Date Updated:May. 14. 2026

Hexalobular Internal Driving Feature for Bolts and Screws

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Hexalobular Internal Driving Feature for Bolts and Screws

Shape and dimensions of hexalobular socket for bolt and screw

Note（1）The allowable depth f of broad mouth part is according to the table.

Unit : mm

Hexalobular socket No. 3 4 5 6 8 10 15 20 25 27 30 40 45 50 55
Nominal dimension(2) A 1.2 1.35 1.5 1.75 2.4 2.8 3.35 3.95 4.5 5.1 5.6 6.75 7.93 8.95 11.35
B 0.85 1.0 1.1 1.27 1.75 2.05 2.4 2.85 3.25 3.68 4.05 4.85 5.64 6.45 8.05
Allowable depth f of the mouth broad part 0.114 0.13 0.22 0.35 0.48 0.56 0.67 0.79 0.90 1.02 1.12 1.18 1.39 1.56 1.98
Allowable limit dimensions of
go-side gauge		 A Max/Min 1.145
1.131
 1.305
1.291
 1.430
1.415		 1.709
1.695		 2.349
2.335		 2.776
2.761		 3.309
3.295		 3.893
3.879		 4.465
4.451		 5.024
5.009		 5.557
5.543		 6.687
6.673		 7.856
7.841		 8.872
8.857		 11.259
11.245
B Max/Min
 0.815
0.800		 0.927
0.912		 1.028
1.013
 1.224
1.210		 1.686
1.672		 1.993
1.979		 2.367
2.353		 2.778
2.764		 3.185
3.170		 3.578
3.564		 3.972
3.958		 4.780
4.766		 5.570
5.555		 6.380
6.366		 7.945
7.930
Gi Max/Min
 0.270
0.263		 0.312
0.305		 0.342
0.318		 0.396
0.371		 0.523
0.498		 0.609
0.585		 0.728
0.704		 0.871
0.846		 0.932
0.907		 1.120
1.095		 1.206
1.182		 1.440
1.415		 1.808
1.784		 1.828
1.804		 2.682
2.657
Ge Max/Min
 0.085
0.078		 0.093
0.087		 0.111
0.107		 0.134
0.130		 0.193
0.188		 0.231
0.227		 0.269
0.265		 0.307
0.303		 0.378
0.371 		0.393
0.387		 0.454
0.448		 0.548
0.544		 0.576
0.572		 0.777
0.773		 0.769
0.765
Allowable limit dimensions of
not-go side gauge
 A Max/Min
 1.222
1.214
 1.382
1.374		 1.506
1.499
 1.785
1.778		 2.425
2.419		 2.852
2.845		 3.385
3.379		 3.970
3.963		 4.566
4.560		 5.126
5.118		 5.659
5.652		 6.814
6.807		 7.983
7.976		 8.999
8.992		 11.415
11.405
B Max
 0.790 0.917 1.044 1.181 1.664 1.956 1.956 2.616 2.868 3.275 3.886 4.661 4.661 6.413 7.684
Gi Max/Min
 0.145
0.137		 0.191
0.180		 0.221
0.208		 0.241
0.231		 0.370
0.360		 0.441
0.431 		0.408
0.398		 0.614
0.602		 0.647
0.637		 0.747
0.735		 0.949
0.939		 1.125
1.112		 1.123
1.110		 1.640
1.628		 2.189
2.176
Ge Max/Min
 0.130
0.119		 0.140
0.132		 0.157
0.147		 0.180
0.173		 0.238
0.231		 0.276
0.269		 0.315
0.307		 0.353
0.345		 0.436
0.429		 0.452
0.445		 0.513
0.505		 0.619
0.612		 0.648
0.640		 0.848
0.840		 0.853
0.845
Allowable limit dimensions of not-go side cylindrical gauge for the dimension B Max/Min 0.965
0.960		 1.105
1.100		 1.205
1.200		 1.445
1.440		 1.925
1.920		 2.285
2.280		 2.765
2.760		 3.285
3.280		 3.725
3.720		 4.265
4.260		 4.665
4.660		 5.605
5.600		 6.665
6.660		 7.385
7.380		 9.665
9.660

Note（2）The curve of hexalobular socket contour is determined by the gauge specified in the above table.

Remarks:

  1. The bore depth c shall be 0.13 mm or smaller for hole No. 15 or smaller and 0.25 mm or smaller for hole over No. 15.
  2. Sink depth t depends on respective product standard.
  3. It is at the discretion of manufacturer as long as the hole bottom shape satisfies the allowable limit of sink depth t.
  4. Hexalobular socket must be able to accept the go-side gauge down to the sink depth t specified by the applicable product standard without effort.
  5. The not-go side gauge must be beyond the allowable depth f of the broad mouth part specified in the table.


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