Just for fun, How round is a billiard ball?

BC21 said:
The +/- 0.001" is for roundness. The surface smoothness of a pool ball is closer to +/- 0.001mm.
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Not to be a nit picker, but "surface roughness" is the common way to refer to this property ... although it turns out a google search for "surface smoothness tester" comes up with no end or roughness testers :D

Dave <-- made his spherometer in advance of grinding a few lenses & mirrors, which will be a retirement adventure into both curvature and smoothness/polish
 
DaveK said:
Interesting. I tested my Centennial 1 ball and 15 ball, and found a maximum deviation of about 0.0015", certainly <0.002". The worst place was over the numbers and stripe as you noted .... on the other parts of the ball (1 ball in particular) the deviation was under a thou.

And my antique spherometer was useless for testing 2.25" balls, but may have had enough range to test Russian Billiards or perhaps bowling balls :)

Dave
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I bought a spherical micrometer at the ’89 trade show….they said they’d ship to me when they got home home….….
….never came….I waited til the next trade show…they had no record.
I had paid for it by credit card…so I could’ve proven it…but, to me, it wasn’t worth the hassle.
 
pt109 said:
I bought a spherical micrometer at the ’89 trade show….they said they’d ship to me when they got home home….….
….never came….I waited til the next trade show…they had no record.
I had paid for it by credit card…so I could’ve proven it…but, to me, it wasn’t worth the hassle.
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Hope you aren't out much. From what I know a "spherical micrometer" would be useless for measuring spheres.


I have a couple, a Starrett 220


and a Starrett 569


And no, I did not pay anywhere near those prices !

Dave
 
DaveK said:
Not to be a nit picker, but "surface roughness" is the common way to refer to this property ... although it turns out a google search for "surface smoothness tester" comes up with no end or roughness testers :D

Dave <-- made his spherometer in advance of grinding a few lenses & mirrors, which will be a retirement adventure into both curvature and smoothness/polish
Click to expand...
Profilometer is the tool for that job,
 
Renegade_56 said:
Profilometer is the tool for that job,
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Interesting. I've always referred to them as roughness testers ... like these : https://www.grainger.com/category/m...ce-property-testing/surface-roughness-testers

But I see that there are differences, likely not relevant to the vast majority of pool players but of course there are nerds like me :)

Understanding Surface Profile

www.elcometer.com www.elcometer.com

What is the difference between a roughness meter and a profiler

What is the difference between a roughness meter and a profiler
www.kairda-group.com www.kairda-group.com
^^^seems to indicate that we are discussing "roughness" as opposed to "profile"

Dave
 
DaveK said:
Interesting. I've always referred to them as roughness testers ... like these : https://www.grainger.com/category/m...ce-property-testing/surface-roughness-testers

But I see that there are differences, likely not relevant to the vast majority of pool players but of course there are nerds like me :)

Understanding Surface Profile

www.elcometer.com www.elcometer.com

What is the difference between a roughness meter and a profiler

What is the difference between a roughness meter and a profiler
www.kairda-group.com www.kairda-group.com
^^^seems to indicate that we are discussing "roughness" as opposed to "profile"

Dave
Click to expand...
Or maybe Renegade_56 was referring to profiling lenses and mirrors ... I can see how a profiler would be useful.

Dave
 
Would the measurements be more precise measuring light reflections/refraction patterns? Instead of using fancy calipers can the roundness be measured by bouncing lights at specific wavelengths off it.
 
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