juan_mexia
Registered
Hi,
Can someone share a procedure to use ring gages to verify external threads? The thread I am trying to measure is an NPT thread and the specification on the print says:
"INSPECT USING STD LPI NPT RING GAGE. THREADS MUST ACCEPT 3-1/2 TURNS WITH A TOLERANCE OF 1-1/2 TURN"
The problem is that I am measuring the threads and I am rejecting the parts because, according to my inspection method, they are bigger than the specification. My supplier is reviewing the parts and they find them within specification but their method is different than mine.
I will try to explain both methods:
My inspection method
1) Hand tighten the gauge without applying too much force until the gauge does not accept any more turns
2) Put a mark on the gauge where the threads start
3) If the edge of the gauge is above the edge of the part, count how many turns would be needed to insert the gauge until is flush with the part. The count of turns would be your results but in negative number (eg. -2 turns)
4) If the edge of the gauge is below the edge of the part, count how many turns the edge of the gauge passes the edge of the part. The count for turns would be your results in positive number (eg. +2 turns)
Supplier inspection method
1) Hand tighten the gauge without applying too much force until the gauge does not accept any more turns
2) The inspector counts how many turns it takes to disengage the ring gage from the part.
With the supplier inspection method there would not be any negative results
I hope you can guide me on what is the proper method to inspect these threads
Can someone share a procedure to use ring gages to verify external threads? The thread I am trying to measure is an NPT thread and the specification on the print says:
"INSPECT USING STD LPI NPT RING GAGE. THREADS MUST ACCEPT 3-1/2 TURNS WITH A TOLERANCE OF 1-1/2 TURN"
The problem is that I am measuring the threads and I am rejecting the parts because, according to my inspection method, they are bigger than the specification. My supplier is reviewing the parts and they find them within specification but their method is different than mine.
I will try to explain both methods:
My inspection method
1) Hand tighten the gauge without applying too much force until the gauge does not accept any more turns
2) Put a mark on the gauge where the threads start
3) If the edge of the gauge is above the edge of the part, count how many turns would be needed to insert the gauge until is flush with the part. The count of turns would be your results but in negative number (eg. -2 turns)
4) If the edge of the gauge is below the edge of the part, count how many turns the edge of the gauge passes the edge of the part. The count for turns would be your results in positive number (eg. +2 turns)
Supplier inspection method
1) Hand tighten the gauge without applying too much force until the gauge does not accept any more turns
2) The inspector counts how many turns it takes to disengage the ring gage from the part.
With the supplier inspection method there would not be any negative results
I hope you can guide me on what is the proper method to inspect these threads