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Internal and External Tooth Lock Washer
These washers prevent nuts or bolts from backing with sharp flanges, or teeth, that are shaped to cut into the material.
Other Names: Star Washer
Internal - Teeth point inward, toward the threads of the fastener.
External - Teeth point outward, away from the threads of the fastener.
Internal/External - Has teeth going in both directions for superior hold.
Internal Washer Dimensions
ASME B18.21.1
| Nominal Dia. | Actual ID | OD | Thickness |
|---|---|---|---|
| No. 2 | 0.089 - 0.095 | 0.175 - 0.200 | 0.010 - 0.016 |
| No. 3 | 0.102 - 0.109 | 0.215 - 0.232 | 0.010 - 0.016 |
| No. 4 | 0.115 - 0.123 | 0.245 - 0.270 | 0.012 - 0.018 |
| No. 5 | 0.129 - 0.136 | 0.255 - 0.280 | 0.014 - 0.020 |
| No. 6 | 0.141 - 0.150 | 0.275 - 0.295 | 0.016 - 0.022 |
| No. 8 | 0.168 - 0.176 | 0.325 - 0.340 | 0.018 - 0.023 |
| No. 10 | 0.195 - 0.204 | 0.365 - 0.381 | 0.018 - 0.024 |
| No. 12 | 0.221 - 0.231 | 0.394 - 0.410 | 0.020 - 0.027 |
| 1/4 | 0.256 - 0.267 | 0.460 - 0.478 | 0.023 - 0.028 |
| 5/16 | 0.320 - 0.332 | 0.594 - 0.610 | 0.028 - 0.034 |
| 3/8 | 0.384 - 0.398 | 0.670 - 0.692 | 0.032 - 0.040 |
| 7/16 | 0.448 - 0.464 | 0.740 - 0.789 | 0.032 - 0.040 |
| 1/2 | 0.512 - 0.530 | 0.867 - 0.900 | 0.037 - 0.045 |
| 9/16 | 0.576 - 0.596 | 0.957 - 0.985 | 0.037 - 0.045 |
| 5/8 | 0.640 - 0.663 | 1.045 - 1.071 | 0.042 - 0.050 |
| 3/4 | 0.769 - 0.795 | 1.220 - 1.245 | 0.047 - 0.055 |
| 7/8 | 0.894 - 0.927 | 1.364 - 1.410 | 0.052 - 0.060 |
| 1 | 1.019 - 1.060 | 1.590 - 1.637 | 0.059 - 0.067 |
| 1 1/8 | 1.144 - 1.192 | 1.799 - 1.830 | 0.059 - 0.067 |
| 1 1/4 | 1.275 - 1.325 | 1.921 - 1.975 | 0.059 - 0.067 |
External Washer Dimensions
ASME B18.21.1
| Nominal Dia. | Actual ID | OD | Thickness |
|---|---|---|---|
| No. 2 | 0.086 - 0.095 | 0.177 - 0.189 | 0.010 - 0.013 |
| No. 3 | 0.102 - 0.109 | 0.220 - 0.235 | 0.010 - 0.016 |
| No. 4 | 0.115 - 0.123 | 0.245 - 0.260 | 0.012 - 0.018 |
| No. 5 | 0.129 - 0.136 | 0.270 - 0.285 | 0.014 - 0.020 |
| No. 6 | 0.141 - 0.150 | 0.305 - 0.320 | 0.016 - 0.022 |
| No. 8 | 0.168 - 0.176 | 0.365 - 0.381 | 0.018 - 0.023 |
| No. 10 | 0.195 - 0.204 | 0.395 - 0.410 | 0.018 - 0.024 |
| No. 12 | 0.221 - 0.231 | 0.460 - 0.475 | 0.020 - 0.027 |
| 1/4 | 0.256 - 0.267 | 0.494 - 0.510 | 0.023 - 0.028 |
| 5/16 | 0.320 - 0.332 | 0.588 - 0.610 | 0.028 - 0.034 |
| 3/8 | 0.384 - 0.398 | 0.670 - 0.694 | 0.032 - 0.040 |
| 7/16 | 0.448 - 0.464 | 0.740 - 0.760 | 0.032 - 0.040 |
| 1/2 | 0.513 - 0.530 | 0.880 - 0.900 | 0.037 - 0.045 |
| 9/16 | 0.576 - 0.596 | 0.960 - 0.985 | 0.037 - 0.045 |
| 5/8 | 0.641 - 0.663 | 1.045 - 1.070 | 0.042 - 0.050 |
| 3/4 | 0.768 - 0.795 | 1.220 - 1.260 | 0.047 - 0.055 |
| 7/8 | 0.897 - 0.927 | 1.380 - 1.410 | 0.052 - 0.060 |
| 1 | 1.025 - 1.060 | 1.590 - 1.620 | 0.059 - 0.067 |
Internal/External Washer Dimensions
ASME B18.21.1
| Nominal Dia. | Actual ID | OD | Thickness |
|---|---|---|---|
| No. 4 | 0.115 - 0.123 | 0.460 - 0.475 | 0.016 - 0.021 |
| No. 6 | 0.141 - 0.150 | 0.495 - 0.510 | 0.023 - 0.028 |
| No. 8 | 0.168 - 0.176 | 0.494 - 0.506 | 0.023 - 0.028 |
| No. 10 | 0.195 - 0.204 | 0.580 - 0.610 | 0.028 - 0.034 |
| 1/4 | 0.256 - 0.267 | 0.725 - 0.760 | 0.032 - 0.040 |
| 5/16 | 0.320 - 0.332 | 0.865 - 0.900 | 0.032 - 0.040 |
| 3/8 | 0.384 - 0.398 | 0.965 - 0.985 | 0.037 - 0.045 |
| 7/16 | 0.448 - 0.464 | 1.045 - 1.070 | 0.042 - 0.050 |
| 1/2 | 0.512 - 0.530 | 1.220 - 1.260 | 0.047 - 0.055 |
| 5/8 | 0.640 - 0.663 | 1.380 - 1.410 | 0.052 - 0.060 |