Hey everybody,
I keep getting different answers to this question. I need to order GO/NO GO plug gages for a .4982 +/- .0005 hole. So some engineers believe I need to order undersize (.4975) for the "GO" pin to avoid the size on size issue or some call it a slip fit.
This is what it calls for on the print, .4982 bore +/-.0005 but the control plan calls for the "Go" Pin on the plug gage to be .4975 (allowing .0002 for the size on size issue) and .4987 for the NO GO pin.

My quandry is that other engineers have said that I should order exactly what the tolerance is on the print (.4982 +/- .0005) so therefore I would order .4977/.4987 right?

Please weigh in on this issue if you have a spare minute.

Thanks a bunch,
Gagelady:frust:

Hey everybody,
I keep getting different answers to this question. I need to order GO/NO GO plug gages for a .4982 +/- .0005 hole. So some engineers believe I need to order undersize (.4975) for the "GO" pin to avoid the size on size issue or some call it a slip fit.
This is what it calls for on the print, .4982 bore +/-.0005 but the control plan calls for the "Go" Pin on the plug gage to be .4975 (allowing .0002 for the size on size issue) and .4987 for the NO GO pin.

My quandry is that other engineers have said that I should order exactly what the tolerance is on the print (.4982 +/- .0005) so therefore I would order .4977/.4987 right?

Please weigh in on this issue if you have a spare minute.

Thanks a bunch,
Gagelady:frust:

Gagelady,

I did a quick search, and found this (http://www.engineersedge.com/wwwboard/posts/2363.html) on the Engineers Edge site (sorry Marc).

Stijloor.

Try also this previous thread on the same topic

Allowance for Slip Fit - Additional Allowance applied to GO NO GO Plug Gag (http://Elsmar.com/Forums/showthread.php?t=26337&referrerid=5457)

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 Go/NoGo pin gauges the Go member would have a + tolerance and the NoGo member would have a - tolerance.

For Go/NoGo ring gauges the Go member would have a - tolerance and the NoGo member would have a + tolerance. (in this case the go member is the largest diameter acceptable)

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.

Hey everybody,
I keep getting different answers to this question. I need to order GO/NO GO plug gages for a .4982 +/- .0005 hole. So some engineers believe I need to order undersize (.4975) for the "GO" pin to avoid the size on size issue or some call it a slip fit.
This is what it calls for on the print, .4982 bore +/-.0005 but the control plan calls for the "Go" Pin on the plug gage to be .4975 (allowing .0002 for the size on size issue) and .4987 for the NO GO pin.

My quandry is that other engineers have said that I should order exactly what the tolerance is on the print (.4982 +/- .0005) so therefore I would order .4977/.4987 right?

Please weigh in on this issue if you have a spare minute.

Thanks a bunch,
Gagelady:frust:


You are specifying ±.0005", is the pin gauge the best method for checking this specification? Are they any other gauging methods available to at your facility?

Phil