Can someone tell me where I can find, in writing, what the industry standard is for attribute gage tolerances. I have always used the following : When checking a 0.150" ±0.003" hole diameter, I would use a 0.153 minus pin for the Nogo and a 0.147" plus pin for the Go OR if I was checking a 0.150" ±0.003" shaft I would use a 0.153" minus ring for the Go and a 0.147" plus ring for the Nogo. I am having a "discussion" with Engineering and they said that I am incorrect because I would be failing good product. I tried to explain to them that we would want to error for the customer and if the gage did not fit the hole, then we would verify the dimension by using a measurement instrument such as a comparator or CMM. Without written published documentation, my 15 years experience is not worth much.

Can someone tell me where I can find, in writing, what the industry standard is for attribute gage tolerances. I have always used the following : When checking a 0.150" ±0.003" hole diameter, I would use a 0.153 minus pin for the Nogo and a 0.147" plus pin for the Go OR if I was checking a 0.150" ±0.003" shaft I would use a 0.153" minus ring for the Go and a 0.147" plus ring for the Nogo. I am having a "discussion" with Engineering and they said that I am incorrect because I would be failing good product. I tried to explain to them that we would want to error for the customer and if the gage did not fit the hole, then we would verify the dimension by using a measurement instrument such as a comparator or CMM. Without written published documentation, my 15 years experience is not worth much.
I don't know of any such written standards. I think that what's being missed here is process control. If holes are the wrong size, it's almost always attributable to tool wear (drills or punches), and tools should be changed before nonconforming material is produced. I understand that you still have to measure the holes, but if you understand the process variation, there shouldn't be any need for arguments about pin sizes, imo.

Good point. You are correct that we should change tools before nonconforming material is produced. Process control is very important. However, the prefered inspection method at the moment at my facility is to use a Go/Nogo pin gage (Red and Green handle) to confirm the hole diameter is within print specifications. How would you specify what pin sizes and tolerance to use for the go/nogo gage that will be used to check an internal diameter?

Good point. You are correct that we should change tools before nonconforming material is produced. Process control is very important. However, the prefered inspection method at the moment at my facility is to use a Go/Nogo pin gage (Red and Green handle) to confirm the hole diameter is within print specifications. How would you specify what pin sizes and tolerance to use for the go/nogo gage that will be used to check an internal diameter?
I think the method you described in your original post is reasonable. What do the engineering people propose, especially in light of your (also reasonable) stipulation regarding rechecking with an alternate method if nonconforming material is discovered?

Check out the gaugemakers tolerance chart and/or the 10% rule. Basically you take 10% of your total product tolerance (.006") & see what class it fits into for your size range.

Check out mayagage.com for more info.

There is a standard:
ASME Y14.43-2003: Dimensioning and Tolerancing Principles for Gages and Fixtures



There are three gauging policies in use that I know of.
1. Accept most good parts, reject all bad parts (reject some borderline good parts). This policy is the ANSI preferred policy.

2. Accept all good parts, reject most bad parts (accept some borderline bad parts). Not an ANSI preferred policy.

3. Accept most good parts, reject most bad parts (reject some borderline good parts and accept some borderline bad parts). Not an ANSI preferred policy.


Number one is the ANSI preferred and standard policy in the U.S.



- Recommended gage tolerancing policy is that no bad parts will be accepted; therefore, a small percentage of borderline technically good (in tolerance) parts must be rejected

- ANSI standards recommend 5% of the part tolerance be used as gage tolerance, with an optional 5% for wear allowance. This is a total recommended 5-10% of the part tolerance to be used as gage tolerance.


For your Go/NoGo gauges the Go member would have a + tolerance and the NoGo member would have a - tolerance. The amount of acceptable product falsely rejected would depend upon the amount of tolerance allocated to the gauge and to how your process is centered.
Hope this is of some help.

Thank-you all for the information. I am in the process of ordering the standard ASME Y14.43-2003: Dimensioning and Tolerancing Principles for Gages and Fixtures. I have looked at the Gagemaker Tolerances in the Machinery's Handbook. The Machinery's Handbook also has an illustration showing in what directions to add the gage tolerances depending on if it is an outside or inside dimension. In either case, the tolerances are never outside of the print specifications.

There are three standards that you should read:
ASME B89.7.3.1 Guidelines for Decision Rules: Considering Measurement Uncertainty Determining Conformance to Specifications
ASME B89.1.5 Measurement of Plain External Diameters for use as Master Discs or Cylindrical Plug Gages
ASME B89.1.6 Measurement of Plain Internal Diameters for use as a Master Rings or Ring Gages
As far as I can tell from my contacts it is the internationally accepted norm to have the product tolerance be the gage limits. Circumstances such as costly gages, surface roughness, and cylindricity may require deviation from the norm. The ASME B89.7.3.1 paragraph 4.1 discusses the standard rule of thumb, the 10% tolerance rule. The rest of the standard gives you alternatives discussing guard bands and wear allowances. The gist of the standard is that you and your customer, or quality and engineering departments, review and agree on the gage tolerances, taking in consideration all aspects of the product fit and function.

To make your life just a little bit easier, there is a Gage Makers Tolerance Calculator on the web, which will calculate in both inch and metric options, at: http://www.ring-plug-thread-gages.com/ti-Gage-Makers-Tol-Calculator.htm

I have attached a PDF of the page showing the inch calculation. The page also has a brief description of the 10% tolerance rule.