# What is pitch diameter limit?

## What is pitch diameter limit?

Thread limit or pitch diameter limit is a standard used for classifying the tolerance of the thread pitch diameter for taps. For imperial, H or L limits are used which designate how many units of 0.0005 inch over or undersized the pitch diameter is from its basic value, respectively.

## What is a pitch diameter?

PITCH DIAMETER-The basic thread pitch diameter is the diameter where the thread thickness is equal to the space between the threads. If the flats at the top and bottom of the thread are the same, the pitch diameter will coincide with the middle of the sloping side of the thread.

What is 6g tolerance?

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 6H tolerance class?

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.

### Is the tolerance of pitch of a thread standarized?

As I was browsing ISO 965-1 it defines tolerances on a plenty of variables regarding metric threads, but it gives the pitch of the thread as a simple number from an allowed set ( 3 – 2 – 1,5 – 1– 0,75 – 0,5 – 0,35 – 0,25 – 0,2 ), and no tolerances on these are ever given.

How big is a standard pitch diameter plug?

Standard Pitch Diameter Chart 17 PRECISION GAGES FOR QUALITY ASSURANCE Ring Thread Gages and Setting Plugs NOMINAL SIZE X TOL. GO = – NO GO = + UNIFIED PITCH DIAMETER GO NOT GO GO NOT GO CLASS 2A CLASS 3A 9/ 16- 24 UNEF .5342 .5303 .5354 .5325 .0003 5/ 8- 11 UNC .5644 .5589 .5660 .5619 .0003 5/ 8- 18 UNF .5875 .5828 .5889 .5854 .0003 5/

#### What is the tolerance for Class 2A threads?

Allowance applied to Class 1A and 2A (male threads only) = 0.3 x Class 2A tolerance. There is no allowance provided on Class 3 threads or any Class of internal threads. There are also formulae in the standard for calculating major dia tolerance, minor dia tolerance, fiddle factors for class of fit, allowable lead error and flank angle error, etc.

#### What’s the thread tolerance for a tapped hole?

One practical problem that is often encountered is what thread tolerance to apply to a tapped hole. The standard tolerance classes of 6g for the bolt thread and 6H for the nut thread are typically included on a drawing as default.