Threading: Coil Inserts

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

Milled Parts and Turned Parts (Aluminum and Brass)

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.
threaded holes technical illustration for cnc turning mold

Turned Parts (Hard Metals)

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