Thread Gage Tolerances ?Who?s The Authority??

M

mlaurie

Who is the recognized Body / Authority that establishes ?Pitch Diameter? tolerances for thread gages?
For example: a 5/16-18 2B Go / No-Go thread gage has a Class X major pitch dia tolerance of +/- .0002.
Who established that? and how do I reference that in my measuring system for ?Acceptance Criteria? for gages?
I got hit on a recent Stage 2 and need to have it covered at close down.
As always, many thanks
 

Stijloor

Leader
Super Moderator
Who is the recognized Body / Authority that establishes ?Pitch Diameter? tolerances for thread gages?
For example: a 5/16-18 2B Go / No-Go thread gage has a Class X major pitch dia tolerance of +/- .0002.
Who established that? and how do I reference that in my measuring system for ?Acceptance Criteria? for gages?
I got hit on a recent Stage 2 and need to have it covered at close down.
As always, many thanks

For starters, you may want to scroll down this page and check the links.
 

AndyN

Moved On
Who is the recognized Body / Authority that establishes ?Pitch Diameter? tolerances for thread gages?
For example: a 5/16-18 2B Go / No-Go thread gage has a Class X major pitch dia tolerance of +/- .0002.
Who established that? and how do I reference that in my measuring system for ?Acceptance Criteria? for gages?
I got hit on a recent Stage 2 and need to have it covered at close down.
As always, many thanks

When you say you "got hit on a stage 2" can you give us more information? Was this a non-conformity? If so, what was the exact reported non-conformity statement? Before you try to fix something, it's useful to know exactly what's (supposed) to be fixed...
 

Jim Wynne

Leader
Admin
Who is the recognized Body / Authority that establishes ?Pitch Diameter? tolerances for thread gages?
For example: a 5/16-18 2B Go / No-Go thread gage has a Class X major pitch dia tolerance of +/- .0002.
Who established that? and how do I reference that in my measuring system for ?Acceptance Criteria? for gages?
I got hit on a recent Stage 2 and need to have it covered at close down.
As always, many thanks

Unified thread classification and tolerances are currently controlled by ASME/ANSI in the U.S. See also [Wikipedia reference-linkScrew_thread#History_of_standardization .
 
M

mlaurie

The Hit Is.
Process for control of monitoring and measuring equipment is ineffective.
4) There was no acceptance/out of tolerance criteria defined for calibration of the Vision System #G1.

There were no tolerence limits specified to say the gage is acceptable if it is within the tolerance range.
So I looked up ranges for all my thread gages, they fall in Class "X". I see references to ansi/asme b89.1.6m but can non download the document.
 
J

JAltmann

The Hit Is.
Process for control of monitoring and measuring equipment is ineffective.
4) There was no acceptance/out of tolerance criteria defined for calibration of the Vision System #G1.

There were no tolerence limits specified to say the gage is acceptable if it is within the tolerance range.
So I looked up ranges for all my thread gages, they fall in Class "X". I see references to ansi/asme b89.1.6m but can non download the document.

The finding seems to be referencing the equipment used to inspect the thread plug. If this is the case is the Vision System calibrated? If yes the cal. cert. for the Viion Sys. should list the acceptance criteria.
 

Jim Wynne

Leader
Admin
The Hit Is.
Process for control of monitoring and measuring equipment is ineffective.
4) There was no acceptance/out of tolerance criteria defined for calibration of the Vision System #G1.

There were no tolerence limits specified to say the gage is acceptable if it is within the tolerance range.
So I looked up ranges for all my thread gages, they fall in Class "X". I see references to ansi/asme b89.1.6m but can non download the document.

This finding seems to be about the tolerance control of the vision system itself, not thread gages.
 
M

mlaurie

The vision system (CMM) is calibrated. But it's the tolerance of the thread gage I need. it falls under Class "X" +/- .0003 for most gages but I can't find the document or authority to make that statement in my system. I understand the MIL specs don't apply anymore and the ansi/asme specs seems diffacult to find and / or download.
 

Jim Wynne

Leader
Admin
The Hit Is.
Process for control of monitoring and measuring equipment is ineffective.
4) There was no acceptance/out of tolerance criteria defined for calibration of the Vision System #G1.

There were no tolerence limits specified to say the gage is acceptable if it is within the tolerance range.
So I looked up ranges for all my thread gages, they fall in Class "X". I see references to ansi/asme b89.1.6m but can non download the document.

The finding seems to be referencing the equipment used to inspect the thread plug. If this is the case is the Vision System calibrated? If yes the cal. cert. for the Viion Sys. should list the acceptance criteria.

This finding seems to be about the tolerance control of the vision system itself, not thread gages.

You quoted an audit finding that addresses the tolerance control for the vision system. The audit finding doesn't say anything about thread gages. What is the relevance of the tolerance control for the vision system? The way the finding reads, if you're using the vision system to calibrate thread gages and the calibration tolerance of the vision system hasn't been established or documented, the tolerance class of the thread gages is irrelevant, at least at this point.

If you need controlled reference material for threads, you're most likely going to have to pay for it. The standard you reference, ANSI/ASME B89.1.6M, seems to have to do with ring gages. Is this what you're trying to calibrate?
 

AndyN

Moved On
I'm amazed that this is reported as an "ineffective" cal system! Was there a problem with parts being accepted by gauges calibrated on the Vision system?

At best it might warrant a comment in the report about the need to check into what's acceptable, but "ineffective", seriously? This auditor has some kind of bias about this stuff?
 
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