KEVOS® MAKEOS · Manufacturing
Polygon Milling Set-up (Stock Size, Depth of Cut, Indexing)
To mill a hexagon (or any regular polygon) on round bar, what stock diameter do I need for sharp corners, how deep is each flat, and what index setting moves between flats?
Set-up for milling a regular polygon on round stock with a dividing head: side length, across-flats and across-corners sizes (as the regular polygon tool), whether the stock is large enough for full corners, depth of cut to each flat and the passes for your largest depth of cut, and the simple indexing setting between flats (as the simple indexing tool).
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Number of sides | Number of flats on the polygon. | |
| Across flats | mm | Distance across opposite flats (or a flat and the opposite corner for odd numbers, measured as the inscribed circle diameter). |
| Round stock diameter | mm | Diameter of the round bar. |
| Largest depth of cut per pass | mm | Deepest cut you take in one pass. |
| Dividing head worm ratio | :1 | Worm ratio of the dividing head. |
| Index plates available | choice | Index plates you have. |
Method and formulas
- Side = across flats × tan(180° ÷ n); across corners = side ÷ sin(180° ÷ n) (as the regular polygon tool).
- Full corners need stock ≥ across corners; depth of cut to each flat = (stock − across flats) ÷ 2; passes = ⌈depth ÷ largest cut⌉.
- Crank turns between flats = ratio ÷ n (as the simple indexing tool).
- Example: a 24 mm hexagon needs 27.713 mm across corners; cut 3 mm deep in 2 passes; index 6 turns and 10 holes in the 15-hole circle.
Limitations
- Sharp corners; chamfered corners allow smaller stock.
- Simple indexing only.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Mill a hexagon or square on a bar end
- Choose stock size for a polygon
- Prepare the index setting for flats
Who it is for
- Machinists
- Toolroom staff
- Maintenance fitters
What you get
- Side, across-flats and across-corners sizes
- Stock check, depth of cut and passes
- Index setting
Interpreting the result
- Stock between the across-flats and across-corners sizes gives a polygon with rounded corners, which is often acceptable for nuts and keys.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 76, 81–82, 2107–2121. Topic reference; no source tables or recommended settings are reproduced.
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Open the Polygon Milling Set-up (Stock Size, Depth of Cut, Indexing) calculator
