BIZOMAT MAKEOS · Quality
Go and No-Go Gauge Sizes
What sizes should the go and no-go plug or ring gauges have for this toleranced feature?
Go and no-go gauge sizes for a hole (plug gauges) or shaft (ring or snap gauges) by Taylor’s principle, with gauge tolerance and wear allowance placed inside the work tolerance.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Feature | choice | Hole or shaft. |
| Lower limit of size | mm | Smallest permitted size from the drawing. |
| Upper limit of size | mm | Largest permitted size from the drawing. |
| Gauge tolerance (% of work tolerance) | % | Gauge-maker’s tolerance as a share of the work tolerance (10% is a common rule; gauge standards set exact classes). |
| Wear allowance on go gauge (% of work tolerance) | % | Allowance on the go gauge for wear (0 if your system does not use one). |
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: Feature
- What it is
- Whether the gauges are for a hole, checked with plug gauges, or for a shaft, checked with ring or snap gauges.
- Units and format
- Choose one of 2 options from the list: Hole (plug gauges); Shaft (ring or snap gauges).
- Example
- The form opens with “Hole (plug gauges)” selected as a worked example. Choose the option that matches your case.
- Get it right
- The go gauge checks the maximum material limit: the smallest hole or the largest shaft.
What this means: Lower limit of size
- What it is
- The smallest size of the hole or shaft the drawing permits.
- 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 25 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter the limit itself, worked out from nominal size and tolerance.
What this means: Upper limit of size
- What it is
- The largest size of the hole or shaft the drawing permits.
- 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 25.021 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- It must be above the lower limit.
What this means: Gauge tolerance (% of work tolerance)
- What it is
- The manufacturing tolerance allowed on each gauge, expressed as a share of the work tolerance, placed inside the work limits.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 50%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger gauge tolerance leaves less of the work tolerance for production.
- Get it right
- Gauge standards set exact gauge tolerance classes; follow them where they apply.
What this means: Wear allowance on go gauge (% of work tolerance)
- What it is
- The extra material left on the go gauge so it can wear before it accepts an oversize hole or undersize shaft, as a share of the work tolerance.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 0% to 50%. 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
- A larger allowance moves the go gauge further inside the limits and leaves less tolerance for production.
- Get it right
- Enter 0 if your gauging system does not use a wear allowance.
Method and formulas
- Work tolerance T = upper − lower; gauge tolerance G = % × T; wear W = % × T.
- Hole: go plug = lower + W to lower + W + G; no-go plug = upper − G to upper.
- Shaft: go ring = upper − W − G to upper − W; no-go ring = lower to lower + G.
- All gauge tolerances lie inside the work limits, so a good gauge never accepts a bad part.
- Example: a 25–25.021 mm hole needs a go plug of 25.0011 to 25.0031 mm and a no-go plug of 25.0189 to 25.021 mm.
Limitations
- Inward (conservative) placement only; some standards allow other placements.
- Gauge form, temperature and measuring force must also be controlled.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Specify limit gauges for production
- Check a purchased gauge against the part limits
- Decide gauge tolerance and wear allowance
Who it is for
- Quality inspectors
- Toolmakers
- Metrology technicians
What you get
- Go gauge size range
- No-go gauge size range
- Work tolerance used by the gauges
Interpreting the result
- Calibrate gauges regularly and withdraw go gauges when worn past the low (or high) limit.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 661–663, 705–708. Topic reference; no source tables or recommended settings are reproduced.
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