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GRAD Engineering LLC

 Drill Threads

Number Size Drills
Diameter in Inches

No. Dia.
1 .2280
2 .2210
3 .2130
4 .2090
5 .2055
6 .2040
7 .2010
8 .1990
9 .1960
10 .1935
11 .1910
12 .1890
13 .1850
14 .1820
15 .1800
16 .1770
17 .1730
18 .1695
19 .1660
20 .1610
No. Dia.
21 .1590
22 .1570
23 .1540
24 .1520
25 .1495
26 .1470
27 .1440
28 .1405
29 .1360
30 .1285
31 .1200
32 .1160
33 .1130
34 .1110
35 .1100
36 .1065
37 .1040
38 .1015
39 .0995
40 .0980
No. Dia.
41 .0960
42 .0935
43 .0890
44 .0860
45 .0820
46 .0810
47 .0785
48 .0760
49 .0730
50 .0700
51 .0670
52 .0635
53 .0595
54 .0550
55 .0520
56 .0465
57 .0430
58 .0420
59 .0410
60 .0400
No. Dia.
61 .0390
62 .0380
63 .0370
64 .0360
65 .0350
66 .0330
67 .0320
68 .0310
69 .0292
70 .0280
71 .0260
72 .0250
73 .0240
74 .0225
75 .0210
76 .0200
77 .0180
78 .0160
79 .0145
80 .0135
Letter Size Drills
Diameter in Inches
Ltr. Dia.
A .234
B .238
C .242
D .246
E .250
F .257
G .261
H .266
I .272
J .277
K .281
L .290
M .295
Ltr. Dia.
N .302
O .316
P .323
Q .332
R .339
S .348
T .358
U .368
V .377
W .386
X .397
Y .404
Z .413