KEVOS® MAKEOS · Threads
Angular Indexing on a Dividing Head
What crank movement turns the work through this angle on a dividing head?
Crank turns and holes for indexing an angle on a 40:1 (or other) dividing head, using the hole circle that gives the closest movement, with the resulting angular error.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Degrees | ° | Whole degrees of the angle. |
| Minutes | ′ | Additional minutes. |
| Worm ratio | :1 | Crank turns per spindle turn (40 on most heads, so one crank turn is 9°). |
| Index plates | choice | Index plates available. |
Method and formulas
- Crank turns = angle ÷ (360° ÷ ratio) (angle ÷ 9° for 40:1).
- For each hole circle, holes = fractional turns × circle, rounded; the circle with the smallest error is chosen.
- Error = obtained angle − required angle.
- Example: 17° 25′ needs 1 turns and 29 holes in the 31-hole circle, an error of 9.6774″.
Limitations
- Simple indexing only; very small angular steps need differential or vernier methods.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Mill features at a given angle with a dividing head
- Find the most accurate hole circle for an angle
- Check the angular error of an approximate setting
Who it is for
- Machinists
- Toolmakers
What you get
- Crank turns
- Best hole circle and holes
- Angle obtained and error
Interpreting the result
- If the error is too large, use the finer plate set or differential indexing.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2107–2121. Topic reference; no source tables or recommended settings are reproduced.
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