Threaded Holes Guidelines
Threaded Parts in 5 Easy Steps:
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Understanding thread depth: All of our threads are CNC cut using a thread mill and manually gauged during final inspection. Thread milling is more reliable than manual tapping, but for the best results thread depth is regulated to about 2.5 times the thread diameter (refer to maximum depth in the table below). Don’t worry if your hole is longer or shorter, here’s how our software will design your thread: |
QUICK THREADS: |
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Blind hole <Ø×2.5Threaded to the end (the last thread will stop about 0.25 mm from the end or drill tip) |
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Blind hole >Ø×2.5The first portion of the hole will be threaded (to a depth of about Ø×2.5 ) |
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Through hole <Ø×2.5Completely threaded |
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Through hole >Ø×2.5If we can access both sides, the thread selection will allow selection of either or both sides. If you select both the threads will each be a little less than ½ the depth of the hole: they will not meet in the middle. |
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Through hole >Ø×5For longer holes the threads will be cut to the maximum depth possible |
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Tip for increasing overall thread depthAdding a counter bore will enable the thread tool to reach further. A counter bore, or countersink, is also a great Design for Assembly (DfA) feature. |
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Coil and key inserts
Coil inserts (HELICOIL®) and key inserts can provide a more durable thread in softer materials. We can machine insert ready threads, but do not supply the inserts.
Other considerations:
Occasionally part features or fixturing will obstruct the thread tools, if a hole cannot be threaded we show this by omitting the thread on the interactive quotation.
For threading on turned parts simply model the nominal diameter; there is no need to model the threads.
Our standardised toolset enables incredibly quick CNC manufacturing (as quick as same day) however it also means we can only provide the threads listed, left handed threads, diameters or pitches not listed are not currently possible.
We can only support modelled threads larger than M12 or UNC ½”-13 (½” Unified Course by 13 Thread Per Inch (TPI)) or greater – they will be milled using a ball cutter.
We are unable to support .SLT file formats
Internal Metric
Thread Pitch
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Process | Max Thread depth | CAD Ø * | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Internal metric: standard or coarse - all dimensions in mm |
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M1.6 x 0.35** | Soft** | 3.00 | 1.25 | 1.22 | 1.32 | 1.65 | |
M2 x0.4 |
✓ | 5.08 | 1.60 | 1.57 | 1.68 | 2.05 | |
M2.5 x 0.45 |
✓ | 5.08 | 2.05 | 2.01 | 2.14 | 2.60 | |
M3 x 0.5 |
✓ | ✓ | 7.62 | 2.50 | 2.46 | 2.60 | 3.10 |
M3.5 x 0.6 |
✓ | ✓ | 10.16 | 2.90 | 2.85 | 3.01 | 3.60 |
M4 x 0.7 |
✓ | ✓ | 10.16 | 3.30 | 3.24 | 3.42 | 4.10 |
M5 x 0.8 |
✓ | ✓ | 15.24 / 10.16T* | 4.20 | 4.14 | 4.33 | 5.10 |
M6 x 1.0 |
✓ | ✓ | 16.51 / 12.27T* | 5.00 | 4.92 | 5.15 | 6.10 |
M8 x 1.25 |
✓ | ✓ | 16.51 / 12.27T* | 6.80 | 6.65 | 6.91 | 8.20 |
M10 x 1.5 |
✓ | 25.40 | 8.50 | 8.38 | 8.68 | 10.20 | |
M12 x 1.75 |
✓ | 25.40 | 10.20 | 10.00 | 10.44 | 12.20 | |
Internal metric: fine or special - all dimensions in mm |
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M8 x 1.0 FINE |
Metal*** | ✓ | 16.51 | 7.00 | 6.91 | 7.16 | 8.20 |
M10 x 1.25 FINE |
Metal*** | ✓ | 25.40 | 8.75 | 8.65 | 8.91 | 10.20 |
M12 x 1.25 FINE |
Metal*** | 25.40 | 10.75 | 10.65 | 10.91 | 12.20 |
Obstruction by other features of your part, lead-in treatments, or fixturing requirements may reduce the maximum depth of threads.
* also known as - Pilot Hole Drill Ø
Soft** Only available in soft metals
Metal *** -Only available in metal materials (both hard and soft)
T* - Turned
The Minimum Ø and Maximum Ø are the limits our software uses to recognise holes that can be threaded
The maximum thread depth is the limit of our thread cutting tools, starting from the hole face selected, excluding any chamfers of counter bores. Your hole should be deeper than this depth to allow for swarf. Even if you model a deeper hole, only the first portion will be threaded.
Coil insert metric
Thread Pitch
|
Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Internal metric: standard or coarse - all dimensions in mm |
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M2 x 0.4 | ✓ | 5.08 | 2.14 | 2.09 | 2.14 | 2.05 | |
M2.5 x 0.45 | ✓ | ✓ | 7.62 | 2.6 | 2.55 | 2.65 | 2.60 |
M3 x 0.5 | ✓ | ✓ | 10.16 | 3.18 | 3.11 | 3.25 | 3.10 |
M3.5 x 0.6 | ✓ | ✓ | 15.24 / 10.16T* | 3.7 | 3.68 | 3.79 | 3.60 |
M4 x 0.7 | ✓ | ✓ | 15.24 / 10.16T* | 4.24 | 4.15 | 4.33 | 4.10 |
M5 x 0.8 | ✓ | ✓ | 16.51 / 10.16T* | 5.27 | 5.17 | 5.37 | 5.10 |
M6 x 1.0 | ✓ | ✓ | 16.51 / 12.7T* | 6.31 | 6.22 | 6.41 | 6.10 |
M8 x 1.25 | ✓ | ✓ | 25.4 / 12.7T* | 8.38 | 8.27 | 8.48 | 8.20 |
M10 x 1.5 | ✓ | 30.48 | 10.56 | 10.33 | 10.56 | 10.20 | |
M12 x 1.75 | ✓ | 30.48 | 12.51 | 12.38 | 12.64 | 12.20 |
* also known as Pilot Hole Drill Ø
T* - Turning
Outside diameter metric
Thread Pitch
|
Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Metric outside diameter: standard or coarse - all dimensions in mm |
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M3.5 x 0.6 |
✓ | 7 | 3.5 | 3.35 | 3.53 | 3.16 | |
M4 x 0.7 |
✓ | 8 | 4 | 3.84 | 4.03 | 4.10 | |
M5 x 0.8 |
✓ | 10 | 5 | 4.83 | 5.03 | 5.10 | |
M6 x 1.0 |
✓ | 12 | 6 | 5.79 | 6.02 | 6.10 | |
M8 x 1.25 |
✓ | 16 | 8 | 7.76 | 8.03 | 8.20 | |
M10 x 1.5 |
✓ | 20 | 10 | 9.73 | 10.03 | 10.20 | |
M12 x 1.75 |
M* | ✓ | 24 | 12 | 11.7 | 12.02 | 12.20 |
M14 x 2.0 |
M* | ✓ | 28 | 14 | 13.68 | 14.03 | 14.25 |
M16 x 2.0 |
M* | ✓ | 32 | 16 | 15.68 | 16.02 | 16.25 |
M20 x 2.5 |
M* | ✓ | 40 | 20 | 19.62 | 20.03 | 20.25 |
Metric outside diameter: fine or special - all dimensions in mm |
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M8 x 1.0 FINE |
✓ | 16 | 8 | 7.8 | 8.03 | 8.20 | |
M10 x 0.75 SP |
✓ | 20 | 10 | 9.84 | 10.03 | 10.20 | |
M10 x 1.25 FINE |
✓ | 20 | 10 | 9.76 | 10.03 | 10.20 | |
M12 x 1.25 FINE |
✓ | 24 | 12 | 11.76 | 12.02 | 12.20 | |
M12 x 1.0 SP |
✓ | 24 | 12 | 11.79 | 12.02 | 12.20 | |
M12 x 1.5 SP |
M* | ✓ | 24 | 12 | 11.73 | 12.02 | 12.20 |
M14 x 1.5 FINE |
M* | ✓ | 28 | 14 | 13.73 | 14.03 | 14.25 |
M15 x 1.0 SP |
M* | ✓ | 30 | 15 | 14.79 | 15.03 | 15.25 |
M16 x 1.5 FINE |
M* | ✓ | 32 | 16 | 15.73 | 16.02 | 16.25 |
M17 x 1.0 SP |
M* | ✓ | 34 | 17 | 16.79 | 17.03 | 17.25 |
M18 x 1.5 FINE |
M* | ✓ | 36 | 18 | 17.73 | 18.03 | 18.25 |
M20 x 1.5 FINE |
M* | ✓ | 40 | 20 | 19.73 | 20.03 | 20.25 |
*also known as - Pilot Hole Drill Ø
M* On a 3 or 5-axis mill larger external threads can be cut with a ball nose cutter… refer to Special threads.
Internal Inch
Thread Pitch
|
Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Internal inch: unified fine UNF - all dimensions in inches |
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#2-64 | ✓ | 0.20 | 0.072 | 0.069 | 0.075 | 0.09 | |
#3-56 | ✓ | 0.20 | 0.083 | 0.080 | 0.084 | 0.10 | |
#4-48 | ✓ | ✓ | 0.30 | 0.093 | 0.087 | 0.099 | 0.12 |
#5-44 | ✓ | ✓ | 0.30 | 0.104 | 0.100 | 0.104 | 0.13 |
#6-40 | ✓ | ✓ | 0.40 | 0.115 | 0.111 | 0.119 | 0.14 |
#8-36 | ✓ | ✓ | 0.40 | 0.138 | 0.134 | 0.142 | 0.17 |
#10-32 | ✓ | ✓ | 0.60 | 0.160 | 0.156 | 0.164 | 0.19 |
#12-28 | ✓ | ✓ | 0.6 / 0.5T* | 0.182 | 0.177 | 0.186 | 0.22 |
1/4-28 | ✓ | ✓ | 0.65 | 0.216 | 0.211 | 0.220 | 0.26 |
5/16-24 | ✓ | ✓ | 0.65 /0.5T* | 0.272 | 0.267 | 0.277 | 0.32 |
3/8-24 | ✓ | ✓ | 1 / 0.5T* | 0.335 | 0.330 | 0.340 | 0.38 |
7/16-20 | ✓ | ✓ | 1 / 0.5T* | 0.389 | 0.383 | 0.395 | 0.44 |
1/2-20 | ✓ | ✓ | 1.2 / 0.5T* | 0.452 | 0.446 | 0.457 | 0.51 |
Internal inch: unified coarse CNC - all dimensions in inches |
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#2-56 | ✓ | 0.20 | 0.070 | 0.067 | 0.074 | 0.09 | |
#3-48 | ✓ | 0.20 | 0.082 | 0.076 | 0.084 | 0.10 | |
#4-40 | ✓ | ✓ | 0.30 | 0.089 | 0.085 | 0.094 | 0.12 |
#5-40 | ✓ | ✓ | 0.30 | 0.102 | 0.098 | 0.104 | 0.13 |
#6-32 | ✓ | ✓ | 0.40 | 0.109 | 0.105 | 0.114 | 0.14 |
#8-32 | ✓ | ✓ | 0.40 | 0.135 | 0.130 | 0.139 | 0.17 |
#10-24 | ✓ | 0.60 | 0.151 | 0.145 | 0.156 | 0.19 | |
#12-24 | ✓ | ✓ | 0.6 / 0.5T* | 0.176 | 0.171 | 0.181 | 0.22 |
1/4-20 | ✓ | ✓ | 0.65 / 0.5T* | 0.202 | 0.196 | 0.207 | 0.26 |
5/16-18 | ✓ | 0.65 | 0.259 | 0.252 | 0.265 | 0.32 | |
3/8-16 | ✓ | 1.00 | 0.314 | 0.307 | 0.321 | 0.38 | |
7/16-14 | ✓ | 1.00 | 0.372 | 0.360 | 0.376 | 0.44 | |
1/2-13 | ✓ | 1.00 | 0.426 | 0.417 | 0.434 | 0.51 |
* also known as Pilot Hole Drill Ø
T* - Turning
Coil Insert Inch
Thread Pitch
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Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Inch coil insert: unified fine UNF - all dimensions in inches |
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#2-64 |
✓ | 0.30 | 0.093 | 0.089 | 0.095 | N/A | |
#3-56 |
✓ | 0.30 | 0.104 | 0.102 | 0.104 | N/A | |
#4-48 |
✓ | 0.40 | 0.120 | 0.116 | 0.123 | N/A | |
#6-40 |
✓ | 0.60 | 0.147 | 0.144 | 0.150 | N/A | |
#8-36 |
✓ | 0.60 | 0.173 | 0.170 | 0.177 | N/A | |
#10-32 |
✓ | 0.65 | 0.201 | 0.196 | 0.204 | N/A | |
1/4-28 |
✓ | 0.65 | 0.261 | 0.257 | 0.265 | N/A | |
5/16-24 |
✓ | 1.00 | 0.325 | 0.321 | 0.329 | N/A | |
3/8-24 |
✓ | 1.00 | 0.388 | 0.384 | 0.391 | N/A | |
#7/16-20 |
✓ | 1.00 | 0.452 | 0.448 | 0.456 | N/A | |
1/2-13 |
✓ | 1.00 | 0.426 | 0.417 | 0.434 | N/A | |
Inch coil insert: unified coarse UNC - all dimensions in inches |
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#2-56 |
✓ | 0.30 | 0.091 | 0.090 | 0.096 | N/A | |
#3-48 |
✓ | 0.40 | 0.107 | 0.105 | 0.110 | N/A | |
#4-40 |
✓ | 0.40 | 0.119 | 0.117 | 0.125 | N/A | |
#5-40 |
✓ | 0.40 | 0.132 |
0.131 |
0.137 | N/A | |
#6-32 |
✓ | 0.60 | 0.147 | 0.145 | 0.153 | N/A | |
#8-32 |
✓ | 0.60 | 0.173 | 0.171 | 0.178 | N/A | |
#10-24 |
✓ | 0.65 | 0.201 | 0.199 | 0.208 | N/A | |
#12-24 |
✓ | 0.65 | 0.227 | 0.225 | 0.234 | N/A | |
1/4-20 |
✓ | 0.65 | 0.266 | 0.261 | 0.270 | N/A | |
5/16-18 |
✓ | 1.00 | 0.332 | 0.324 | 0.334 | N/A | |
3/8-16 |
✓ | 1.20 | 0.397 | 0.389 | 0.399 | N/A | |
7/16-14 |
✓ | 1.20 | 0.453 | 0.453 | 0.464 | N/A | |
1/2-13 |
✓ | 1.20 | 0.531 | 0.515 | 0.531 | N/A |
* * also known as - Pilot Hole Drill Ø
Key Insert Inch
Thread Pitch
|
Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Inch key insert: Unified fine UNF - all dimensions in inches |
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#10-32 |
✓ | 0.600 | 0.162 | 0.160 | 0.164 | N/A | |
#12-28 |
✓ | 0.600 | 0.189 | 0.186 | 0.191 | N/A | |
1/4-28 |
✓ | 0.650 | 0.229 | 0.227 | 0.231 | N/A | |
Inch key insert: Unified coarse UNC - all dimensions in inches |
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#8-32 |
✓ | 0.400 | 0.135 | 0.133 | 0.137 | N/A | |
5/16-18 |
✓ | 0.650 | 0.274 | 0.271 | 0.276 | N/A | |
3/8-16 |
✓ | 1.000 | 0.334 | 0.331 | 0.336 | N/A | |
7/16-14 |
✓ | 1.000 | 0.399 | 0.396 | 0.401 | N/A | |
1/2-13 |
✓ | 1.000 | 0.455 | 0.452 | 0.457 | N/A |
* * also known as - Pilot Hole Drill Ø
Outside diameter inch
Thread Pitch
|
Process | Max Thread depth | CAD Ø | Eligible Ø | Clearance Ø | ||
---|---|---|---|---|---|---|---|
MILLING | TURNING | MIN | MAX | ||||
Inch outside diameter: unified fine UNF - all dimensions in inches |
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#5-44 |
✓ | 0.250 | 0.125 | 0.12 | 0.126 | 0.13 | |
#6-40 |
✓ | 0.280 | 0.138 | 0.132 | 0.139 | 0.14 | |
#8-36 |
✓ | 0.330 | 0.164 | 0.158 | 0.165 | 0.17 | |
#10-32 |
✓ | 0.380 | 0.190 | 0.183 | 0.191 | 0.19 | |
#12-28 |
✓ | 0.430 | 0.216 | 0.209 | 0.217 | 0.22 | |
1/4-28 |
✓ | 0.500 | 0.250 | 0.243 | 0.251 | 0.26 | |
5/16-24 |
✓ | 0.630 | 0.313 | 0.304 | 0.314 | 0.32 | |
3/8-24 |
✓ | 0.750 | 0.375 | 0.367 | 0.376 | 0.38 | |
7/16-20 |
✓ | 0.880 | 0.438 | 0.428 | 0.439 | 0.44 | |
1/2-20 |
M* | ✓ | 1.000 | 0.500 | 0.491 | 0.501 | 0.51 |
5/8-18 |
M* | ✓ | 1.250 | 0.625 | 0.615 | 0.626 | 0.64 |
3/4-16 |
M* | ✓ | 1.500 | 0.750 | 0.739 | 0.751 | 0.76 |
Inch outside diameter: fine or special - all dimensions in inches |
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#4-40 |
✓ | 0.22 | 0.112 | 0.106 | 0.113 | 0.12 | |
#5-40 |
✓ | 0.25 | 0.125 | 0.119 | 0.126 | 0.13 | |
#6-32 |
✓ | 0.28 | 0.138 | 0.131 | 0.139 | 0.14 | |
#8-32 |
✓ | 0.33 | 0.164 | 0.157 | 0.165 | 0.17 | |
#10-24 |
✓ | 0.38 | 0.190 | 0.182 | 0.191 | 0.19 | |
#12-24 |
✓ | 0.43 | 0.216 | 0.208 | 0.217 | 0.22 | |
1/4-20 |
✓ | 0.50 | 0.250 | 0.241 | 0.251 | 0.26 | |
5/16-18 |
✓ | 0.63 | 0.313 | 0.303 | 0.314 | 0.32 | |
3/8-16 |
✓ | 0.75 | 0.375 | 0.364 | 0.376 | 0.38 | |
7/16-14 |
✓ | 0.88 | 0.438 | 0.426 | 0.439 | 0.44 | |
1/2-13 |
M* | ✓ | 1.00 | 0.500 | 0.488 | 0.501 | 0.51 |
5/8-11 |
M* | ✓ | 1.25 | 0.625 | 0.611 | 0.626 | 0.64 |
3/4-10 |
M* | ✓ | 1.50 | 0.750 | 0.735 | 0.751 | 0.76 |
*also known as - Pilot Hole Drill Ø
M* On a 3 or 5-axis mill larger external threads can be cut with a ball nose cutter… refer to Special threads.