Net price: €18.42
Description
Internal thread gauge according to PN-ISO 1502:1998
| TECHNICAL DATA | |
|---|---|
| Thread type | ISO metric (M) — fine pitch |
| Thread size | M12x0.75 |
| Thread pitch | 0.75 mm (fine) |
| Tolerance class | 6H |
| Gauge type | GO / NO-GO |
| Material | Tool steel, hardened |
| Hardness | 58-62 HRC |
| Standard | PN-ISO 1502:1998 |
| Manufacturer | Varel |
Thread plug gauge M12x0.75 6H shows within seconds whether a tapped hole is within tolerance 6H. The GO end GO must enter by hand through the full thread length. The NO-GO end NO-GO must not enter by more than 2 threads, counted when unscrewing the gauge. If both conditions are met, the thread is acceptable.
Holes of this size carry substantial loads: machine housings, flanges and steel structures. An out-of-tolerance thread does not reveal itself immediately — only after several operating cycles, when the joint starts losing clamping force. The fine pitch of 0.75 mm gives a shallower profile and less clearance than the coarse pitch of 1.75 mm. The gauge fits only the thread M12x0.75 — M12 with a 1.75 mm pitch requires a separate gauge. For reference: the internal thread minor diameter M12x0.75 is 11.188 mm, while the gauge checks the pitch diameter, which is the dimension halfway up the thread profile.
How to check an internal thread correctly
Screwing into the thread — must enter
Screwing into the thread — no more than 2 turns
Tolerance: 6H OK
If the end GO enters, and the end NO-GO does not enter — the thread meets the requirements of class 6H according to PN-ISO 1502:1998
No color marking — it has a longer thread and GO marked on the handle. It checks minimum internal thread dimensions. It must screw in freely along the full thread length. If it does not enter — the thread is undersized (the workpiece requires rework).
Marked with a red ring. Checks maximum thread dimensions. It must not screw in more than 2 threads, with turns counted when unscrewing the gauge, not when screwing it in. If it goes farther — the thread is too loose and the part does not meet the tolerance class. For a thread 3 turns long or shorter, the NO-GO end must not pass all the way through.
Comparison of tolerance classes for an M12x0.75 internal thread
Basic pitch diameter D2 for the thread M12x0.75 is 11.513 mm. In classes designated H, this is also the minimum dimension — the tolerance extends upward only.
| Class | D2 nominal [mm] | D2 permissible [mm] | Tolerance zone | Application | Status |
|---|---|---|---|---|---|
| 4H | 11.513 mm | 11.513 – 11.603 mm | 0.090 mm | Precision | |
| 5H | 11.513 mm | 11.513 – 11.625 mm | 0.112 mm | Close | |
| 6H | 11.513 mm | 11.513 – 11.653 mm | 0.140 mm | Standard | THIS PRODUCT |
| 7H | 11.513 mm | 11.513 – 11.693 mm | 0.180 mm | Coarse |
The full range of class 6H for the thread M12x0.75 is 0.140 mm: from 11.513 to 11.653 mm. Class 6H corresponds to a typical nut and a standard machine tap — it is selected for class 6g bolts. Classes 4H and 5H reduce clearance where the thread guides a component; 7H leaves an allowance for electroplating. The values in the table refer to pitch diameter D2, not the tap drill diameter.
Set contents and gauge storage
INCLUDED:
| ✓ | M12x0.75 6H GO/NO-GO thread plug gauge |
| ✓ | Size marking on the plug |
STORAGE:
| ✓ | Store in a dry place, in its case |
| ✓ | Protect against dropping — impact damages the thread |
| ✓ | Apply rust-preventive oil periodically |
6H is the most commonly used internal thread tolerance class according to ISO 965-1. The digit 6 specifies the tolerance grade (zone width), and the letter H indicates the tolerance zone position (lower deviation = 0). Class 6H provides a standard fit with class 6g bolts.
The end GO (GO, with the longer thread) must enter freely along the full thread length. The end NO-GO (NO-GO, red) should not screw in more than 2 turns (counted when unscrewing). Both conditions must be met simultaneously for the thread to be considered acceptable according to PN-ISO 1502:1998.
Gauge wear is checked by periodic measurement at intervals based on usage intensity (ISO 1502, clause 7.2.1); the standard specifies neither the number of measurements nor a fixed interval. A worn gauge gives false positive results — the NO-GO end starts entering the thread. The gauge should be verified periodically using setting gauges.
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| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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