Carom Cues - Double Joint Shaft
- Thread starter maldito
- Start date
I played with one recently, an Adam.
Very stiff, much harder hit than the old style (male threaded shaft) regular wood cue I have.
Very stiff, much harder hit than the old style (male threaded shaft) regular wood cue I have.
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may i ask what is a double jonted shaft?
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Badass!
The threaded pin is one joint and then the inner circumference of the joint is threaded (same tpi, of course) and the pilot on the shaft threads into that....joint 2.
Check out this joint
tomatoshooter
Well-known member
That seems like "double threaded", when I saw "double jointed" I was expecting a 3 piece cue.
I hear ya...had to have one in hand to learn what itt was, myself
tomatoshooter
Well-known member
I figured out what you meant so you explained it well. I'm wondering what the setup is like to clock the threads properly. If I'm understanding properly, the threads must be synchronized.
Yeah...that's the matching tpi part, threads per inch?
When the shaft is new there are no threads outside the pilot. Once you assemble the cue, they magically appear. Like magic.
Or like metal threading onto wood.
i know the info below is about pool cues but i think the info is relevant
here is a thread about viking "super joint"
and here is a pic of the viking "double joint"
here is a thread about viking "super joint"
The old Viking "Super Joint"
I'd like to know a lot more about the Viking "Super Joint." So, I'm turning it over to the years of experience and expertise found right here. Thank you! BOXCAR
forums.azbilliards.com
I think that with two sets of threads the problem is to get the force evenly shared between the two. I think that's very hard to produce in practice. The set that's more securely anchored is going to end up with most of the load and the other set will just be along for the ride.
But if the threads are equal, wouldn't the grip be equal?
Imagine both are nice and tight. Then loosen one set by a tenth of a turn and reglue it. It will just be sitting there doing nothing. Unless you can assure that one set is exactly indexed (turned) to match the rotation of the other set, they can't both be tight at the same time.
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I'd like to think current manufacturing processes are able to get those threads matched up right.
Makers have had this index thing down for quite some time, no?
I'd like to think...
tomatoshooter
Well-known member
If it's a reputable manufacturer with modern equipment and a good process, sure. If it's the manufacturer that's responsible for absolute and total unavailability of properly threaded iron pipe, I'm not so sure.
Considering that with standard threads, you cut one, you cut the other, and they fit and the double threads, inner and outer thread must be synchronized with each other and the other end must be synchronized to those, so you have 4 parts needing synchronization. Half the mechanical beauty of the screw is that it doesn't need this synchronization. Add to that the necessity for ultra precise tolerances for both threads to engage, although this could be fixed by lapping the threads until they wear into synchronization, and, as much as I think it would be fun to try to make one, I can't see the point.
The primary force acting on a cue is hopefully axial compression. All the joint needs to do is hold the two pieces together so that they bear on each other effectively. There is also the radial stiffness component. This requires the pin provide sufficient tension that the joint faces will have a greater force holding them together than the force trying to bend the cue is prying them apart.
The double joint looks cool but I am unconvinced that it could provide any advantage, at least not enough to overcome the drawbacks. That said, if I saw a cue with one in a pawn shop, I would probably buy it because it is kind of cool.
tomatoshooter
Well-known member
There's a lathe operator who just had a nervous breakdown.
I think you might be right if we assume there's no attention to this issue. I'm thinking of the old Viking Super Joint.
Did they consider this or not?
We may never know.
I think its possible, but the maker has to pay attention. $$$
It says triple threaded, and it looks like there should be threads on the exposed wood of the shaft, but I don't see any. I doubt that the wood/metal contact would do much good anyway.
For the two sets of threads on the pin, I imagine it would not be hard to get the spacing correct, but I think it's pointless. I've heard that for a standard screw connection, three threads basically do all the work. The force is not distributed along the full length of the screw because the metal stretches enough where the the threads are working that the far threads are slack. Or so the theory goes. Any mechanical engineers/machinists here?