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M40X2 ring gauge 6g Go
780254
€103.58 tax inc.
Net price: €84.21
Description
ThreadM40 × 2
Tolerance class6g
TypeGO
Hardness58–62 HRC
Technical specifications of the M40 × 2 thread ring gauge
Gauge specifications according to ISO 965-1
| Technical data | |
|---|---|
| Gauge type | GO thread ring gauge |
| Thread | M40 × 2 mm |
| Nominal diameter | Ø40.000 mm |
| Pitch diameter (d2) | 38.701 mm |
| Thread pitch | 2 mm |
| Tolerance class | 6g |
| Material | Tool steel, hardened |
| Hardness | 58–62 HRC |
| Standard | ISO 965-1 / DIN 13 |
| Manufacturer | Varel |
Operating principle of the GO gauge
Gauge for M40x2 external threads
GO ring gauge GO M40x2 6g checks whether the external thread is oversized — it must screw on by hand along the full length. This is a single-limit check: it detects excess material but will not detect an undersized thread. That requires the ring gauge NO-GO, ordered separately: it may screw onto the thread no more than 2 threads, counted when unscrewing.
Studs and bolts of this size are used in flange and foundation joints. A nut that is hard to turn usually indicates an out-of-tolerance thread, not contamination. For reference: the thread minor diameter M40x2 is 37.546 mm — this cross section determines the bolt's strength, while the gauge checks the pitch diameter.
The GO gauge checks the maximum material limit of the external thread, checking pitch diameter, pitch and thread profile simultaneously. If the GO gauge does not screw onto the thread — the part is nonconforming (thread oversized, out of tolerance). Complete thread inspection also requires a gauge NO-GO, which checks the minimum material limit.
Tolerance classes for an M40 × 2 external thread
Comparison of classes according to ISO 965-1
Comparison of classes 4g, 6g, 6e and 8g
Basic pitch diameter d2 for the thread M40x2 is 38.701 mm. The deviations in the table are measured downward from this value.
| Class | d2 nominal [mm] | d2 permissible [mm] | Tolerance zone | Application | Status |
|---|---|---|---|---|---|
| 4g | 38.701 mm | 38.557 – 38.663 mm | 0.106 mm | Precision fit | |
| 6g | 38.701 mm | 38.493 – 38.663 mm | 0.170 mm | Standard fit (bolts) | THIS PRODUCT |
| 6e | 38.701 mm | 38.460 – 38.630 mm | 0.170 mm | Clearance fit (coatings) | |
| 8g | 38.701 mm | 38.398 – 38.663 mm | 0.265 mm | Coarse fit |
The full range of class 6g for the thread M40x2 is 0.170 mm: from 38.493 to 38.663 mm. Class 6g is the standard for general-purpose bolts — it mates with 6H nuts. Classes 4g and 5g reduce clearance in guiding joints, while 6e and 8g leave room for electroplating. The values in the table are pitch diameter d2, measured at half the profile height, not the thread major diameter.
Thread inspection process
Correct use of GO/NO-GO gauges
Thread inspection M40x2 6g
1 GO gauge
screws on: YES
2 NO-GO gauge
screws on: NO — max. 2 turns
✓ Conforming thread
class: 6g OK
Both conditions must be met simultaneously. Standard: ISO 965-1
Usage guidelines
Proper storage and use
Store the gauge in a dry place, protected with rust-preventive oil. Before measurement, remove chips and burrs from the thread being inspected. Screw the gauge on by hand — never use wrenches or force. The calibration interval is determined by the user based on usage intensity — ISO 1502 (clause 7.2.1) requires periodic gauge measurement but specifies neither the interval nor the number of measurements.
Varel gauge features:
| ✓ | Alloy tool steel hardened to 58–62 HRC |
| ✓ | Ground thread profiles for high accuracy |
| ✓ | Thread, tolerance class and type (GO) marked on the ring |
| ✓ | Compliance with ISO 965-1 / DIN 13 |
Frequently asked questions
The GO thread ring gauge is used to inspect M40x2 external threads of tolerance class 6g. It verifies that the pitch diameter, pitch and thread profile are within permissible limits. The gauge should screw freely onto the full length of the thread being inspected.
The GO gauge checks the maximum material limit — it must screw onto the thread. The NO-GO gauge checks the minimum limit — it should not screw on more than 2 turns. Both gauges are required for complete inspection of an M40x2 6g thread.
ISO 1502 (clause 7.2.1) requires gauge wear to be checked by periodic measurement at intervals based on usage intensity, but specifies neither the interval nor the number of measurements — these are determined by the user as part of measuring equipment control. Calibration is performed by an accredited metrology laboratory. Between calibrations, it is advisable to check the gauge using a setting plug gauge.
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All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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