Data is for reference only. Test in application for best results

Taptite Thread Forming Fasteners
Suggested Hole Sizes at Percentages of Thread Engagement
Inch Sizes

Nominal
Screw
Size

Pilot Hole Sizes

Percent Thread Engagement

100% 95%

90%*

85%*

80% 75% 70% 65% 60% 55% 50% 45% 40% 35%
2-56 .0744 .0755 .0756 .0761 .0767 .0773 .0779 .0785 .0790 .0796 .0802 .0808 .0814 .0819
3-48 .0855 .0861 .0868 .0875 .0882 .0888 .0895 .0902 .0909 .0916 .0922 .0929 .0936 .0943
4-40 .0958 .0966 .0974 .0982 .0990 .0998 .1006 .1014 .1023 .1031 .1039 .1047 .1055 .1063
5-40 .1088 .1096 .1104 .1112 .1120 .1128 .1136 .1144 .1153 .1161 .1169 .1177 .1185 .1193
6-32 .1177 .1187 .1197 .1207 .1218 .1228 .1238 .1248 .1258 .1268 .1278 .1289 .1299 .1309
8-32 .1437 .1447 .1457 .1467 .1478 .1488 .1498 .1508 .1518 .1528 .1538 .1549 .1559 .1569
10-24 .1629 .1643 .1656 .1670 .1683 .1697 .1710 .1724 .1738 .1751 .1765 .1778 .1792 .1805
10-32 .1697 .1707 .1717 .1727 .1738 .1748 .1758 .1768 .1778 .1788 .1798 .1809 .1819 .1829
12-24 .1889 .1903 .1916 .1930 .1943 .1957 .1970 .1984 .1998 .2011 .2025 .2038 .2052 .2065
1/4-20 .2175 .2191 .2208 .2224 .2240 .2256 .2273 .2289 .2305 .2321 .2338 .2354 .2370 .2386
5/16-18 .2764 .2782 .2800 .2818 .2836 .2854 .2872 .2890 .2908 .2926 .2944 .2963 .2981 .2999
3/8-16 .3344 .3364 .3384 .3405 .3425 .3445 .3466 .3486 .3506 .3527 .3547 .3567 .3588 .3608
7/16-14 .3911 .3934 .3957 .3980 .4004 .4027 .4050 .4073 .4096 .4120 .4143 .4166 .4189 .4213
1/2-13 .4500 .4525 .4550 .4575 .4600 .4625 .4650 .4675 .4700 .4725 .4750 .4775 .4800 .4825
 
Metric Sizes

Nominal
Screw
Size

Pilot Hole Sizes

Percent Thread Engagement

100% 95%

90%*

85%* 80% 75% 70% 65% 60% 55% 50% 45% 40% 35%
M2.5x0.45 2.21 2.22 2.24 2.25 2.27 2.28 2.29 2.31 2.32 2.34 2.35 2.37 2.38 2.40
M3x0.5 2.67 2.69 2.71 2.72 2.74 2.76 2.77 2.79 2.80 2.82 2.84 2.85 2.87 2.90
M3.5x0.6 3.11 3.13 3.15 3.17 3.19 3.21 3.23 3.25 3.27 3.29 3.30 3.32 3.34 3.36
M4x0.7 3.54 3.57 3.59 3.61 3.64 3.66 3.68 3.70 3.73 3.75 3.77 3.79 3.80 3.84
M4.5x0.75 4.01 4.04 4.06 4.09 4.11 4.13 4.16 4.18 4.21 4.23 4.26 4.28 4.30 4.33
M5x0.8 4.48 4.51 4.53 4.56 4.58 4.61 4.64 4.66 4.69 4.71 4.74 4.77 4.79 4.82
M6x1.0 5.35 5.38 5.42 5.45 5.48 5.51 5.54 5.58 5.61 5.64 5.67 5.71 5.74 5.77
M6.3x1.0 5.65 5.68 5.72 5.75 5.78 5.81 5.84 5.88 5.91 5.94 5.97 6.01 6.04 6.07
M7x1.0 6.35 6.38 6.42 6.45 6.48 6.51 6.54 6.58 6.61 6.64 6.67 6.71 6.74 6.77
M8x1.25 7.19 7.23 7.27 7.31 7.35 7.39 7.43 7.47 7.51 7.55 7.59 7.63 7.67 7.72
M10x1.5 9.03 9.07 9.12 9.17 9.22 9.27 9.32 9.37 9.41 9.46 9.51 9.56 9.61 9.66
M12x1.75 10.86 10.92 10.98 11.03 11.09 11.15 11.2 11.26 11.31 11.37 11.43 11.49 11.55 11.60

 

SUGGESTED THREAD ENGAGEMENT GUIDELINES
Powdered Metal or Cast Iron 50 - 65%
Cold Rolled Steel 65 - 70%
Aluminum 70 - 80%
Thin Sheet Metals 80 - 95%

 

PROPER DESIGN
Due to the variability of materials, such as cast iron, magnesium and powdered metals, please contact an MEI  application specialist for proper hole size recommendations to ensure optimum fastener performance.

* - Pilot holes listed under the 90% and 85% thread engagement columns are recommended for single punch extruded holes. For pilot hole tolerance, +5% to -10% of the nominal value is recommended.

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