Table 5. Unified Miniature Screw Threads—Limits of Size and Tolerances
External Threads Pitch Diam.
Internal Threads Pitch Diam.
Lead Angle at Basic Pitch Diam.
Sectional Area at Minor Diam. at D—1.28 p
Major Diam.
Minor Diam.
Minor Diam.
Major Diam.
Max b
Max b
Max c
Min d
Min b
Min b
Min e
Max d
Pitch
Min
Min
Max
Max
Size Designation a
mm mm mm mm mm mm mm mm mm mm mm mm mm deg min sq mm
0.30 UNM 0.080 0.35 UNM 0.090 0.40 UNM 0.100 0.45 UNM 0.100 0.50 UNM 0.125 0.55 UNM 0.125 0.60 UNM 0.150 0.70 UNM 0.175 0.80 UNM 0.200 0.90 UNM 0.225 1.00 UNM 0.250 1.10 UNM 0.250 1.20 UNM 0.250 1.40 UNM 0.300 0.30 UNM 318 0.35 UNM 282 0.40 UNM 254 0.45 UNM 254 0.50 UNM 203 0.55 UNM 203 0.60 UNM 169 0.70 UNM 145 0.80 UNM 127 0.90 UNM 113 1.00 UNM 102 1.10 UNM 102 1.20 UNM 102 1.40 UNM 85
0.300 0.284 0.350 0.333 0.400 0.382 0.450 0.432 0.500 0.479 0.550 0.529 0.600 0.576 0.700 0.673 0.800 0.770 0.900 0.867 1.000 0.964 1.100 1.064 1.400 1.358 1.200 1.164
0.248 0.292 0.335 0.385 0.419 0.469 0.503 0.586 0.670 0.754 0.838 0.938 1.038 1.205
0.234 0.277 0.319 0.369 0.401 0.451 0.483 0.564 0.646 0.728 0.810 0.910 1.010 1.173
0.204 0.242 0.280 0.330 0.350 0.400 0.420 0.490 0.560 0.630 0.700 0.800 0.900 1.040
0.183 0.220 0.256 0.306 0.322 0.372 0.388 0.454 0.520 0.586 0.652 0.752 0.852 0.984
0.217 0.256 0.296 0.346 0.370 0.420 0.444 0.518 0.592 0.666 0.740 0.840 0.940 1.088
0.254 0.297 0.340 0.390 0.422 0.472 0.504 0.586 0.668 0.750 0.832 0.932 1.032 1.196
0.248 0.292 0.335 0.385 0.419 0.469 0.503 0.586 0.670 0.754 0.838 0.938 1.038 1.205
0.262 0.307 0.351 0.401 0.437 0.487 0.523 0.608 0.694 0.780 0.866 0.966 1.066 1.237
0.306 0.356 0.407 0.457 0.509 0.559 0.611 0.713 0.814 0.916 1.018 1.118 1.218 1.422
0.327 0.380 0.432 0.482 0.538 0.588 0.644 0.750 0.856 0.962 1.068 1.168 1.268 1.480
5 52 0.0307 5 37 0.0433 4 44 0.0814 0.0581 0.0908 4 51 0.1195 5 26 0.1780 26 26 26 26 0.232 0.363 5 26 0.294 4 51 0.478 5 5 5 5 5 0.1307 26
4 23
0.608
4 32 0.811
Thds. per in.
inch
inch
inch
inch
inch
inch
inch
inch
inch
inch
inch
inch deg min
sq in
0.0118 0.0112 0.0098 0.0092 0.0080 0.0072 0.0085 0.0100 0.0098 0.0104 0.0120 0.0129 5 52 0.0000475 0.0138 0.0131 0.0115 0.0109 0.0095 0.0086 0.0101 0.0117 0.0115 0.0121 0.0140 0.0149 5 37 0.0000671 0.0177 0.0170 0.0152 0.0145 0.0130 0.0120 0.0136 0.0154 0.0152 0.0158 0.0180 0.0190 4 44 0.0001262 0.0157 0.0150 0.0132 0.0126 0.0110 0.0101 0.0117 0.0134 0.0132 0.0138 0.0160 0.0170 5 26 0.0197 0.0189 0.0165 0.0158 0.0138 0.0127 0.0146 0.0166 0.0165 0.0172 0.0200 0.0212 5 26 0.0000901 0.0001407 0.0217 0.0208 0.0185 0.0177 0.0157 0.0146 0.0165 0.0186 0.0185 0.0192 0.0220 0.0231 4 51 0.0001852 0.0236 0.0227 0.0198 0.0190 0.0165 0.0153 0.0175 0.0198 0.0198 0.0206 0.0240 0.0254 5 26 0.000203 0.0276 0.0265 0.0231 0.0222 0.0193 0.0179 0.0204 0.0231 0.0231 0.0240 0.0281 0.0295 5 26 0.000276 0.0315 0.0303 0.0264 0.0254 0.0220 0.0205 0.0233 0.0263 0.0264 0.0273 0.0321 0.0337 5 26 0.000360 0.0354 0.0341 0.0297 0.0287 0.0248 0.0231 0.0262 0.0295 0.0297 0.0307 0.0361 0.0379 5 26 0.000456 0.0394 0.0380 0.0330 0.0319 0.0276 0.0257 0.0291 0.0327 0.0330 0.0341 0.0401 0.0420 5 26 0.000563 0.0433 0.0419 0.0369 0.0358 0.0315 0.0296 0.0331 0.0367 0.0369 0.0380 0.0440 0.0460 4 51 0.000741 0.0472 0.0458 0.0409 0.0397 0.0354 0.0335 0.0370 0.0406 0.0409 0.0420 0.0480 0.0499 0.0551 0.0535 0.0474 0.0462 0.0409 0.0387 0.0428 0.0471 0.0474 0.0487 0.0560 0.0583 4 32 0.001257 4 23 0.000943
a Sizes shown in bold type are preferred. b This is also the basic dimension. c This limit, in conjunction with root form shown in Table 2 , is advocated for use when optical projection methods of gaging are employed. For mechanical gaging the minimum minor diameter of the internal thread is applied. d This limit is provided for reference only. In practice, the form of the threading tool is relied upon for this limit. e This limit is provided for reference only, and is not gaged. For gaging, the maximum major diameter of the external thread is applied.
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