5/16-18 thread angle.

M

Mensabum

Well-known member
Hello guys.
Are there differences in the thread angle of 5/16-18 pins on some cues??
I'm having trouble getting shafts to screw on to what is supposed to be the size mentioned above. Meucci shafts won't fit a Heubler, Players shaft fits Mali, but not Meucci, etc...
These are all 5/16-18 cues. What's up fellas??
Can anybody chime in here and gimme the deets??
 
cueman said:
The thread angle on all mentioned is 60 degree. But the outside diameter varies. Thus Huebler shaft goes on Meucci, but Meucci does not go on Huebler.
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Ok. Can you elaborate for me as I'm not familiar with how the diameter of a 5/16" pin can vary.
Must be in the thousandths, I imagine. But just enuf to cause issues.
Is that a proprietary thing??
 
Mensabum said:
Does the variance lie in the male or female part of the joint?? Pin or receiver??
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The thread form like all machined parts has an tolerance. The Major Diameter is what Cueman is talking about.
The chart in this link shows Dimensions for a Class of Fit 2A & 3A. Basically this is how much engagement between male and female parts, or lets say how close of a fit a machinist wants between parts. Remember there has to be some clearance or you'll play heck trying to get them together.

ANSI External Screw Threads Size Tolerances Chart

ANSI/ ASME EXTERNAL Screw Thread Size Chart. All units are in inches. Unified Screw Threads per. ANSI/ASME B1.1-1989 (R2001), R2001) Nomenclature, are used. Acceptability criteria are described in ANSI/ASME B1.3M-1992 (R2001).
www.engineersedge.com
 
3kushn said:
The thread form like all machined parts has an tolerance. The Major Diameter is what Cueman is talking about.
The chart in this link shows Dimensions for a Class of Fit 2A & 3A. Basically this is how much engagement between male and female parts, or lets say how close of a fit a machinist wants between parts. Remember there has to be some clearance or you'll play heck trying to get them together.

ANSI External Screw Threads Size Tolerances Chart

ANSI/ ASME EXTERNAL Screw Thread Size Chart. All units are in inches. Unified Screw Threads per. ANSI/ASME B1.1-1989 (R2001), R2001) Nomenclature, are used. Acceptability criteria are described in ANSI/ASME B1.3M-1992 (R2001).
www.engineersedge.com
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Appreciate that!!
I was also told by PM there's a difference on some of the pins used. Acme makes a 5/16-18, but the acme thread has a broader thread root than Standard threads do. Standard threads have square roots whereas Acme has an angled root that flares out at the thread base. Good luck getting that to screw onto your Meucci!!
Standard threads also come in coarse, fine and extra fine sizes, making this even more screwy than I ever thot it could be. Pardon the pun. Lol.
Then there's thread angle!! 🤯
All these differences amount to why some 5/16-18's match up and others don't.
I believe the 'Stroud Meister' was the first cuemaker to use the then new Acme pins on his JW cues. Correct me if I'm wrong.
Thanks to everyone who helped me figure this mess out. Ask and ye shall receive. Lol.
 
Mensabum said:
Appreciate that!!
I was also told by PM there's a difference on some of the pins used. Acme makes a 5/16-18, but the acme thread has a broader thread root than Standard threads do. Standard threads have square roots whereas Acme has an angled root that flares out at the thread base. Good luck getting that to screw onto your Meucci!!
Standard threads also come in coarse, fine and extra fine sizes, making this even more screwy than I ever thot it could be. Pardon the pun. Lol.
Then there's thread angle!! 🤯
All these differences amount to why some 5/16-18's match up and others don't.
I believe the 'Stroud Meister' was the first cuemaker to use the then new Acme pins on his JW cues. Correct me if I'm wrong.
Thanks to everyone who helped me figure this mess out. Ask and ye shall receive. Lol.
Click to expand...

There is a lot more to an acme thread than a wider root. It's a trapezoidal thread profile.

'standard' threads are simply 60degree v-profile threads and can be made to any pitch and diameter one wishes. American Standard threads generally come in fractional sizes with the three designations you mention (coarse, fine, ef). Metric screws are measured a bit differently, but usually come in standard or fine designations, though in 13yrs at a world leader of automation equipment, about 99.9% of our screws were standard metric with the exceptions mostly being very large screws for mounting equipment.
 
Mensabum said:
Ok. Can you elaborate for me as I'm not familiar with how the diameter of a 5/16" pin can vary.
Must be in the thousandths, I imagine. But just enuf to cause issues.
Is that a proprietary thing??
Click to expand...
Common 5/16-18 outside diameter is .310" only two thousandths undersized to true 5/16. But Meucci is often closer to .300" and .304' or so its very common also. Also sometimes the threads are not rolled as deep which makes them fit tighter. Some use a 17-64 (.266") hole in the insert before tapping or threading and others use an F drill (.256") and others use a 1/4 (.250"). So yes thousandths matter and the combination of factors matter. The .300" john screw will go in any of the above tapped inserts, but only the .300" pin will go in the insert tapped into the .250 hole. I wont even go into H factor taps since most use CNC lathes to cut threads now instead of tapping brass parts. But they still use factors to decide how tight the fit is.
 
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DeeDeeCues said:
There is a lot more to an acme thread than a wider root. It's a trapezoidal thread profile.

'standard' threads are simply 60degree v-profile threads and can be made to any pitch and diameter one wishes. American Standard threads generally come in fractional sizes with the three designations you mention (coarse, fine, ef). Metric screws are measured a bit differently, but usually come in standard or fine designations, though in 13yrs at a world leader of automation equipment, about 99.9% of our screws were standard metric with the exceptions mostly being very large screws for mounting equipment.
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Thanks. This is why I asked this question in both forums. I figured the technical data might not be as digestible on the main forum as it is here. I hope it wasn't a mistake. If so, apologies.
 
Mensabum said:
Thanks. This is why I asked this question in both forums. I figured the technical data might not be as digestible on the main forum as it is here. I hope it wasn't a mistake. If so, apologies.
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You're welcome. Anyone who gets too twisted up about a question asked in both forums should probably take a few minutes and assess how seriously they take the forums.

I've seen a lot of pin-and-thread discussions, and I think there is a lot of great information this time around. A lot more facts and a lot less arguing about opinions.
 
DeeDeeCues said:
You're welcome. Anyone who gets too twisted up about a question asked in both forums should probably take a few minutes and assess how seriously they take the forums.

I've seen a lot of pin-and-thread discussions, and I think there is a lot of great information this time around. A lot more facts and a lot less arguing about opinions.
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I second the motion!!!👍🏻
 
I had a 5/16x14 pin cue that would not screw down all the way on aftermarket shaft. Thought it was the pilot stopping it. Turns out I had to shave the first thread of the pin down a little so I could screw it all the way down. I had 4 other 5/16x14 butts that fit with no problems.
 
chuckpilegis said:
I had a 5/16x14 pin cue that would not screw down all the way on aftermarket shaft. Thought it was the pilot stopping it. Turns out I had to shave the first thread of the pin down a little so I could screw it all the way down. I had 4 other 5/16x14 butts that fit with no problems.
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Not all joint screws are set at the same length and not all brass inserts are thru inserts.
 
Michael Webb said:
Not all joint screws are set at the same length and not all brass inserts are thru inserts.
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One of the reasons I started this post was I received a number of old growth shafts at 5/16-18 that I wanted to play on different butts. Knowledge of all the minutia required was making me crazy, as they fit on some, but not others. I feel for any cuemaker doing repairs today. Never know what you're going to run across. Perhaps this is naive but wouldn't standardization of these sizes makes things simpler and easier on all involved??
 
Mensabum said:
One of the reasons I started this post was I received a number of old growth shafts at 5/16-18 that I wanted to play on different butts. Knowledge of all the minutia required was making me crazy, as they fit on some, but not others. I feel for any cuemaker doing repairs today. Never know what you're going to run across. Perhaps this is naive but wouldn't standardization of these sizes makes things simpler and easier on all involved??
Click to expand...
Good luck with that.
 
The conventional wisdom concerning screw threads, it is the pitch diameter that dictates the fit. Major and minor diameters are a clearance fit. In the cue industry they will sometimes use these sizes as a way of creating the alignment between the shaft and butt. This is the norm in most of the 3/8 modified pins. In the 5/16 size pins they usually use a secondary diameter or pilot diameter to form the alignment. The moral of the story is the cue industry uses a variety of proprietary threads and doesn't conform conventional engineering standards. When I set out to design my pins for my cues I wanted them to be able to be reproduced with conventional tooling. So any cue maker could build a shaft for one of my cues. So I opted for a 3/8 by 10 modified. The OD of the pin is 3/8 nominal, The ID of the insert is 19/64 that can be reproduced with a reamer and the threads can be made with a conventional 3/8 by 10 tap. So in other words you can build a shaft for my cues and thread the insert with a drill, reamer and tap. I opt to use live tooling to create my diameters only for the sake of having a cleaner finish. I have had to reverse engineer many parts in my day job and have a great appreciation for manufactures who build parts to nominal standards instead of bastard sizes.
 
Mensabum said:
One of the reasons I started this post was I received a number of old growth shafts at 5/16-18 that I wanted to play on different butts. Knowledge of all the minutia required was making me crazy, as they fit on some, but not others. I feel for any cuemaker doing repairs today. Never know what you're going to run across. Perhaps this is naive but wouldn't standardization of these sizes makes things simpler and easier on all involved??
Click to expand...
Making things not easy to interchange was part of the reason some made things odd. They want you to buy their product for their cues not another brand product for their cue.
 
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