BIZOMAT MAKEOS · Manufacturing
Jaw Clutch Milling Set-up (Dividing-Head Angle and Indexing)
To mill the teeth of this jaw clutch on a dividing head, at what angle do I tilt the head, and what index setting moves from one tooth to the next?
Set-up for milling saw-tooth, V-shaped or straight-sided jaw clutch teeth: the angle to tilt the dividing head so a single- or double-angle cutter forms the tooth faces (as the clutch teeth dividing-head tool), the angle between teeth and the simple indexing setting for the tooth count (as the simple indexing tool), with notes for odd and even tooth counts.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Tooth form | choice | Form of the clutch teeth. |
| Number of teeth | Number of teeth on the clutch. | |
| Cutter angle (single) or included angle (double) | ° | Angle of the single-angle cutter, or the included angle of the double-angle cutter. |
| Dividing head worm ratio | :1 | Worm ratio of the dividing head. |
| Index plates available | choice | Index plates you have. |
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: Tooth form
- What it is
- The shape of the clutch teeth to be milled: saw-tooth cut with a single-angle cutter, V-shaped cut with a double-angle cutter, or straight-sided teeth cut with the head vertical.
- Units and format
- Choose one of 3 options from the list: Saw-tooth (single-angle cutter); V-shaped (double-angle cutter); Straight-sided teeth.
- Example
- The form opens with “Saw-tooth (single-angle cutter)” selected as a worked example. Choose the option that matches your case.
- Get it right
- Saw-tooth clutches drive in one direction only; V-shaped and straight-sided teeth drive both ways.
What this means: Number of teeth
- What it is
- The number of teeth around the face of the clutch, which sets the angle between teeth and the indexing between cuts.
- Units and format
- Enter a plain number with no unit. The form accepts 3 to 200. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More teeth reduce the angle between teeth and change both the dividing-head tilt and the index setting.
- Get it right
- For saw-tooth teeth this method needs at least 5 teeth; check whether the count is odd or even, as the cutting sequence differs.
What this means: Cutter angle (single) or included angle (double)
- What it is
- The angle of the single-angle cutter for saw-tooth teeth, or the included angle of the double-angle cutter for V-shaped teeth, from the cutter marking.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 20° to 120°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- For a double-angle cutter enter the full included angle, not half of it. It is not used for straight-sided teeth.
What this means: Dividing head worm ratio
- What it is
- The worm ratio of the dividing head: the number of crank turns that rotate the spindle once, stamped on the head or in its manual.
- Units and format
- Enter a number in :1: a ratio to one (type 3 for 3:1). The form accepts 1 :1 to 200 :1. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 40 :1 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Crank turns between teeth are this ratio divided by the number of teeth.
- Get it right
- Enter only the first number of the ratio, as in 40 for a 40:1 head.
What this means: Index plates available
- What it is
- The set of index plates you have for the dividing head, which decides which hole circles the tool can use for a fractional crank turn.
- Units and format
- Choose one of 2 options from the list: Brown & Sharpe plates 1–3; Cincinnati standard plate (both sides).
- Example
- The form opens with “Brown & Sharpe plates 1–3” selected as a worked example. Choose the option that matches your case.
- Get it right
- Choose the set actually in the workshop; if no circle suits, the tool reports that differential indexing is needed.
Method and formulas
- Saw-tooth: cos α = tan(360° ÷ N) ÷ (2 tan θ); V-shaped: cos α = tan(180° ÷ N) ÷ (2 tan(θ ÷ 2)); straight-sided: head vertical (as the clutch teeth dividing-head tool).
- Angle between teeth = 360° ÷ N.
- Crank turns = ratio ÷ N: whole turns plus holes in a circle where the remainder × circle ÷ N is whole (as the simple indexing tool).
- Example: tilt the head to 27.321° and index 8 whole turns between teeth.
Limitations
- Handbook set-up for the cutter on the clutch centre line.
- Simple indexing only.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Mill a replacement jaw or dog clutch
- Set the dividing head angle for saw-tooth clutch teeth
- Check whether the tooth count can be simply indexed
Who it is for
- Machinists
- Toolroom staff
- Maintenance fitters
What you get
- Dividing-head angle
- Angle between teeth
- Index setting
Interpreting the result
- With straight-sided teeth and an odd count, one pass cuts the sides of two teeth at once.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2452–2454, 2107–2121. Topic reference; no source tables or recommended settings are reproduced.
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Open the Jaw Clutch Milling Set-up (Dividing-Head Angle and Indexing) calculator