Thread Depth for NATIONAL FORM Tool
Threads Per Inch Pitch Depth Compound Feed
(at 29° angle)
4 .250 .1624 .186
4.5 .2222 .1443 .165
5 .200 .1299 .148
5.5 .1818 .1181 .135
6 .1667 .1083 .124
7 .1429 .0928 .106
8 .1250 .0812 .093
9 .1111 .0722 .083
10 .100 .065 .074
11 .0909 .059 .067
12 .0833 .0541 .062
13 .0769 .050 .057
14 .0714 .0464 .053
16 .0625 .0406 .046
18 .0556 .0361 .041
20 .050 .0325 .037
22 .0454 .0295 .034
24 .0417 .0271 .031
27 .037 .0241 .028
28 .0357 .0232 .027
30 .0333 .0217 .025
32 .0313 .0203 .023
36 .0278 .018 .021
40 .025 .0162 .019
44 .0227 .0148 .017
48 .0208 .0135 .015
50 .020 .013 .015
56 .0179 .0116 .013
64 .0156 .0101 .012
72 .0139 .009 .010
80 .0125 .0081 .009
96 .0104 .0068 .008
Thread Depth for VEE FORM Tool
Threads Per Inch Pitch Depth Compound Feed
(at 29° angle)
4 .250 .1894 .216
4.5 .2222 .1684 .193
5 .200 .1516 .173
5.5 .1818 .1378 .157
6 .1667 .1263 .144
7 .1429 .1082 .123
8 .1250 .0947 .108
9 .1111 .0842 .095
10 .100 .0758 .087
11 .0909 .0689 .078
12 .0833 .0631 .072
13 .0769 .0583 .067
14 .0714 .0541 .062
16 .0625 .0473 .054
18 .0556 .0421 .047
20 .050 .0379 .043
22 .0454 .0345 .038
24 .0417 .0316 .036
27 .037 .0281 .032
28 .0357 .0270 .031
30 .0333 .0253 .029
32 .0313 .0237 .027
36 .0278 .0211 .024
40 .025 .0189 .021
44 .0227 .0172 .020
48 .0208 .0157 .018
50 .020 .0151 .017
56 .0179 .0135 .016
64 .0156 .0118 .014
72 .0139 .0105 .012
80 .0125 .00945 .011
96 .0104 .00901 .010

Source: Atlas / Craftsman Lathe Book

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