Ball size testing

[DaveK]

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!

lol ... the standards for my micrometers are spec'd at 20* C .... I use them when it's only 19* sometimes ... call me crazy !

Dave

 

[stevelomako]

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.

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

There’s a reason manufacturers use a certain measurement. You use the one that they do.

Your tools have both measurements for…wait…wait…….convenience.

 

[DaveK]

There’s a reason manufacturers use a certain measurement. You use the one that they do.

Your tools have both measurements for…wait…wait…….convenience.

No, not for convenience, because it doesn't really matter what units you use ... that's why we have constants, to account for whatever units you pick (the pick is arbitrary but certainly chosen for convenience of the picker ... of course this does not explain why the USA keeps non-metric units in many situations ... never mind).

Dave

 

[stevelomako]

No, not for convenience, because it doesn't really matter what units you use ... that's why we have constants, to account for whatever units you pick (the pick is arbitrary but certainly chosen for convenience of the picker ... of course this does not explain why the USA keeps non-metric units in many situations ... never mind).

Dave

I tried to find a spherometer for you in SAE but no luck.

Hmm

 

[DaveK]

I tried to find a spherometer for you in SAE but no luck.

Hmm

lol ... SAE is the Society of Automotive Engineers, they have no involvement with the standardization of length/area/volume units. But I will use SAE standardized threads on my spherometer ... made on my Myford ML7 that is built with BS* threads.

I am making one in Imperial units, no worries there ... and I know how to convert units, no worries there either.

Dave

 

[stevelomako]

lol ... SAE is the Society of Automotive Engineers, they have no involvement with the standardization of length/area/volume units. But I will use SAE standardized threads on my spherometer ... made on my Myford ML7 that is built with BS* threads.

I am making one in Imperial units, no worries there ... and I know how to convert units, no worries there either.

Dave

SAE-Standard American English, Imperial units of measurement.

You’re welcome

 

[stevelomako]

Oops, I forgot…

 

[DaveK]

SAE-Standard American English, Imperial units of measurement.

You’re welcome

Guess I see SAE a bit differently, and consider NIST to be the ones who define units of length measure. When you get a length standard they often claim calibration traceability to NIST, not SAE.

Dave

 

[stevelomako]

Guess I see SAE a bit differently, and consider NIST to be the ones who define units of length measure. When you get a length standard they often claim calibration traceability to NIST, not SAE.

Dave

Go get you an SAE or Metric wrench

 

[Renegade_56]

over 100 responses and no one has mentioned that a round hole in a plate, even if it were perfectly round, cannot measure how accurately a sphere is made, best it can do is give an idea of whether the mean diameter on a given plane will fit thru the hole. That is not roundness. You could pass a ball thru the hole, rotate the ball randomly in your hand, and then try to pass it thru the same hole and it may or may not pass through. Very precision shafts are generally measured in industry with 3 point indicator micrometers which can show variations in size of a shaft that a 2 point micrometer cannot. Just because the measurements with 2 point pics are the same does not make the shaft (or a sphere) round necessarily.

 

[Poolplaya9]

over 100 responses and no one has mentioned that a round hole in a plate, even if it were perfectly round, cannot measure how accurately a sphere is made, best it can do is give an idea of whether the mean diameter on a given plane will fit thru the hole. That is not roundness.

The main participants in the this thread are well aware of that, but this thread is about ball size, not roundness, and the gauges and methods mentioned in this thread do a good enough job of determining ball size to a sufficient degree of accuracy for the practical purposes that were in mind. And while he was talking about gauges rather than balls (spheres) at the time, in post #5 Bob Jewett did allude to the same general principles you have in mind.

Ball size testing

I’m tired of all the screwed up balls not racking properly so I bought a test gage and tested a set of Aramith Tournament balls. The six ball fell through the smallest hole, didn’t really come close to touching the template. Three balls wouldn’t...

forums.azbilliards.com

For those that are interested in a higher degree of precision than was warranted for most people for the practical purposes that were in mind here, and in the ball roundness in particular, there is a separate thread specifically addressing roundness which sounds like would be of interest to you.

Designing and building ball roundness tester

I'm working on a ball sphericity (roundness) tester for fun. Below are a couple of pictures, and a YouTube video link describing the process. I'll update as I go. My motivation is to see how different ball sets and brands compare both when new...

forums.azbilliards.com

 

[Fatboy]

There’s a reason manufacturers use a certain measurement. You use the one that they do.

Your tools have both measurements for…wait…wait…….convenience.

I just lie and add 4” in conversation

 

[DaveK]

Go get you an SAE or Metric wrench

BA

Dave

 

[DaveK]

I have only one BA wrench, keep it as a curiosity as I have no real use for it.

Funny story, I recently bought a Myford ML7 lathe. It uses Whitworth fasteners (55* V not SAE & metric 60* V). When I disassembled a few parts to move and clean it my wrenches did not fit . Ended up filing down the flats to fit. The first bolt heads were filed a bit so my 7/16" wrench worked, so far so good. The next couple of nuts were a little too big for my 1/2" wrenches so I started filing. After maybe 8 or 10 strokes the nut was still too large, so I measured it ... with a dual-scale Vernier caliper. Reading the measurement I realized that it could be filed down to 13mm quicker than filing it down to 1/2". Now I have a few metric nuts in my english lathe. Good times !

BTW I disassembled the lathe with an adjustable wrench, a (real) Crescent wrench an old King Dick adjustable spanner I have for these situations

Dave <-- in Canada with a toolbox full of SAE and metric wrenches and sockets and taps and dies ... and of course that one BA wrench

 

[iusedtoberich]

Update, I received the parts today. They look pretty good. The laser start and stop did not coincide with the area I wanted it to, so I'll have to carefully remove its "nub". I will take the samples home today, measure them, and try them on some balls. Picture to follow in next post.

 

[iusedtoberich]

Sorry the pictures are rotated I can't figure it out. Anwyay, there is brass, aluminum (2 thicknessses), steel (2 thicknesses), stainless steel. And multiple sizes to test the accuracy. The etching shows up better in some materials than others. I also tried different size etching. I'd have to touch up the edges to remove any burrs, and possibly go over the whole surface with a scotchbrite pad.

 

[kling&allen]

Update, I received the parts today. They look pretty good. The laser start and stop did not coincide with the area I wanted it to, so I'll have to carefully remove its "nub". I will take the samples home today, measure them, and try them on some balls. Picture to follow in next post.

I'll be interested to see how these laser cut pieces do with your steel reference bearing.

 

[iusedtoberich]

I'll be interested to see how these laser cut pieces do with your steel reference bearing.

I’ve made a lot of progress for that too. Short story is the steel bearing is within .0001” TIR across its entire surface. A used Aramith Super Pro striped ball varies about .0015” TIR. I will update that thread soon.

 

[kling&allen]

I’ve made a lot of progress for that too. Short story is the steel bearing is within .0001” TIR across its entire surface. A used Aramith Super Pro striped ball varies about .0015” TIR. I will update that thread soon.

Any updates on this ball size tester made from laser cut metal?

 

[iusedtoberich]

Any updates on this ball size tester made from laser cut metal?

I haven’t touched it in a few months. They needed some hand filing to remove the “nub” left behind at the laser entrance. I also don’t have a good way to verify their diameter. I was thinking to turn a gauge to size to verify. I can’t directly measure it with anything other than the inside jaws of a dial caliper. Not good enough for this job imo.