What is G and H in thread?

Published by Charlie Davidson on

What is G and H in thread?

“G” designates Ground Thread. “H” designates the pitch diameter is on high side of basic. These two letters (GH) are followed by a numeral indicating the Tolerance of Pitch diameter oversize.

What is M12 thread size?


Tap size Basic major dia (mm) Basic major dia (inch)
M8 x 1 8mm .3150
M10 x 1.5 10mm .3937
M10 x 1.25 10mm .3937
M12 x 1.75 12mm .4724

What does the H stand for on a tap?

It is important to remember that classes of thread actually represents manufacturing tolerances. Ground thread tap limits are designated by the letter H (high) above basic pitch diameter, or L (low) below basic pitch diameter, and these numbers establish the tolerance range in relation to basic pitch diameter.

What does 6g mean in threads?

Screws threads with identical external tolerances and pitch tolerances are expressed with a single tolerance letter and number. For instance, a screw with a 6g major diameter tolerance and a 6g pitch diameter tolerance would simply be written as “6g”.

What is thread tolerance 6H and 6g?

The 5g indicates the tolerance class for the pitch diameter and 6g is the tolerance class for the major diameter. For example: M12 x 1 – 6H/5g6g indicates a tolerance class of 6H for the nut (female) thread and a 5g tolerance class for the pitch diameter with a 6g tolerance class for the major diameter.

What is a Class 2 thread?

Classes 2A and 2B offer optimum thread fit that balances fastener performance, manufacturing, economy, and convenience. Nearly 90% of all commercial and industrial fasteners use this class of thread fit. Classes 3A and 3B are suited for close tolerance fasteners.

Is M12 the same as 12mm?

Yes. M12 is a 12mm diameter thread. You have to be sure the thread pitch measured in threads per millimeter (1.5 here) is the same as what u need.

What is standard M12 thread pitch?

Metric clearance and tapping drill hole sizes.

Size Clearance Hole mm Tapping Drill (fine pitch)
M10 11 9.0 or 8.75 mm
M12 14 10.5 mm
M16 18 16.5 mm
M20 22 20.5 mm

What is the difference between NF and NC threads?

The difference between NC and NF is the pitch. Coarse threads have a larger pitch ( fewer threads per inch, or a bigger distance between the threads) compared to fine threads.

What is 6H thread tolerance?

A class of thread fit roughly equivalent to 2A/2B is “6g/6H”, which means an external thread with tolerance grade of 6 and position g, and an internal thread of tolerance class 6 with position H.

What are the dimensions of a metric screw thread?

This Standard contains general metric standards for a 60-degree symmetrical screw thread with a basic ISO 68 designated profile. Max. Max. Tol. GENERAL NOTE: All dimensions are in millimeters.

Is the ANSI b1.13m thread interchangeable with other threads?

Threads produced to this Standard ANSI/ASME B1.13M are fully interchangeable with threads conforming to other National Standards that are based on ISO 68 basic profile and ISO 965/1 tolerance practices.

What kind of thread is used for screws?

The ISO metric screw threads are the worldwide most commonly used type of general-purpose screw thread. They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947.

How is a fit between threaded parts indicated?

A fit between threaded parts is indicated by the nut thread tolerance designation followed by the bolt thread tolerance designation separated by a slash. For example: M12 x 1 – 6H/5g6g indicates a tolerance class of 6H for the nut (female) thread and a 5g tolerance class for the pitch diameter with a 6g tolerance class for the major diameter.

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