BIZOMAT MAKEOS · Manufacturing
Knurling Blank Diameter for Tracking
What blank diameter lets this knurl track cleanly with a whole number of teeth?
Number of teeth produced on a blank for a diametral-pitch (inch) or circular-pitch (metric) knurl, and the nearest blank diameters that give a whole number of teeth for clean tracking.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Knurl system | choice | Inch knurls are specified by diametral pitch (64, 96, 128, 160); metric knurls by circular pitch. |
| Diametral pitch (teeth per inch of diameter) | 1/in | Diametral pitch of the knurl (inch system). |
| Circular pitch | mm | Circular pitch of the knurl (metric system). |
| Planned blank diameter | in or mm | Blank diameter you plan to use: inches for diametral pitch, millimetres for circular pitch. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Knurl system
- What it is
- Whether the knurl wheel is specified by diametral pitch (inch knurls) or by circular pitch (metric knurls).
- Units and format
- Choose one of 2 options from the list: Diametral pitch (inch); Circular pitch (metric).
- Example
- The form opens with “Diametral pitch (inch)” selected as a worked example. Choose the option that matches your case.
- Get it right
- The choice also sets the unit of the blank diameter: inches for diametral pitch, millimetres for circular pitch.
What this means: Diametral pitch (teeth per inch of diameter)
- What it is
- For an inch knurl, the number of knurl teeth per inch of the blank’s diameter, marked on the knurl wheel.
- Units and format
- Enter a number in 1/in: threads per inch. The form accepts 0.000001 1/in to 400 1/in. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 96 1/in as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Teeth on the blank rise in proportion to the diametral pitch.
- Get it right
- Used only for the diametral pitch system; it is ignored for metric circular pitch knurls.
What this means: Circular pitch
- What it is
- For a metric knurl, the distance between neighbouring teeth measured around the circumference, marked on the knurl wheel.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A finer circular pitch gives more teeth on the same blank.
- Get it right
- Used only for the circular pitch system; it is ignored for inch knurls.
What this means: Planned blank diameter
- What it is
- The diameter you intend to turn the blank to before knurling; the tool checks whether it gives a whole number of teeth and suggests the nearest ones that do.
- Units and format
- Enter a number in in or mm: in or mm. The form accepts 0.000001 in or mm to 10000 in or mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.75 in or mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter inches for a diametral pitch knurl and millimetres for a circular pitch knurl.
Method and formulas
- Diametral pitch: teeth = P × D; tracking blank = N ÷ P for a whole N.
- Circular pitch: teeth = π D ÷ t; tracking blank = N t ÷ π.
- Round the tooth count down and up to get the two nearest tracking diameters.
- Example: 96 DP on a 0.75 in blank gives 72 teeth; use 0.75 or 0.76042 in.
Limitations
- Straight knurling with the knurl axis parallel to the work; diagonal set-ups use P cos α.
- Material displacement raises the outside diameter; allow for it in the finished size.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a blank before knurling to avoid double tracking
- Choose a knurl pitch for a diameter
- Explain poor knurl patterns
Who it is for
- Machinists
- CNC programmers
- Manufacturing engineers
What you get
- Teeth on the planned blank
- Nearest smaller and larger blank diameters for a whole number of teeth
Interpreting the result
- Turn the blank to a tracking diameter within the tolerance the part allows.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 991–997. Topic reference; no source tables or recommended settings are reproduced.
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