Thanks Stan but I can't fully agree with your comment. It's true that any tube (or pipe) whether it be a Damascus gun barrel or modern made product contains eccentricity. It's unavoidable even with the best process technology has to offer. Locating and quantifying eccentricity can be problematic regardless of the method used but, this method can detect eccentricity. Let's take a look at this drawing and crunch some numbers:
Measuring and comparing the ID, OD and calculated wall thickness of the three points will reveal eccentricity. For example:
It's easy to see there is considerable difference in wall thickness between points A & B and B & C but only 0.002" difference between points A & C. One can safely assume the barrel contains eccentricity. The only downfall is trying to determine which side of the barrel has the eccentricity. We know it lies at point B but is at the top or bottom side of the barrel or both? Does it really matter?
In the extreme, if the location of the eccentricity must be known then
this gage can be used to better understand the nature of the eccentricity.
If one has the means and can justify the cost then this high tech
ultrasonic gage from Olympus is the way to go for finding the true wall thickness of any tube or gun barrel. But, since I'm a real cheapskate, I'll keep working with this el cheapo bore gage to figure out its limitations and full capability. Hey, it works for me!
Hank
