569 15/16 1 15/16
9/64 0.1406 3.571 15/16 1 15/16
3.60 0.1417 3.600 1 2 1/16
27 0.1440 3.658 1 2 1/16
3.70 0.1457 3.700 1 2 1/16
26 0.1470 3.734 1 2 1/16
25 0.1495 3.797 1 2 1/16
3.80 0.1496 3.800 1 2 1/16
24 0.1520 3.861 1 2 1/16
3.90 0.1535 3.900 1 2 1/16
23 0.1540 3.912 1 2 1/16
5/32 0.1562 3.967 1 2 1/16
22 0.1570 3.988 1 1/16 2 1/8
4.00 0.1575 4.000 1 1/16 2 1/8
21 0.1590 4.039 1 1/16 2 1/8
20 0.1610 4.089 1 1/16 2 1/8
4.10 0.1614 4.100 1 1/16 2 1/8
4.20 0.1654 4.200 1 1/16 2 1/8
19 0.1660 4.216 1 1/16 2 1/8
4.30 0.1693 4.300 1 1/16 2 1/8
18 0.1695 4.305 1 1/16 2 1/8
11/64 0.1719 4.366 1 1/16 2 1/8
17 0.1730 4.394 1 1/8 2 3/16
4.40 0.1732 4.400 1 1/8 2 3/16
16 0.1770 4.496 1 1/8 2 3/16
4.50 0.1772 4.500 1 1/8 2 3/16
15 0.1800 4.572 1 1/8 2 3/16
4.60 0.1811 4.600 1 1/8 2 3/16
14 0.1820 4.623 1 1/8 2 3/16
13 4.70 0.1850 4.700 1 1/8 2 3/16
3/16 0.1875 4.762 1 1/8 2 3/16
12 4.80 0.1890 4.800 1 3/16 2 1/4
11 0.1910 4.851 1 3/16 2 1/4
4.90 0.1929 4.900 1 3/16 2 1/4
10 0.1935 4.915 1 3/16 2 1/4
9 0.1960 4.978 1 3/16 2 1/4
5.00 0.1969 5.000 1 3/16 2 1/4
8 0.1990 5.054 1 3/16 2 1/4
5.10 0.2008 5.100 1 3/16 2 1/4
7 0.2010 5.105 1 3/16 2 1/4
13/64 0.2031 5.159 1 3/16 2 1/4
6 0.2040 5.182 1 1/4 2 3/8
5.20 0.2047 5.200 1 1/4 2 3/8
5 0.2055 5.220 1 1/4 2 3/8
5.30 0.2087 5.300 1 1/4 2 3/8
4 0.2090 5.309 1 1/4 2 3/8
5.40 0.2126 5.400 1 1/4 2 3/8
3 0.2130 5.410 1 1/4 2 3/8
5.50 0.2165 5.500 1 1/4 2 3/8
7/32 0.2188 5.558 1 1/4 2 3/8
5.60 0.2205 5.600 1 5/16 2 7/16
2 0.2210 5.613 1 5/16 2 7/16
5.70 0.2244 5.700 1 5/16 2 7/16
1 0.2280 5.791 1 5/16 2 7/16
5.80 0.2283 5.800 1 5/16 2 7/16
5.90 0.2323 5.600 1 5/16 2 7/16
A 0.2340 5.944 1 5/16 2 7/16
15/64 0.2344 5.954 1 5/16 2 7/16
6.00 0.2362 6.000 1 3/8 2 1/2
B 0.2380 6.045 1 3/8 2 1/2
6.10 0.2402 6.100 1 3/8 2 1/2
C 0.2420 6.147 1 3/8 2 1/2
6.20 0.2441 6.200 1 3/8 2 1/2
D 0.2460 6.248 1 3/8 2 1/2
6.30 0.2480 6.300 1 3/8 2 1/2
E, 1/4 0.2500 6.350 1 3/8 2 1/2
6.40 0.2520 6.400 1 7/16 2 5/8
6.50 0.2559 6.500 1 7/16 2 5/8
F 0.2570 6.528 1 7/16 2 5/8
6.60 0.2598 6.600 1 7/16 2 5/8
G 0.2610 6.629 1 7/16 2 5/8
6.70 0.2638 6.700 1 7/16 2 5/8
17/64 0.2656 6.746 1 7/16 2 5/8
H 0.2660 6.756 1 1/2 2 11/16
6.80 0.2677 6.800 1 1/2 2 11/16
6.90 0.2717 6.900 1 1/2 2 11/16
I 0.2720 6.909 1 1/2 2 11/16
7.00 0.2756 7.000 1 1/2 2 11/16
J 0.2770 7.036 1 1/2 2 11/16
7.10 0.2795 7.100 1 1/2 2 11/16
K 0.2810 7.137 1 1/2 2 11/16
9/32 0.2812 7.142 1 1/2 2 11/16
7.20 0.2835 7.200 1 9/16 2 3/4
7.30 0.2874 7.300 1 9/16 2 3/4
L 0.2900 7.366 1 9/16 2 3/4
7.40 0.2913 7.400 1 9/16 2 3/4
M 0.2950 7.493 1 9/16 2 3/4
7.50 0.2953 7.500 1 9/16 2 3/4
19/64 0.2969 7.541 1 9/16 2 3/4
7.60 0.2992 7.600 1 5/8 2 13/16
N 0.3020 7.671 1 5/8 2 13/16
7.70 0.3031 7.700 1 5/8 2 13/16
7.80 0.3071 7.800 1 5/8 2 13/16
7.90 0.3110 7.900 1 5/8 2 13/16
5/16 0.3125 7.938 1 5/8 2 13/16
8.00 0.3150 8.000 1 11/16>/td> 2 15/16
O 0.3160 8.026 1 11/16 2 15/16
8.10 0.3189 8.100 1 11/16 2 15/16
8.20 0.3228 8.200 1 11/16 2 15/16
P 0.3230 8.204 1 11/16 2 15/16
8.30 0.3268 8.300 1 11/16 2 15/16
21/64 0.3281 8.334 1 11/16 2 15/16
8.40 0.3307 8.400 1 11/16 3
Q 0.3320 8.433 1 11/16 3
8.50 0.3346 8.500 1 11/16 3
8.60 0.3386 8.600 1 11/16 3
R 0.3390 8.611 1 11/16 3
8.70 0.3425 8.700 1 11/16 3
11/32 0.3438 8.733 1 11/16 3
8.80 0.3465 8.800 1 3/4 3 1/16
S 0.3480 8.839 1 3/4 3 1/16
8.90 0.3504 8.900 1 3/4 3 1/16
9.00 0.3543 9.000 1 3/4 1/16
T 0.3580 9.093 1 3/4 3 1/16
9.10 0.3583 9.100 1 3/4 3 1/16
23/64 0.3594 9.129 1 3/4 3 1/16
9.20 0.3622 9.200 1 13/16 3 1/8
9.30 0.3661 9.300 1 13/16 3 1/8
U 0.3680 9.347 1 13/16 3 1/8
9.40 0.3701 9.400 1 13/16 3 1/8
9.50 0.3740 9.500 1 13/16 3 1/8
3/8 0.3750 9.525 1 13/16 3 1/8
V 0.3770 9.576 1 7/8 3 1/4
9.60 0.3780 9.600 1 7/8 3 1/4
9.70 0.3819 9.700 1 7/8 3 1/4
9.80 0.3858 9.800 1 7/8 3 1/4
W 0.3860 9.804 1 7/8 3 1/4
9.90 0.3898 9.900 1 7/8 3 1/4
25/64 0.3906 9.921 1 7/8 3 1/4
10.00 0.3937 10.00 1 15/16 3 5/16
X 0.3970 10.084 1 15/16 3 5/16
10.20 0.4016 10.200 1 15/16 3 5/16
Y 0.4040 10.262 1 15/16 3 5/16
13/32 0.4062 10.317 1 15/16 3 5/16
Z 0.4130 10.490 2 3 3/8
10.50 0.4134 10.500 2 3 3/8
27/64 0.4219 10.716 2 3 3/8
10.80 0.4252 10.800 2 1/16 3 7/16
11.00 0.4331 11.000 2 1/16 3 7/16
7/16 0.4375 11.112 2 1/16 3 7/16
11.20 0.4409 11.200 2 1/8 3 9/16
11.50 0.4528 11.500 2 1/8 3 9/16
29/64 0.4531 11.509 2 1/8 3 9/16
11.80 0.4646 11.800 2 1/8 3 5/8
15/32 0.4688 11.908 2 1/8 3 5/8
12.00 0.4724 12.000 2 3/16 3 11/16
12.20 0.4803 12.200 2 3/16 3 11/16
31/64 0.4844 12.304 2 3/16 3 11/16
12.50 0.4921 12.500 2 1/4 3 3/4
1/2 0.500 12.700 2 1/4 3 3/4

WHY DO MY TOOLS WEAR QUICKLY OR BREAK?

Note that excessive tool wear or breakage is often caused by one of the following:

  • Improper surface speeds
  • Improper feed rates
  • Improper cutting tool type or material (HSS vs TiN vs Carbide, etc.)
  • Dull tooling
  • Hard spots in the material such as scale, silica, etc.
  • Improper coolant or lubricant type
  • Inadequate coolant or lubricant (overall for chip removal, rubbing, etc.)
  • Inadequate coolant or lubricant (at the tip of the tooling)
  • The tool is not rigid enough (try drill bushings or guides, guide rods on the drilling machine, etc.)
  • Too deep of a cut without proper chip removal – Chip packing (try peck drilling, air blast or coolant through the tool options, etc.)
  • Tools that were manufactured or sharpened incorrectly. (watch those clearance, rake and lip angles as well as rough surfaces, etc.)

CALCULATING CYCLE TIME WHEN DRILLING:

We can help you lower your cycle time when drilling holes in a part or multiple parts. Generally, this is the calculation we use to figure out the time it will take to perform a process:

DEPTH divided by FEED = ROTATIONS.
ROTATIONS divided by RPM = MINUTES.
MINUTES multiplied by 60 = SECONDS it takes for the process.

(DEPTH = 30% of the diameter of the tool plus the thickness of the material)
Add in stroke up to product time
Add in stroke back to home time
Add in clamp and unclamp time
Add in any human factors, etc.
Add in time for potentially dull tooling, etc.
Add in time for less than adequate machine thrust, etc.

We use the following charts to estimate these numbers:

Recommended Tool Speed Chart

Please CONTACT US to discuss your application and receive prompt product cost, literature and technical help.

Thank you for giving us the opportunity to serve you!

contact us