Basic Thread Dimensions
| Property | mm | Inch |
|---|---|---|
| Nominal Diameter | 1.8 | 0.0709 |
| Pitch (Distance) | 0.35 | 0.0138 |
| Pitch Diameter | 1.573 | 0.0619 |
| Minor Diameter | 1.421 | 0.0559 |
| Thread Height | 0.189 | 0.0074 |
| Addendum | 0.114 | 0.0045 |
| Crest (External) Root (Internal) |
0.044 | 0.0017 |
| Tap Drill Size (75% depth) |
1.46 | 0.057 |
| Lead Angle (Single Start) |
4.05° | |
| Thread Family | Metric Coarse Pitch (MC) | |
| Relevant Standards | ISO 68-1, ISO 9651-1, ISO 965-2, ISO 261,DIN 13 | |
| Equivalent Inch Thread | #1 - 72 UNF |
For more threading data scroll down, or use the Thread Calculator
Table of Content
- Limit of dimensions for all thread classes
- Tap drill sizes
- Cutting conditions for External Threading (Thread Turning & Thread Milling)
- Cutting conditions for Internal Threading (Thread Turning, Thread Milling & Tapping)
- Over wire measurements
M1.8 Possible Thread Classes
M1.8 4g (External)
* Permisable values for thread Class 4g
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| d | Major Diameter | 1.728 - 1.781 | 0.068 - 0.0701 |
| d2 | Pitch Diameter | 1.514 - 1.554 | 0.0596 - 0.0612 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.093 | 0.0017 - 0.0037 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 4h (External)
* Permisable values for thread Class 4h
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0 (Ref) | 0 (Ref) |
| d | Major Diameter | 1.747 - 1.8 | 0.0688 - 0.0709 |
| d2 | Pitch Diameter | 1.533 - 1.573 | 0.0604 - 0.0619 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.093 | 0.0017 - 0.0037 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 6g (External)
* Permisable values for thread Class 6g
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| d | Major Diameter | 1.696 - 1.781 | 0.0668 - 0.0701 |
| d2 | Pitch Diameter | 1.491 - 1.554 | 0.0587 - 0.0612 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.107 | 0.0017 - 0.0042 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 6h (External)
* Permisable values for thread Class 6h
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0 (Ref) | 0 (Ref) |
| d | Major Diameter | 1.715 - 1.8 | 0.0675 - 0.0709 |
| d2 | Pitch Diameter | 1.51 - 1.573 | 0.0594 - 0.0619 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.107 | 0.0017 - 0.0042 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 5g4g (External)
* Permisable values for thread Class 5g4g
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| d | Major Diameter | 1.728 - 1.781 | 0.068 - 0.0701 |
| d2 | Pitch Diameter | 1.504 - 1.554 | 0.0592 - 0.0612 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.099 | 0.0017 - 0.0039 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 5h4h (External)
* Permisable values for thread Class 5h4h
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0 (Ref) | 0 (Ref) |
| d | Major Diameter | 1.747 - 1.8 | 0.0688 - 0.0709 |
| d2 | Pitch Diameter | 1.523 - 1.573 | 0.06 - 0.0619 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.099 | 0.0017 - 0.0039 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 5g6g (External)
* Permisable values for thread Class 5g6g
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| d | Major Diameter | 1.696 - 1.781 | 0.0668 - 0.0701 |
| d2 | Pitch Diameter | 1.504 - 1.554 | 0.0592 - 0.0612 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.099 | 0.0017 - 0.0039 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 7g6g (External)
* Permisable values for thread Class 7g6g
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| d | Major Diameter | 1.696 - 1.781 | 0.0668 - 0.0701 |
| d2 | Pitch Diameter | 1.474 - 1.554 | 0.058 - 0.0612 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.116 | 0.0017 - 0.0046 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 7h6h (External)
* Permisable values for thread Class 7h6h
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| es | Allowance | 0 (Ref) | 0 (Ref) |
| d | Major Diameter | 1.715 - 1.8 | 0.0675 - 0.0709 |
| d2 | Pitch Diameter | 1.493 - 1.573 | 0.0588 - 0.0619 |
| R | Root Radius | 0.044 (Min) | 0.0017 (Min) |
| C | Root Truncation | 0.044 - 0.116 | 0.0017 - 0.0046 |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 4H (Internal)
* Permisable values for thread Class 4H
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| EL | Allowance | 0 (Ref) | 0 (Ref) |
| D1 | Minor Diameter | 1.421 - 1.484 | 0.0559 - 0.0584 |
| D2 | Pitch Diameter | 1.573 - 1.626 | 0.0619 - 0.064 |
| D | Major Diameter | 1.8 (Min) | 0.0709 (Min) |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 5H (Internal)
* Permisable values for thread Class 5H
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| EL | Allowance | 0 (Ref) | 0 (Ref) |
| D1 | Minor Diameter | 1.421 - 1.501 | 0.0559 - 0.0591 |
| D2 | Pitch Diameter | 1.573 - 1.64 | 0.0619 - 0.0646 |
| D | Major Diameter | 1.8 (Min) | 0.0709 (Min) |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 5G (Internal)
* Permisable values for thread Class 5G
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| EL | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| D1 | Minor Diameter | 1.44 - 1.52 | 0.0567 - 0.0598 |
| D2 | Pitch Diameter | 1.592 - 1.659 | 0.0627 - 0.0653 |
| D | Major Diameter | 1.8 (Min) | 0.0709 (Min) |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 6H (Internal)
* Permisable values for thread Class 6H
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| EL | Allowance | 0 (Ref) | 0 (Ref) |
| D1 | Minor Diameter | 1.421 - 1.521 | 0.0559 - 0.0599 |
| D2 | Pitch Diameter | 1.573 - 1.658 | 0.0619 - 0.0653 |
| D | Major Diameter | 1.8 (Min) | 0.0709 (Min) |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
M1.8 6G (Internal)
* Permisable values for thread Class 6G
| # | Description | Value (mm) | Value (Inch) |
|---|---|---|---|
| EL | Allowance | 0.019 (Ref) | 0.0007 (Ref) |
| D1 | Minor Diameter | 1.44 - 1.54 | 0.0567 - 0.0606 |
| D2 | Pitch Diameter | 1.592 - 1.677 | 0.0627 - 0.066 |
| D | Major Diameter | 1.8 (Min) | 0.0709 (Min) |
| LE | Normal Length of Engagement | 0.8 - 2.6 | 0.0315 - 0.1024 |
* Back to Thread Class Selection
Tap Drill Sizes for M1.8
- If not specified, assume a thread depth of 75%.
- You can learn more about thread depth in tapping here.
- To get the tap drill size in other depths, use our Tap Drill Size Calculator .
| Thread Depth | Tap Drill Size (Inch) | Tap Drill Size (mm) |
|---|---|---|
| 55% | 0.061 | 1.55 |
| 60% | 0.060 | 1.53 |
| 65% | 0.059 | 1.50 |
| 70% | 0.058 | 1.48 |
| 75% | 0.057 | 1.46 |
| 80% | 0.057 | 1.44 |
| 85% | 0.056 | 1.41 |
Over Wire Measurements for M1.8
* OverWire is a measuring method to obatin the pitch diameter of threads. It is mostly used when a manufacturer does not have a Go/Nogo gauge for a thread. You can learn more about it here
| mm | Inch | |
|---|---|---|
| Permissible Wire Diameter Range | 0.177 - 0.354 | 0.007 - 0.0139 |
| Ideal Wire Diameter | 0.202 | 0.008 |
| Possible Wires From Standard Sets |
* 0.202 * 0.231 * 0.26 * 0.289 * 0.346 |
* 0.0072 * 0.008 * 0.009 * 0.0103 * 0.0116 * 0.012 * 0.0131 |
Once you know your wire diameter, you need to find out what is the premissable Measurement for your pitch diameter (Depending on the class). Use our Over Wire Calculator to find out!
