We are running a part with a 3" cylinder. The cylinder has a .0002 cylindricity call out. For 10 years we have been using a air Gage to measure this feature, we zero the Gage & spin it throughout the cylinder & the total reading is what we use as our result. Anyway, I was asked to start measuring this on our CMM, I get the cylindricity reading at around .001 every time, I measured a master ring the nominal size of this cylinder & also get the cylindricity around .001. Can I hear everyone's input on measuring cylindricity please.
1.) Which way is more accurate, CMM or air gage (I have tried multiple sized probes & stylus lengths.
2.) Is cylindricity of a cylinder the same as roundness of a circle??
Depending on what kind of touch trigger probe you use, the results can be better or worse. A Renishaw TP200 has a virtually non existent roundness error, whereas a TP20 and comparable probe systems produce a three-lobed error pattern when measuring a perfect round gage. A TP20 in a PH20 however gives better results due to the rotation of the head during probing.
Best choice for form measurements is always a scanning system.
The air gage has physical limits when it comes to form measurement.
Depending on what kind of touch trigger probe you use, the results can be better or worse. A Renishaw TP200 has a virtually non existent roundness error, whereas a TP20 and comparable probe systems produce a three-lobed error pattern when measuring a perfect round gage. A TP20 in a PH20 however gives better results due to the rotation of the head during probing.
Best choice for form measurements is always a scanning system.
The air gage has physical limits when it comes to form measurement.