Thread tolerance
Thread tolerance
(OP)
Hi,
What is the advantage of having a class-3B tread compared to a normal thread?
Thanks & Regards.
What is the advantage of having a class-3B tread compared to a normal thread?
Thanks & Regards.
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RE: Thread tolerance
The class of a thread determines the tolerance allowed when making the thread. All nuts and bolts no matter what class they are made to will screw onto each other. The difference will be the clearance between the mating parts.
RE: Thread tolerance
of the id or minor diameter of the internal
thread resulting in sometimes requiring
special tap drill diameters to maintain the
closer tolerance on the id for the 2B threads.
3B threads are easier to assemble which may
be the major reason for using them with 2A
screws or bolts.
RE: Thread tolerance
Usually if the class is not specified, is there a default class to follow?
for eg, if it is just stated the thread as 1/2-13UNC instead of 1/2-13UNC-3B?
Thanks & Regards.
RE: Thread tolerance
For most normal circumstances I used Class 2 threads, e.g.1/2-13 2B
I believe most SHCS are made to the Class 2 tolerance, correct me if I'm wrong guys.
Alan M. Etzkorn

Project Develpment Engineer
Wabash National Corp.
www.wabashnational.com
RE: Thread tolerance
Most industrial applications call
for 2B threads.
RE: Thread tolerance
I think you mixed up your 2Bs and 3Bs in typing.
The minor diamter tolerance is closer (smaller) for 3B (not 2B) internal threads. The minimum minor diamter is the same; the maximum minor diameter is slightly larger on 2B threads (compared to 3B).
The greater internal clearances afforded by 2B threads makes them easier to assemble...
Most commercial hardware threads are (understandably) Class 2; most aerospace hardware threads are Class 3.
RE: Thread tolerance
RE: Thread tolerance
Metric is a whole 'nother can of worms depending on what 'standard' you want to follow.
Dick
RE: Thread tolerance