5/16-14 vs 5/16-18 Why?

HawaiianEye

HawaiianEye

AzB Silver Member
Silver Member
I sort of understand the rationale of why certain cue makers use different types of pins for different reasons (weight, hit, etc.), but why would one use one of these pins over the other?

It seems that "cheaper" and "production" cues are more likely to have a -18 instead of a -14...is it due to cost or something?
 
HawaiianEye said:
I sort of understand the rationale of why certain cue makers use different types of pins for different reasons (weight, hit, etc.), but why would one use one of these pins over the other?

It seems that "cheaper" and "production" cues are more likely to have a -18 instead of a -14...is it due to cost or something?
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I think the 5/16" x 18 is a more common thread in industry, hence the cheaper cues have it. Probably more readily available and easier to obtain tooling to produce it, etc. Again, just my thoughts, but I have noticed it too.

It also seems that the majority of the 18 sizes are flat faced joints, and 14 are piloted. Again, there are exceptions but that's just what I note. My old Corsair is 5/16" x 18, but piloted...so there is one exception. :)
 
DoubleD said:
Radial threads are the most ridiculous, hilarious bastard bitc4 threads ever made and the use of them causes me to laugh hysterically.

dld
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LMAO! I agree!! but I am guilty of having tried them in the past. Back then I think Uni-loc was the only one that made them, and if I remember I paid some ludicrous amount for the tap?? I did like the little fact that they had the aligning shoulder. Are they still like this? I've been out of the business for a few years.
 
The aircraft industry going back as far as the P-51 Mustang used the 5/16-14 from what I was told years ago.

You can still buy a 3 pc tap set from Travers,so it's not a total bastard LOL.

As far as the Radial,I'd still like to know why they decided,or WHO decided to use the 7.634 pitch (Bill Stroud?) rather than an 8.

The 8 would be much easier to cut on a manual lathe,not only because 8 is easily set on the gearbox,but you can use an .125 radius parting tool to cut it.

That would also make it easier to have a tap made,or make your own.

The 7.634 has to be done CNC,and with a .1309 radius cutter. That means having to use a surface grinder to make the cutter blank the right width,PLUS getting the radius perfectly round.

Either that or you have custom inserts made.

Cuemakers aren't the only ones that use oddball threads. There is a particular bolt on Honda dirt bikes that their engineers came up with that is a 6.5mm diameter,but instead of a metric pitch,is threaded at 32TPI. Tommy D.
 
DoubleD said:
JAlan has it correct.

5/16-18 is a very common machine screw thread. You can literally walk into any hardware store in the U.S. and buy a 5/16-18 machine screw or threaded rod--any good hardware store will have rod in brass, steel and stainless steel. You can also buy taps for a few dollars each.

5/16-14, on the other hand, is a thread that some cue maker invented so someone could save maybe three rotations of the shaft while screwing the cue together. It is a bastard thread which serves absolutely no practical purpose except to save some fraction of a second in assembly of the cue. Taps, threaded rod and inserts are available only by making your own or purchasing from a cuemaking supply store.

The same can be said for 3/8-10 and 3/8-11, except that they actually do serve a purpose. The threads on the 3/8 pins are much coarser than machine screws--this becomes important since the 3/8 pins usually thread into wood.

Radial threads are the most ridiculous, hilarious bastard bitc4 threads ever made and the use of them causes me to laugh hysterically.

dld
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There is one difference though. 5/16 x 18 you buy at the hardware store in most all cases are almost useless for a pool cue joint. They are not made to any kind of strict specs. I have some I bought that measured from .290 to .301 all over the rod and in almost every rod very undersized. Plus, the quality of the threads themselves were horrible. I finally ordered some from a supplier who does cue stock. "What a difference". Beautiful threading, consistent diameter for a nice smooth close tolerance fit. The difference in fit and quality was night and day.

I am not sure you could find screw stock this quality in any off the shelf store. It has to be made with quality as the number 1 objective. With the right quality screw stock, 14 or 18 are pretty much the same. You could even argue that 18 is a little better because of the added threading for a smoother fit.
 
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Tommy-D said:
The aircraft industry going back as far as the P-51 Mustang used the 5/16-14 from what I was told years ago.

You can still buy a 3 pc tap set from Travers,so it's not a total bastard LOL.

As far as the Radial,I'd still like to know why they decided,or WHO decided to use the 7.634 pitch (Bill Stroud?) rather than an 8.

The 8 would be much easier to cut on a manual lathe,not only because 8 is easily set on the gearbox,but you can use an .125 radius parting tool to cut it.

That would also make it easier to have a tap made,or make your own.

The 7.634 has to be done CNC,and with a .1309 radius cutter. That means having to use a surface grinder to make the cutter blank the right width,PLUS getting the radius perfectly round.

Either that or you have custom inserts made.

Cuemakers aren't the only ones that use oddball threads. There is a particular bolt on Honda dirt bikes that their engineers came up with that is a 6.5mm diameter,but instead of a metric pitch,is threaded at 32TPI. Tommy D.
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There is a metric thread that is almost identical to 32 TPI.

I would assume the reason for the very odd ball thread count on the Radial is to where people would have to buy pins and taps from them. Solely a marketing move. Just like the introduction of the 11 pitch shaft thread. That made it to where 90 percent of shops could not make a shaft for the SW cues at the time.
 
DoubleD said:
You are absolutely wrong on all of this. Just because the one piece of threaded rod you measured did not comply does not mean there is not a tight standard.

Pretty much all UNC, UNF threads are undersized.

I can buy off-the-shelf threaded rod that is gorgeous.

As far as being 'suitable' for holding two pieces of wood together, tightened by hand...I don't even know where to begin to prove to you that is incorrect.
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I didn't mean to offend you, I live in a boating area and SS is available all over the place. It is all pretty much crap compared to what is made by a supplier of screw stock just for cue makers.

It may not be crap to make fasteners for marine pieces but on cues it would look horrible. The thing is, you can order really high quality screw stock for about the same price as the stuff from the boating supply or hardware store. I take your word for it you have bought good stuff but I have to say, I never have, at least not as nice as from a good supplier.
 
I prefer the 18 tpi over the 14 tpi because for the same radial torque on the handle and the shaft, the joint is held together 28% tighter. Or you could look at it from the point of view that it requires less torque to achieve the same clamping force on the joint faces.

The greater the helix angle, the less clamping pressure can be applied and the screw has a greater tendency to loosen.
The course threads into the wood , work because of the yielding of the fibers along the pitch of the screw.

I had a G clamp and put slick50 grease on the threads and on the thrust face. The clamp was useless, as it kept unscrewing. It needed the friction on the thrust face and the threads to stay closed. Learnt something that day.
 
5/16 X 14 is leftover from the war, 5/16 X 18 came from standards after the war.I would imagine the early cue builders ran into the 14 tap and die stuff after the war for cheap and loaded up on it.they might even have got the stuff for free if they hauled the pile off.the second generation builders had to go the 18 stuff or find somebody to build the 14 at a big price.A lot of the old builders are from the factory towns that did work for the war.

bill
 
DoubleD said:
You are absolutely wrong on all of this. Just because the one piece of threaded rod you measured did not comply does not mean there is not a tight standard.

Pretty much all UNC, UNF threads are undersized.

I can buy off-the-shelf threaded rod that is gorgeous.

As far as being 'suitable' for holding two pieces of wood together, tightened by hand...I don't even know where to begin to prove to you that is incorrect.
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I will second that opinion, threaded rod is rolled. If you measured the pitch diameter of a three foot rod, say every inch or so. You would find it is extremely consitent in size The od of screw thread is not a important measurment. It is the pitch diameter which dictates the fit of a thread. http://en.wikipedia.org/wiki/Threading_(manufacturing)
 
Old post but it still rings true on different screws across the board.


9/32X18, 5/16X18, (used by many), .298X14, (Mali), .302X14, 5/16X13,
5/16X14 (Numerous), 5/16X14 acme,
5/16 max. radial, Uni Loc, Radial ball screw, 3/8X8 acme, 3/8X8 standard, 3/8X8, (over seas ball screw)
3/8X10 acme, 3/8X10 standard, 3/8X11.
3/8X11.5, 3/8X12, 3/8X14,
3/8X14 undersized, 3/8X16, 7/16X10, 7/16X11,
1/2X8 wood thread by a few, 1/2X13 Dufferin joint, Schmelke joint, Viking's super joint.
There are more, I quit buying taps and dies. I consider all screws correct use of individuality of the Cue maker using them and respect them rather than condemn them.
 
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