Threading: Coil Inserts

Coil insert threading is available for UNC, UNF, and metric threads on both milled and turned parts.

Milled Parts and Aluminum or Brass Turned Parts

UNC threads Minimum modeled diameter (in.) Maximum modeled diameter (in.) 75% hole drill size (in.) Maximum thread depth (in.)*
#2-56 0.090 0.096 0.091 0.300
#3-48 0.105 0.110 0.107 0.400
#4-40 0.117 0.125 0.119 0.400
#5-40 0.131 0.137 0.132 0.400
#6-32 0.145 0.153 0.147 0.600
#8-32 0.171 0.178 0.173 0.600
#10-24 0.199 0.208 0.201 0.650
#12-24 0.225 0.234 0.227 0.650
1/4-20 0.261 0.270 0.266 0.650
5/16-18 0.324 0.334 0.332 1.000
3/8-16 0.389 0.399 0.397 1.200
7/16-14 0.453 0.464 0.453 1.200
1/2-13 0.515 0.531 0.531 1.200
*Obstruction by other features of your part, lead-in treatments, or fixturing requirements may reduce the maximum depth of threads.
UNF threads Minimum modeled diameter (in.) Maximum modeled diameter (in.) 75% hole drill size (in.) >Maximum thread depth (in.)*
#2-64 0.090 0.095 0.092 0.300
#3-56 0.103 0.104 0.104 0.300
#4-48 0.117 0.123 0.120 0.400
#6-40 0.144 0.150 0.148 0.600
#8-36 0.170 0.177 0.174 0.600
#10-32 0.197 0.204 0.200 0.650
1/4-28 0.258 0.265 0.261 0.650
5/16-24 0.322 0.329 0.325 1.000
3/8-24 0.384 0.391 0.387 1.000
7/16-20 0.448 0.456 0.452 1.200
1/2-20 0.511 0.519 0.515 1.200
*Obstruction by other features of your part, lead-in treatments, or fixturing requirements may reduce the maximum depth of threads.
Metric threads Minimum modeled diameter (mm) Maximum modeled diameter (mm) 75% hole drill size (mm) Maximum thread depth (mm)*
M2 x 0.4 2.09 2.14 2.14 5.08
M2.5 x 0.45 2.55 2.65 2.60 7.62
M3 x 0.5 3.11 3.25 3.18 10.16
M3.5 x 0.6 3.68 3.79 3.70 15.24
M4 x 0.7 4.15 4.33 4.24 15.24
M5 x 0.8 5.17 5.37 5.27 16.51
M6 x 1.0 6.22 6.41 6.31 16.51
M8 x 1.25 8.27 8.48 8.38 25.40
M10 x 1.5 10.33 10.56 10.56 30.48
M12 x 1.75 12.38 12.64 12.51 30.48
*Obstruction by other features of your part, lead-in treatments, or fixturing requirements may reduce the maximum depth of threads.

Turned Steel, Stainless Steel, Titanium, and Copper Parts

UNC threads Minimum modeled diameter (in.) Maximum modeled diameter (in.) 75% hole drill size (in.) Maximum thread depth (in.)
#2-56 0.090 0.096 0.094 0.300
#3-48 0.105 0.110 0.106 0.400
#4-40 0.117 0.125 0.120 0.400
#5-40 0.131 0.137 0.134 0.400
#6-32 0.145 0.153 0.147 0.400
#8-32 0.171 0.178 0.173 0.400
#10-24* 0.199 0.208 0.203 0.500
#12-24* 0.225 0.234 0.228 0.500
1/4-20* 0.261 0.270 0.266 0.500
*Threads must be centered on the axis of rotation
UNF threads Minimum modeled diameter (in.) Maximum modeled diameter (in.) 75% hole drill size (in.) Maximum thread depth (in.)
#2-64 0.090 0.095 0.093 0.300
#3-56 0.103 0.109 0.106 0.300
#4-48 0.117 0.123 0.120 0.400
#6-40 0.144 0.150 0.147 0.400
#8-36 0.170 0.177 0.173 0.400
#10-32 0.197 0.204 0.201 0.400
1/4-28* 0.258 0.265 0.261 0.500
5/16-24* 0.322 0.329 0.325 0.500
3/8-24* 0.384 0.391 0.387 0.500
7/16-20* 0.448 0.456 0.452 0.500
1/2-20* 0.511 0.519 0.515 0.500
*Threads must be centered on the axis of rotation
Metric threads Minimum modeled diameter (mm) Maximum modeled diameter (mm) 75% hole drill size (mm) Maximum thread depth (mm)
M2.5 x 0.45 2.60 2.70 2.65 7.62
M3 x 0.5 3.11 3.25 3.18 10.16
M3.5 x 0.6 3.68 3.79 3.70 10.16
M4 x 0.7 4.15 4.33 4.20 10.16
M5 x 0.8 5.17 5.37 5.27 10.16
M6 x 1.0* 6.22 6.41 6.31 12.70
M8 x 1.25* 8.27 8.48 8.38 12.70
*Threads must be centered on the axis of rotation