GBeaman
Hot Rolled
- Joined
- Jun 13, 2006
- Location
- Marble Falls, TX
I don't want to drag this on too far, but there is a lot of info here.
I have a brand new ring gauge from MSC. The rep just personally dropped it off here at my shop. I am cutting a male fitting with a 7/8-20 2b thread on the OD.
I am using Vardex 3/8 IC External full profile 20UN threading inserts on my Mori Seiki SL-2 Turn center. So I thread the normal way, start a little off the major diameter, thread and check that the thread has not been topped, then measure with thread mics. I double checked my anvils on the thread mics and they are in the 14-24tpi anvils. Thread to pitch diameter minus 2 thou. Now the thread has been topped. Should by all measures be in size. The ring gauge will not go. Take some more... starts but is tight. Finally hit the bottom of the tolerance .8368 PD my mics show around .8365 and finally the gauge will go!
Sounds exactly like the behavior of a properly sized no go gauge. But the gauge is clearly laser marked from the factory and says "go" PD .8412. Is it possible that MSC has issued an improperly labeled gauge? Should it be a no go that is labeled go? I don't have a way of measuring the ID PD of the gauge. I have a 2b male thread plug gauge. But even the go shouldn't go into the ring gage, and it doesn't. I could double check on a bolt if there was such a thing commercially made. Any ideas? The gauge says "GF" gage on it I believe it is made in China. I don't know how to qualify my parts. I have always used the gauge as bible. If I had a thou or so discrepancy between the gauge and thread mics I would ignore it and use the gauge. But this the whole tolerance of the thread!
The pitch looks good. The pitch meshes very well with the male plug gauge, and 20 pitch is just .050 so I don't see that being the problem. It would act differently if it was pitch too!
Thanks in advance.
-Greg
I have a brand new ring gauge from MSC. The rep just personally dropped it off here at my shop. I am cutting a male fitting with a 7/8-20 2b thread on the OD.
I am using Vardex 3/8 IC External full profile 20UN threading inserts on my Mori Seiki SL-2 Turn center. So I thread the normal way, start a little off the major diameter, thread and check that the thread has not been topped, then measure with thread mics. I double checked my anvils on the thread mics and they are in the 14-24tpi anvils. Thread to pitch diameter minus 2 thou. Now the thread has been topped. Should by all measures be in size. The ring gauge will not go. Take some more... starts but is tight. Finally hit the bottom of the tolerance .8368 PD my mics show around .8365 and finally the gauge will go!
Sounds exactly like the behavior of a properly sized no go gauge. But the gauge is clearly laser marked from the factory and says "go" PD .8412. Is it possible that MSC has issued an improperly labeled gauge? Should it be a no go that is labeled go? I don't have a way of measuring the ID PD of the gauge. I have a 2b male thread plug gauge. But even the go shouldn't go into the ring gage, and it doesn't. I could double check on a bolt if there was such a thing commercially made. Any ideas? The gauge says "GF" gage on it I believe it is made in China. I don't know how to qualify my parts. I have always used the gauge as bible. If I had a thou or so discrepancy between the gauge and thread mics I would ignore it and use the gauge. But this the whole tolerance of the thread!
The pitch looks good. The pitch meshes very well with the male plug gauge, and 20 pitch is just .050 so I don't see that being the problem. It would act differently if it was pitch too!
Thanks in advance.
-Greg