BIZOMAT MAKEOS · Quality
Vee Groove Pin Inspection (Pin Height at Nominal and Limits, Groove Width from the Reading)
For a vee groove checked with a pin, what height should the pin stand above the surface, and what groove width does my measured height give?
Inspection of a vee groove (or dovetail-like vee slot) by a gauge pin: the distance from the top surface to the pin centre, the depth to the vee apex and the pin height above the surface at the nominal width (as the vee groove pin tool), the readings at the width limits, and the groove width worked back from a measured pin height, with the check that the pin touches the flanks below the top edges.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Included groove angle | ° | Included angle of the vee. |
| Nominal groove width at the top surface | mm | Width of the groove at the top surface on the drawing. |
| Width tolerance (±) | mm | Plus-or-minus tolerance on the width. |
| Pin diameter | mm | Diameter of the gauge pin. |
| Measured pin height above the surface | mm | Height of the top of the pin above the surface (negative if below). |
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: Included groove angle
- What it is
- The full angle between the two flanks of the vee groove, measured across the groove.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 1° to 179°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 90° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter the included angle, not the half angle from the centre line.
What this means: Nominal groove width at the top surface
- What it is
- The width of the groove where its flanks meet the top surface, as given on the drawing. The tool works out the theoretical apex depth from it.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the width at the sharp edges, not after any chamfer or edge break.
What this means: Width tolerance (±)
- What it is
- The plus-or-minus tolerance on the groove width from the drawing. The tool gives the pin heights at both width limits.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 100 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.05 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- For an unequal tolerance, enter the smaller side or run the tool twice with adjusted widths.
What this means: Pin diameter
- What it is
- The diameter of the gauge pin or roll laid in the groove so it touches both flanks.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the certified size of the pin; the tool rejects a pin so large that it rests on the groove edges.
What this means: Measured pin height above the surface
- What it is
- The measured height of the top of the pin above the top surface, read with a height gauge or indicator. Enter a negative value if the pin top sits below the surface.
- Units and format
- Enter a number in mm: millimetres. The form accepts -10000 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2.25 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher reading means a narrower groove: the width worked back falls as the reading rises.
- Get it right
- Measure to the top of the pin, not its centre.
Method and formulas
- Pin centre above the apex = (d ÷ 2) ÷ sin (A ÷ 2); apex depth = (W ÷ 2) ÷ tan (A ÷ 2); height above surface = d ÷ 2 + centre − depth (as the vee groove pin tool).
- Readings at the limits use W ± tolerance.
- Width from a reading = 2 tan (A ÷ 2) × (d ÷ 2 + centre − measured height).
- Example: the pin should stand 2.2426 mm above the surface; 2.25 mm gives a width of 9.9853 mm.
Limitations
- Sharp vee with straight flanks; a rounded apex does not matter as long as the pin touches the flanks.
- The angle is taken as correct; check it separately, as an angle error looks like a width error.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Inspect a vee groove width with a pin and height gauge
- Choose a pin that touches the flanks properly
- Set the readings for a vee slot on a fixture
Who it is for
- Inspectors
- Machinists
- Toolmakers
What you get
- Pin centre, apex depth and height at nominal
- Readings at the width limits
- Width from the reading and the decision
Interpreting the result
- A pin that sits about half its diameter above the surface gives a good reading; one that rests on the edges reads nothing useful.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 682–691. Topic reference; no source tables or recommended settings are reproduced.
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