Oh no. There's two of them. 
C'mon people,splitting hairs like this accomplishes nothing.
C'mon people,splitting hairs like this accomplishes nothing.
Ball size testing
- Thread starter jtompilot
- Start date
An error is an error is an error no matter how you want to split the hairs.Oh no. There's two of them.
Balls are made in millimeters and such…a gauge should be.
Well, the average hair is about 0.08mm in diameter. Gotta shave a little off 
Aramith's site lists the balls as being '57.2mm(2.25")'. Good enough me. You guys better alert Aramith to their gross negligence.An error is an error is an error no matter how you want to split the hairs.
Balls are made in millimeters and such…a gauge should be.
You just listed they list the balls in millimeters.Aramith's site lists the balls as being '57.2mm(2.25")'. Good enough me. You guys better alert Aramith to their gross negligence.
Both. https://www.aramith.com/regular-range-pool I don't live in Euroland so i go by 'Murican specs: 2.25". Just measured a set of 20yr old Cennt's. All were within spec. Most were still dead on.You just listed they list the balls in millimeters.
No. It doesn’t matter what units the machine that made them is. It matters what the specification is from the people that set them. That is NOT the manufacturer.An error is an error is an error no matter how you want to split the hairs.
Balls are made in millimeters and such…a gauge should be.
Hell, most CNC machine tools today use metric ball screws to move each axis. Yet they can make an inch size screw, such as 5/16-14 used on our cues. You can bet the go no go gauge to measure that thread is in inches.
My left one is larger than my right one After testing. What’s a guy to do?
Sample set is in process, and scheduled to ship to me Jan 28.
Wouldn't 3D printing not also be an option or is that relatively expensive??
An error is an error is an error no matter how you want to split the hairs.
Balls are made in millimeters and such…a gauge should be.
57.20mm is 2.25197 inches. So the difference between 57.20mm and 2.250 inches is around 2 thousandths of an inch, which is probably less than the manufacturing error on the laser or milling CNCs that would be used here. Meaning that cheap machines aren't going to be able to repeatedly cut (mill, bore) a hole that is 2.25297 inches in diameter. And I would bet Aramith's own equipment isn't capable of that precision to make the balls because it's not required by the WPA.
Edit:. I'm wrong here, looks like the laser vendor here can do .001 accuracy.
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Cheap 3D printers would struggle to hit the +/- 0.005" required by the spec Bob posted.
And some may be interested that the inch is legally defined in terms of millimeters. Specifically, the definition of an inch is 25.4 mm, exactly. Further, the WPA/BCA/entire world specs for pool balls are given in inches as 2 1/4 (plus minus a tolerance). 2.25 inches is exactly equivalent to 1143/20 mm which in decimals is 57.15 mm, exactly. 57.15mm is the companion WPA spec. 2.25 inches and 57.15 mm are exactly the same length/diameter.
If Aramith said 57.2, they may have just been rounding. You could ask them.
(And the meter, along with millimeters, is defined in terms of the speed of light in a vacuum. A meter is the distance that light travels in 1/299,792,458 seconds, exactly. And the second is defined as the time that cesium atoms take to make 9,192,631,770 cycles of a certain mode of oscillation, exactly. I know this stuff partly because I used to work on equipment that was over a billion times more precise than those numbers. Yes, that's a lot of zeroes.)
Guys, if someone says 57.2mm on a marketing website, that does not mean the engineers, machinists, quality control people, etc, are working to that number. Its just a marketing number. The way pool balls are made are the same as steel ball bearings. The tolerances are super tight. The machines that make these would have knobs and readouts that go to .0001" increment, or .002mm increment (and even smaller increments! These are the largest those increments would be for grinding machines). Those are the "standard" increments for grinding machines, if it has inch screws or mm screws. That's how they will dial in their grinding machines. Now, there will be some variation of what gets spit out of those machines, of course. What they do next is sort the balls. Hell, maybe they even have gauges like the ones in this thread to do that sorting quickly. The best sets will get the balls closest to the nominal size (2.2500"), and the nominal weight. The balls with the wider tolerances will go in the lesser sets. And the ones really bad will go inside the magnetic cueballs.
Metal ball bearings go through this same sorting process. The ones that came off the machine closest to the nominal size will make it to the highest grade ball bearings. Etc.
Metal ball bearings go through this same sorting process. The ones that came off the machine closest to the nominal size will make it to the highest grade ball bearings. Etc.
Resistors used in electrical circuits used to have a similar sorting process. To get 1%-accurate resistors, the manufacturer would do the best they could and then select the ones that were within 1% and sell the others as 5%. This meant that usually a 5% resistor would never be within 1%. It was guaranteed to be at least 1% off.
CrankyThunder
Member
I have been following this thread and got amused when we started converting from the english to metric system.
I am surprised that nobody has considered the thermal expansion and contraction of the billiard balls and the gauge with temperature fluctuations. As the temperature rises, the billiard ball will expand while the hole in the gauge will probably contract, even if the gauge was manufactured from the same material as the billiard ball.
Since you guys are splitting hairs with such precision, you gotta factor in thermal expansion!
Grab the Popcorn Guys!
I am surprised that nobody has considered the thermal expansion and contraction of the billiard balls and the gauge with temperature fluctuations. As the temperature rises, the billiard ball will expand while the hole in the gauge will probably contract, even if the gauge was manufactured from the same material as the billiard ball.
Since you guys are splitting hairs with such precision, you gotta factor in thermal expansion!
Grab the Popcorn Guys!
The hole will expand in the gauge when the temperature increases.I have been following this thread and got amused when we started converting from the english to metric system.
I am surprised that nobody has considered the thermal expansion and contraction of the billiard balls and the gauge with temperature fluctuations. As the temperature rises, the billiard ball will expand while the hole in the gauge will probably contract, even if the gauge was manufactured from the same material as the billiard ball.
Since you guys are splitting hairs with such precision, you gotta factor in thermal expansion!
Grab the Popcorn Guys!
For cold balls shrinking, see this thread I did a while back:
Pool balls shrink in the cold, too;) (Precise data included)
I decided to see how much ball temperature affects ball diameter. I put an Aramith made Rempe cue ball in the freezer for one full day, took it out, and measured its diameter and temperature. I did this every few minutes until the ball reached room temperature and its diameter stabilized. The...
forums.azbilliards.com
A dimension unit is irrelevant to the dimension, it's just a way to measure and record the dimension. You just to understand precision and error. BTW I figure my Centennial balls are close to 3.08585e-5 nautical miles in diameter.An error is an error is an error no matter how you want to split the hairs.
Balls are made in millimeters and such…a gauge should be.
Dave <-- has many rules and vernier calipers that have both mm and inch scales ... and is now wondering which one of those is wrong/not-to-be-used