A go/no-go pin gauge is used to quickly check if a hole's size is within specified tolerance limits.
Understanding Go/No-Go Gauges
A go/no-go gauge consists of two parts: a "go" gauge and a "no-go" gauge. The "go" gauge represents the lower limit of the tolerance, while the "no-go" gauge represents the upper limit of the tolerance. The purpose is to verify a part is neither too small nor too big.
Step-by-Step Usage
Here’s how to properly use a go/no-go pin gauge to inspect hole size:
- Start with the Go Gauge:
- Select the gauge set that corresponds to the desired hole size tolerance.
- Attempt to insert the "go" gauge into the hole.
- Interpretation: If the "go" gauge fits easily into the hole, it means that the hole is at least as big as the minimum allowable size. According to the reference, “if the gage can be entered into the hole, then the hole is considered to be above its low limit.”
- Proceed with the No-Go Gauge:
- Next, attempt to insert the "no-go" gauge into the same hole.
- Interpretation: If the "no-go" gauge does not fit into the hole, it means that the hole is not too large. This is the desired outcome. However, if the “no-go” gauge enters the hole, “than the hole is too big”, according to the reference.
- Accept or Reject:
- Acceptance: If the "go" gauge fits, and the "no-go" gauge does not fit, the hole is within the acceptable size range.
- Rejection: If either the "go" gauge does not fit or the "no-go" gauge does fit, the hole is outside the acceptable tolerance and should be rejected.
Example
Let's say you have a hole with a specified diameter between 10.00 mm and 10.05 mm.
- The "go" pin gauge would be slightly larger than 10.00 mm.
- The "no-go" pin gauge would be slightly smaller than 10.05 mm.
- If the "go" pin gauge slides in, and the "no-go" pin gauge does not fit, the hole is deemed to be within tolerance.
Practical Tips
- Cleanliness: Ensure both the gauge and the hole are clean from debris.
- Alignment: Align the gauge straight with the hole to prevent it from getting stuck.
- Gentle Insertion: Do not force either gauge; they should insert with slight pressure.
- Proper Storage: When not in use, always store the gauge set in its designated container to prevent damage.
Table Summary
| Gauge | Test | Interpretation | Result |
|---|---|---|---|
| "Go" Gauge | Inserts into the hole | Hole is at or above the minimum acceptable size | Pass for lower limit |
| "Go" Gauge | Fails to insert into the hole | Hole is below the minimum acceptable size | Fail |
| "No Go" Gauge | Fails to insert into the hole | Hole is within the maximum acceptable size | Pass for upper limit |
| "No Go" Gauge | Inserts into the hole | Hole is over the maximum acceptable size | Fail |
