wavy joint question

[Joe Barringer]

How I read their wording as a cuemaker is this. "The long alignment shoulder will help keep you from cross-threading the shaft on the joint pin."

I'll have to disagree with you Chris. As a cuemaker, I read it entirely different. A layman would read it as previously stated.

Seeing it as a cue maker, you first put the pin into the shaft. The "long alignment shoulder" plays absolutely no part in the initial alignment. The "long Shoulder" comes into play perhaps at the last 1/3 of tightening it up because that's when the "long shoulder' will first see the alignment hole. You have to get there first before it can "help".

 

[vasilios]

How I read their wording as a cuemaker is this. "The long alignment shoulder will help keep you from cross-threading the shaft on the joint pin."

I see it as a running start before the twist.a little built in idiotproofing, adding language of special engineering and if you buy, a smart choice was made.




bill

 

[Djay Customs]

I found already found somebody who's gonna make me a Tap!!
thanks for all the off topic things in my thread!!

 

[pdcue]

From a cue-performance standpoint, what, if any, are the reasons we should prefer a tight-fitting joint to one with lots of play or sloppiness as it is screwed together? Assume both types draw the butt and shaft joint faces together tightly, and they stay that way during use.

E-X-A-C-T-L-Y.

In a related note:
FWIW - the need for alignment "help" from the pin became unnecessary
sometime during the Kennedy administration.

Dale

 

[ronscuba]

.... There universally accepted standards for threads. When someone comes along with a new one that they claim is better without offering engineering proof, damn right I will bash them.

dld

I guess I drank the Mezz cool aid. Maybe it is the joint, or the tip, or the shaft, or the quality control, or tight tolerances or a combination of all those things. Whatever it is, this is a great playing cue.

 

[scdiveteam]

As far as your comment about the torque/force equations not being relevant, I'll assure you that they most certainly are relevant.

dld

Hey DD,

I do respect your comments and engineering background but I did not state or imply that torque force equations are irrelevant. On the contrary my point was that it is more sensitive in this specific application.

Also mechanical torque specifications standards for threading metals does not apply to threads cut in wood or phenolic insert materials with reference to possible thread degradation issues because of the delta that exists in the contrasting material strengths.

My point was that X amount of torque on a metal thread to an acceptable torquing standard for a 3/8" unit using a calibrated torque wrench could eventually have an adverse effect on any wood fibers of the internal thread that is loose fitting because the modulus of the wood material is significantly less (-X of the metal standard). Hence a loose fitting threaded interface is not the ideal one would look to achieve in a shaft.

Who cares if you can move the shaft sideways when it isn't tight?
dld

A snug fit on the minor with as much of a thread footprint on the inclined plane within the hole and more TPI is a desired thing because the total loading is distributed over more surface area, IMO and fiber inserts are better than wood for this application. With metal to wood, if the joint loosens up a hair during play and you hit a ball, the load is transferred to the threads only which can degrade the wood fiber pronto. With a looser fitting pin a player can also over torque the cue causing it to rotate a little after the facing is made thus causing stress on the wood fiber of the female threads. With metal to metal this far less critical and is a moot point unless someone is breaking with a loose joint.

There are a gazillion shafts out there where the wood fiber threads are gone and the cue is being joined by the apex of the metal thread interfacing the remaining hole where the female threads have been degraded into a very small helix groove remaining within the hole. It is astonishing how little it takes to make the facing required to play pool before it fails altogether. Cue repair guys see this everyday. Engineers without experience with cues on a daily basis don't have industry specific experience and should understand that cue joinery has to stand up to dynamic shock loads and that a big pin metal to wood or insert material produces a hit that is desirable to most players. A double edged sword for sure.

It is more than just a torque spec out of a book for metal to metal nuts and bolts going on here and there is a root cause and lesson to be learned which takes time and experience to get the big picture. Someone who has expert tire knowledge selling tires to consumers would be totally lost concerning NASCAR tire requirements for +200 mph conditions.

Good Cue Making,

Rick

 

[pdcue]

You are missing the point...
When some one says a cuemaker is not trying to improve tolerances and sloppynes in a "engineerd" standard thread but making a "unconventional" one just to be special-it's not always true..They are done for a reason.

Doing the simple test I mentoned gives a indication of the difference-of course no one is playing like this.....It's obvious.

As Steve mention, the "engineerd" threads are made to certain tolerances. If the supplier of these items is not holding these, then you either make your own joint bolt or make your own incerts for the standard threads or make it all your self in "engineerd" dimmentions.

Mezz has done the first, some do the last, one is called a bastard thread and those making "engineerd" threads with closer tolerances than what you buy stock is "ok".

To the OP-sorry that the discussion has taken off-PM me if your buddy needs help and I'll do my best to help.

My last post on the toppic.

K

I see you're STILL missing the point.

Dale

 

[scdiveteam]

Good points, all, Rick.

We were arguing two different things, thanks for making me see that.

dld

DD,

Arguing with an engineer is not smart and I know everything you were saying was mechanically correct. We are working with wood and it is a funny material when you talk numbers.

Thanks,

Rick