What is a balance shaft

what is a balance shaft

Pool Cue Information

. how to select, characterize, maintain, and use different types of pool cues.

balance point

What is the "balance point" of a cue, and does it affect shot performance?

A cue's balance point is its center of gravity, which is the point at which you can balance the cue (e.g. if you support it on a finger). Obviously, the balance point needs to be in front of the grip hand; otherwise, the front of the cue would lift up off an open bridge. Other than that, the balance point is mostly unimportant (except for personal preference based on "feel"). The balance point certainly does not impact shot effectiveness, even for follow shots with an open bridge. The CB is long gone before the bridge even feels the effect of the tip-CB collision, as demonstrated in part 2 of the following video:

Now, a shaft that is heavy on the front end (moving the balance point forward) will affect cue ball deflection, which does affect shots with sidespin. For more info, see the squirt endmass resource page .

How do you clean and maintain a cue?

Wiping with a damp rag and rubbing dry with a dry rag usually does the trick fairly well, especially if done regularly. Mr. Clean (or generic brand) Magic Eraser (dry or slightly damp) also does a very good job.

from JoeW:

I have been cleaning cues for many years and have tried many systems because I like a clean stick. About one year ago someone mentioned trying Mr. Clean's Magic Eraser. You can buy these in most any grocery store. I have found there is nothing better to return a cue stick to a like new condition.

Dampen the sponge like Magic Eraser and wipe down the cue including the ferrule. Wipe the excess moisture (there should be very little) and the grime off the cue with a cotton towel.

You can use a dollar bill to burnish the stick if you want to be like the old time pool players.

The best way to slick the cue that I have found is to use an old piece of leather. Could be a piece cut from a belt, the tongue of a shoe or whatever. Soft natural leather is all that is needed.

Wind the leather around the cue and move it as fast as you can up and down the first 18 inches or so. This will heat up and seal the cue. It is almost ready to use.

Wet the edge of the cue tip liberally with saliva and then burnish this with a dollar bill or the back of a piece of emery cloth (that is what I use). This will make the tip look nice but more importantly it will help to harden it and it will be less likely to mushroom.

from Majic:

I smooth the shaft after using the magic eraser and burnish it. I also use a dry film lubricant afterwards and this helps seal as well as provide a slick surface. Some people I know use Rain-X. RZ-50 made by Dupont is a clear product just to mention a couple. If you decide to experiment with other products just be certain is doesn't dry with a white film.

From eb_in_nc:

There's a product on the market called Q-Wiz. It's a double sided pad, the one side for roughing, the other for polishing. It is a high tech micro abrasive that won't burn through the finish and reduce the diameter of the cue. I've been using it for one year and love how it works. It's also washable and reusable.

dent removal

How do you repair a dent in a wood shaft?

If the dent really is a "dent" (where the wood fibers have been compressed) and not a "gouge" (where wood has been removed), try putting a drop of water on the dent (e.g. with a cue tip) and let it sit and dry over night. This usually helps swell the fibers back up, restoring the shaft close to the pre-dent condition. If it doesn't work completely the first time, try again. If the dent pops out too much, lightly sand with very-fine-grit sand paper.

elevation effects

What effects does cue elevation have on a shot, and how should I change my technique when jacking up the cue?

When you "jack up" your cue, by raising the butt (back) end, several bad things can happen, including:

  1. If you don’t hit exactly on the centerline of the CB (either intentional or not), the CB will swerve and go off line more (see NV 4.14 and HSV B.10 ). Some people have more success getting a center-ball hit on an elevated-cue shot by focusing on the CB (instead of the OB, as normal) during the final stroke.
  2. It can be more difficult to visually align the cue with the desired aiming line of the shot.
  3. More elevation causes the CB to hop; and with more speed, the CB will hop over a longer distance and possibly hit the OB while still bouncing. If the CB hits the OB while airborne, the cut angle will be changed and you might miss the shot (see jump shot over cut ).
  4. The more you elevate the cue with draw shots, the less spin the CB will have when it gets to the OB, for a given tip offset and cue speed (see draw-shot cue-elevation effects for more info). However, elevation does help create quick draw. and it might be required in some situations (see draw-shot cue-elevation effects ).
  5. The more you elevate (and cause the CB to hop) with the break shot, the less speed the CB will have when it hits the rack. For more info, see break shot CB squat and hop .
  6. It can be more difficult to achieve long-distance draw with an elevated cue (see jump shot cue elevation effects ).

However, sometimes cue elevation is required to shoot over an obstacle ball or rail cushion, or to avoid a double hit when there is only a small gap between the CB and OB, or to execute a jump or masse shot. And some people might need an elevated bridge for back or shoulder issues or on draw shots if they have trouble lowering or flattening their bridge.

Items 1 and 2 above are often due to one's vision center not being aligned properly when elevated. This is a very common problem. One approach to solving this problem is aiming the shot in a level-cue position and then elevate the cue from this aim (like a lot of people do when aiming jump shots). You can also glance down at the cue in the elevated position to make sure your vision center is over the cue. Disc II of "How to Aim Pool Shots" (HAPS) covers these techniques in detail.

Some of the technique advice normally suggested for jump shots also applies to other elevated-cue shots. For example, your stance and grip can be much more comfortable if you bend your bridge arm and choke up on the cue, allowing you to get closer to the cue and CB, also enabling a more comfortable and consistent stroke. It also helps to make sure you have pressure on your bridge hand and keep it as still as possible.

When jacking up the cue, one must be aware of the effects on effective tip offset (and the amount of spin imparted). Some people have trouble perceiving this effect. The following diagram from "Draw Shot Physics - Part IV: cue elevation effects " (BD, July, 2009) illustrates the concept:

Is it possible to have the cue perfectly level at a pool table (i.e. is it possible to not have the cue elevated)?

No. Because the cue must clear over the rails, the cue must be elevated some on practically all pool shots. Here's an illustration from Patrick Johnson (from AZB post ) that illustrates why:

The cue must be elevated some to clear the rail cushion and hit the ball low enough to prevent a miscue. The cue must be elevated even more when the CB is farther from the cushion (and a fatter part of the cue is over the rail) and/or when a below-center hit is used. For example, see: TP A.3 - Minimum cue elevation required for a head-spot-to-foot-spot center-ball-hit shot .

"feel," "hit," "feedback," and "playability"

What do "feel," "hit," "feedback," and "playability" really mean in relation to a cue, and do they affect a shot?

These are qualitative phrases used to describe the force, shock (impulse), vibration. and sound a player feels and/or hears during and after (but mostly after) the cue tip hits the cue ball.

The "feel" and "sound" of a hit are affected by shot speed and how far the tip hits off center. They are also affected by:

  • tip type, hardness. and efficiency
  • ferrule type and material
  • shaft material, design, size, and taper
  • joint material, design, and construction
  • butt material, design, and construction (including the wrap and end bumper)

There are many physical attributes that contribute to how a cue "plays" and whether or not it is physically "comfortable" to a player. Here is a partial list:

  • shaft straightness
  • tip condition, type, shape, hardness. and efficiency
  • tip diameter and shaft taper. especially if a closed bridge is used
  • cue weight, balance, and mass distribution
  • the amount of endmass, which determines the amount of squirt (CB deflection)

These things can definitely affect how a cue "plays." For example, with a similar stroke and off-center hit, a heavy high-squirt cue with a hard tip will create very different CB motion (speed and direction) than a light low-squirt cue with a soft tip. The "hits" will also feel and sound very different. And with draw shots, if the CB has less speed for a given stroke (because the cue and tip have less efficiency ), more backspin will be lost due to cloth drag on the way to the OB, which will result in less draw for a given tip offset from center.

Craftsmanship, manufacturing quality, and artistry are also important attributes of a cue to some people, especially to cue collectors.

The shock and vibration is felt and the sound is heard after the CB is already gone, so they have no direct effect on the outcome of a shot; although, some people claim the "feel" is important to getting good "feedback" on the shot (indicating if the CB was struck well with the appropriate speed), but not all players place importance on this. To many, observing what the CB does is "feedback" enough.

A cue's flex or vibration can't have much to do with the physics between the tip and CB during the extremely brief (approximately 0.001 second) impact time. Most of the flex and vibration occurs well after the CB is gone. For example, see:

and

The vibration (see other videos here) affects the "feel" of the cue, but it doesn't have much (if any) effect on the physics between the tip and CB. Although, the "feel" and "sound" of a hit is related to cue and tip efficiency, which does make a difference. A stiffer cue with a harder tip will generally provide a more efficient hit (delivering more speed to the CB for a given stroke effort).

  1. Some cues hit harder than others (i.e. they provide more CB speed for the same stroke effort). This effect is called cue and tip efficiency .
  2. Some people care about the "feedback" a cue provides based on how it feels and sounds during and after a hit. For others, seeing what the CB does is "feedback" enough.

Concerning 1 above, a cue with a hard tip will generally have a higher efficiency (providing more CB speed for a given stroke effort). With a higher efficiency cue, it can be easier to hit shots that require more power (e.g. power draw shots) since slightly less effort will be required and since one's power stroke is usually more accurate with less power. For a break cue, you want high efficiency (e.g. with a stiff cue and phenolic tip) to get the fastest CB speed possible. With a finesse game, or with really slow-speed shots, a low-efficiency cue (e.g. with a soft tip) can offer more control since a larger range of stroke efforts is required to create a wide range of CB speeds. With a high-efficiency cue, it can be difficult to accurately control slow-speed shots since a small change in stroke effort makes a bigger difference in CB speed.

Regardless of the physics, there are many "qualitative intangibles" ("feel," "hit," "sound," "feedback," "quality," "style," "aesthetics," etc.) that might be psychologically important to a player even if the characteristics might not have any direct effect on the outcome of a shot. If a player is not "comfortable" with a cue or if the cue affects their "mental" game at all, then it can make a big difference in their play.

What is the purpose for the ferrule?

The main purpose for the ferrule is to protect the wood on the end of the shaft. A ferule does allow one to change the tip without damaging the shaft wood, and it might help distribute the impact forces to the shaft during tip impact. The ferrule also affects the look, feel ("hit"), and sound of the cue. A smaller and lighter ferrule results in less squirt (since the ferrule material is typically heavier than wood).

from RRfireblade:

Purpose for a ferrule:

* "Intended" to protect end grain.

* Better base for adhering tip.

* Allows for better facing of surface during a re-tipping, plus no wood removal to shorten shaft length over time.

* Protects shaft from poor chalking technique.

* Acts as a buffer to help retain shaft diameter during 'maintenance'.

* Style and appearance. Same as any other ring work.

* Tradition.

* Really nothing to be gained by not having one. (end mass can be equaled or even reduced with the right ferrule material)

from Cornerman (concerning why a ferrule is used):

Tradition. It's a good bet that a ferrule pre-dates the tip. Chalk pre-dates the tip which means shafts were subject to split ends and needed protection or repair. With a tip and pad, no ferrule is needed.

from ShootingArts:

. there are almost endless materials to make ferrules out of including the pool balls themselves. Ferrules can be lighter than the wood, heavier than the wood, stronger than the wood, weaker than the wood, stiffer than the wood, more flexible than the wood, on and on. In addition the adhesive use to hold the ferrule on may offset the tiny difference in weight savings of some ferrules.

The ferrule was developed long before we had the quality adhesives that we have now. The pads we use now serve the same purpose the ferule once did, to keep the wood from splintering. Note that ivory ferules normally have a pad installed to prevent them from splintering.

Ferrules are decorative, they may help us aim by giving us an easier to see point to focus on, and they can be chosen to serve a purpose, mostly giving a softer hit. A hard ferrule stiffens the hit compared to a soft ferule but I'm pretty skeptical of a hard ferule and 29" of wood giving an detectably stiffer hit than 30" of the same wood. What the hard ferrule may do is change the sound of the hit a little.

What is different about a jump cue and why does it jump better than a typical playing cue, especially a playing cue with an LD shaft?

Jump cues are shorter, lighter and stiffer, with a hard tip (e.g. phenolic). All of these features make it easier to get more rebound height off the table slate with a legal hit (i.e. not an illegal "scoop" jump shot ).

An LD-shaft playing cue doesn't jump as well because the hit is less efficient and the tip contact time is longer, especially compared to a jump cue.

To get good jump action, it helps to have a hard tip (e.g. phenolic), a stiff shaft, and a light cue (resulting in faster cue speed). The hard tip and stiff shaft generally result in a more efficient hit (i.e. more speed will be delivered to the CB for a given cue weight and speed). For more info, see cue efficiency. The hard tip, stiff shaft, and fast speed also help reduce cue tip contact time. For more info, see the cue tip contact time resource page. A shorter tip contact time is important to allow the CB to separate from the tip before the CB interacts too much with the table surface. If the tip is still in contact while the CB is interacting with the slate, the CB won't jump as well.

Compared to a typical good-action jump cue, a typical LD-shaft playing cue has a softer tip, a less-stiff shaft, more weight, and less speed during a jump stroke. All of those things can hurt when it comes to jumping the CB.

Also, if the cue tip does not get out of the way while the CB is bouncing off the slate, a poor jump can result. This can be caused by poor jump shot technique (e.g. hitting the CB too high, or using a grip that is too tight), but having a light jump cue also helps since it will lose more forward speed with the hit.

laminated shafts

Why are some shafts (e.g. some LD shafts) laminated, consisting of layers or radial segments glued together?

Laminated shafts can have better strength and consistency with lower-quality cuts of wood. They can also have better dimensional stability, being less prone to warp over time. Also, shafts of the same brand and model will tend to be more consistent because there is less chance for wood grain variance, as compared to a solid piece of wood.

low squirt (low deflection or LD) shafts

Can a low-deflection (LD) shaft help my game?

An LD shaft has less "endmass " than a regular shaft. As a result, it creates less cue ball squirt. I prefer the phrase "low squirt" to "low deflection" or "LD" (for more info, see "squirt," "deflection," "stiffness" ).

"Squirt - Part V: low-squirt cues " (BD, December, 2007) summarizes the results of a poll concerning whether or not a low-squirt shaft helps and who it helps. The article also presents a logical analysis with a graphical interpretation explaining how a low-squirt shaft can help. The assumptions of the analysis are similar to what Shepard describes in an example in his Everything you Always Wanted to Know About Cue Ball Squirt, but Were Afraid to Ask article.

BTW, here's the last line of the article. my answer to the question of whether a low-squirt shaft can help is: yes, especially if you believe it can help you. The mind is a powerful thing. I use a low-squirt cue and I think I play better with it; therefore, I probably do. I wrote this because the analysis shows only a small expected increase in accuracy with a low-squirt cue for a player with decent squirt knowledge/intuition. Although, a novice player who knows nothing about squirt and how to compensate for it can definitely benefit (a small amount) from a low-squirt shaft, especially when they use english (intentionally or not). The CB will go closer to where they are aiming. That's usually a good thing. Now, if the tip is aligned center-ball to begin with and the unintentional english is applied with a "swoop" (non straight) stroke, whichever cue has a natural pivot length (or effective pivot length) best matched to the player's bridge length will be the best at reducing the effects of squirt (or the net result of squirt, swerve, and throw ).

Here is a summary of possible advantages of low-squirt shafts:

- The CB will come off the cue tip closer to the aiming line when using sidespin. Therefore, not as much aim adjustment or compensation is required when using sidespin. For people who aren't good at compensating for squirt, this can be very helpful. Also, with less compensation, there will be less error. For more info, see Diagram 2 and the surrounding discussion in "Squirt - Part V: low-squirt cues " (BD, December, 2007).

- A player might be more consistent with shots with sidespin since the possible range of squirt is smaller than with regular shafts. Basically, if there is less squirt then less aiming adjustment is required. For more info, see "Squirt - Part V: low-squirt cues " (BD, December, 2007).

- With a bridge length well matched to the natural pivot length of a shaft, the effects of any stroke swoop (intentional or unintentional) will be canceled. This can be particularly useful with a break cue, where stroking errors are more likely. For more info, see Diagram 4 in "Squirt - Part IV: BHE, FHE, and pivot-length calibration " (BD, November, 2007).

- Squirt resulting from unintentional english due to slight errors in off-center alignment will be minimized.

- It can be possible to get slightly more spin on the CB with a low-squirt shaft, but this effect is very small. For more info, see getting more spin.

- Many low-squirt shafts are constructed as a radial laminate (long wedge-shaped sections glued together and then turned down on a lathe), so they are more likely to hold their straightness over time (i.e. they are less likely to warp). If the wood laminates are chosen carefully (e.g. with a certain grain orientations), this might help improve strength. Also, this could help with consistency from one shaft to another of the same model. Some people think the radial consistency also helps create a more consistent "hit," regardless of the orientation (twist angle) of the cue, but this effect is questionable. Some people think radial consistency also helps create more consistent squirt, but that effect is also questionable (see "Squirt - Part VII: cue test machine results " - BD, February, 2008).

Low-squirt shafts might not be good for everybody. Here are some possible disadvantages of low-squirt shafts for some people:

- Low-squirt (LD) shafts currently available can be expensive.

- If somebody is used to compensating aim with a higher-squirt cue, it might be difficult to adjust to the lower-squirt cue.

- Some people might not like the "feel" or "hit" or "sound" or "look" of a low-squirt shaft.

- It can be more difficult to masse or jump the CB (e.g. when wanting to jump over just the edge of a ball) with an LD shaft.

- Some people might not like the small shaft diameter or taper of some low-squirt shafts, especially if a closed bridge is used.

- A low-squirt shaft might not be as mechanically sound over long-term use (i.e. the shaft end is not as strong and tough).

- If someone hits lots of low-speed sidespin shots, and he or she is used to a higher squirt helping to cancel some or all of the swerve,

then he or she might have trouble adjusting to a low-squirt shaft (where more swerve compensation would be required for these shots).

- Low-squirt shafts have long natural pivot lengths. which might not be appropriate for either BHE or FHE on certain shots. Therefore, there is no simple aim-and-pivot squirt-compensation method. a "combination" of BHE and FHE will be required. For more info, see back-hand and front-hand english .

- If you have a short bridge length, a low squirt cue could result in more directional error (as compared to a regular squirt cue with a shorter pivot length) due to any unintentional pivot during your stroke.

- If you are used to a low-squirt cue, and you find yourself in a place without your cue, where only regular-squirt cues are available, you might not play very well (until you can adjust).

- A low-squirt cue will not make it easier to compensate for swerve and throw. To aim shots with sidespin, many factors need to be taken into consideration. For more info, see aim compensation for squirt, swerve, and throw .

from Patrick Johnson:

Each increment of tip offset equals more squirt with a high squirt shaft than the same increment with a low squirt shaft - so the same tip placement error has greater effect with a high-squirt shaft.

The effect of tip placement errors is higher or lower for two shafts in the same ratio as the squirt produced by the two shafts. If a shaft produces 1/3 more squirt, then tip placement errors have 1/3 more effect.

What is the difference between a low-deflection shaft and a low-squirt shaft?

Nothing. They are the same. A low-squirt shaft creates less ("low") cue-ball squirt but actually results in large ("high") cue deflection (because the end of the shaft is lighter and usually more flexible. so it deflects away from the CB more with an off-center hit). So a "low"-deflection shaft actually has "high" deflection.

This is why I and others prefer the term: "low-squirt shaft" because it results in less CB squirt. A "low"-deflection shaft has low CB deflection, but high cue deflection. Also, what the shaft is doing (deflecting) is not important. What the CB is doing is what counts. The CB squirts less with a low-squirt shaft.

Does a low-squirt shaft allow me to put more spin on the cue ball?

The short answer is: No.

Here's a longer answer:

Per "Squirt - Part II: experimental results" (BD, September, 2007), a common low-squirt shaft has a squirt angle of about 1.8 degrees at close to maximum tip offset, as compared to 2.5 degrees for a typical regular-squirt cue. So a low-squirt shaft offers only about 30% less squirt than a typical regular-squirt cue. Per TP B.7. if you calculate the effective offsets using the squirt angles above, the percentage change in effective tip offset and the resulting spin for a given actual tip offset is 2-3%, so this effect is small. The diagram at the top of TP B.7 shows an exaggerated illustration of how the "effective tip offset" differs from the "actual tip offset," and how this depends on squirt. With an LD shaft, to get the same amount of spin (i.e. the same effective tip offset), the actual tip offset will be slightly less than with a non-LD shaft. But, again, this difference is very slight in a comparison of typical LD vs. non-LD equipment. Also, if a shaft had much more endmass (much more than a slight amount more), you would be able to hit farther out on the CB, with a larger actual tip offset, to get the same effective tip offset (and spin) produced with the LD shaft. Therefore, an LD shaft cannot produce more spin; although, the aim and tip offset will be slightly different to get the same amount of spin. For an extreme example of this, see the video and info on the miscue-limit squirt effects page .

Now, when comparing cues and/or tips, it is important that the tip offset is the same for both. If the tip size and shape are different, and one uses "tips of english" as a measure, perceived tip offset can be very different than actual offset, resulting in significant differences in the amount of spin. See the "tips" of english resource page for more illustrations and explanations.

LD shafts typically have smaller-diameter tips than non-LD shafts. Because of this, a person might tend to place the tip farther from center than with a thicker non-LD shaft. Obviously, this would apply more spin to the CB (as long as the tip contact point is within the miscue limit).

The shape of the tip can also make a difference. For more info, see the illustration on the cue tip size and shape effects resource page.

Also, with draw shots, if someone is accustomed to a larger shaft that is close to touching the cloth at CB address, and they place a smaller diameter shaft in that same apparent position (close to the cloth), the effective tip contact point offset on the ball will be lower.

For more info on LD shaft spin effects, see:

Also, tip harness can have a slight effect on the amount of spin that can be applied for a given tip offset. For more info, see the cue tip hardness effects resource page .

from Patrick Johnson:

Can one cue stick produce more spin than another? No.

The force of a stick's momentum and the force produced by its squirt are combined into a single "force vector" that points through the CB in the direction the CB will travel. So when a stick is pivoted at its Squirt Pivot Point to hit the CB at a given spot, it produces the same "force vector" as any other stick doing the same thing, no matter what its angle of approach (the same as a theoretical unpivoted "no-squirt" cue).

The CB can't tell which direction a stick is pointed - it can only "feel" the direction and magnitude of this "force vector". And since every stick produces the same "force vector", every stick "feels" the same to the CB and the CB reacts the same way to each.

masse cue

What is different about a masse cue?

Masse cues are typically shorter, heavier, and stiffer, and typically have a larger shaft diameter and tip. The shorter length is to improve handling and reduce overhead clearance problems. The extra strength and stiffness are for durability and better action. The extra weight can also help you get more action with less effort.

natural pivot length

How do I determine the natural pivot length for my shaft, and why should I?

"Squirt - Part IV: BHE, FHE, and pivot-length calibration " (BD, November, 2007) explains and illustrates back-hand english (BHE). front-hand english (FHE), a cue's natural pivot length, and advice for selecting a break cue.

Here's a procedure recommended by Colin Colenso for measuring a cue's natural pivot length:

Place OB about 6 inches from a corner pocket. Align CB in a straight line with this about 5-6 feet away. Align to pot straight, pivot and hit the shot near maximum speed to ensure insignificant swerve. Adjust bridge length until you consistently have the CB hitting pretty much at the original aim.

It's pretty obvious when you're hitting this shot within 1/10th inch of center which allows you to narrow down the intrinsic pivot point to less than an inch. The CB would spin on the spot if the OB was hit about 1/20th inch off center. This is plenty of accuracy over 5-6 feet. Pretty much as accurate as one could hope to aim the initial pot.

"Squirt - Part IV: BHE, FHE, and pivot-length calibration " (BD, November, 2007) also presents a simple procedure for measuring the natural pivot length for a cue; although, throw is more of a factor in these measurements. The procedure in the article yields more of an "effective pivot length," which compensates for both squirt and throw. This pivot length will be longer than the actualy natural pivot length.

With a bridge length well matched to the natural pivot length of a shaft, the effects of any stroke swoop (intentional or unintentional) can be canceled. This can be particularly useful with a break cue. where stroking errors are more likely. For more info, see Diagram 4 in "Squirt - Part IV: BHE, FHE, and pivot-length calibration " (BD, November, 2007).

Having the natural pivot length well matched to your preferred bridge length can also be important if you use back-hand english (BHE) to compensate for squirt when using sidespin. For more information, see the BHE resource page .

TP B.1 uses physics and math to predict the natural pivot length for a cue from squirt angle measurements. Here are some of the conclusions supported by the analysis:

- Squirt angle varies nearly linearly with tip offset, and tip offset varies nearly linearly with cue pivot angle. This is what makes the BHE and FHE methods effective, provided swerve and throw are also taken into consideration.

- A cue's natural pivot length does vary a little with both tip offset and tip shape (radius), so when comparing different cues with experimental measurements, it is important to use the same tip shape and the same amount of tip offset (english) for each cue.

- Cue pivot lengths reported by Platinum Billiards report a range from 8 inches (for a "high-squirt" cue) to 14 inches (for a "low-squirt" cue). Numbers from Colin's procedure (see above) seem to back up this range.

- Expected cue pivot lengths reported in Ron Shepard's 2001 paper "Everything you Always Wanted to Know About Cue Ball Squirt, but Were Afraid to Ask " appear to be much too large. He reports a range from 10 inches (for a "high-squirt" cue) to 50 inches (for a "low-squirt" cue).

For more information about squirt (AKA "cue ball deflection") and how it is related to the natural pivot length of a cue, see the squirt (cue ball deflection) resource page .

from Patrick Johnson:

The traditional "aim-and-pivot" squirt test keeps the balls at the same distance and pivots the shaft to different angles by shifting the bridge hand (pivot point) back and forth until the shot is made.

This Simple Squirt Test keeps the shaft aimed at the same two points on the CB and OB while changing the distance between the balls until the shot is made. Changing the distance between the balls while aiming at the same points on them changes the angle of the cue in (hopefully) a more controlled way that can be more accurately measured.

Is there a pivot point for a cue that will compensate for throw and/or swerve in addition to squirt?

Unfortunately, the amount of throw varies with cut angle, shot speed, type of english, amount of topspin or bottom-spin, and ball conditions. Also, swerve depends on shot speed, shot distance, cue elevation, amount and type of sidespin/roll, and ball/cloth conditions. Therefore, it is difficult to predict a required cue pivot point to compensate for anything more than squirt. Maybe this could be done for medium speed shots, at medium distances, with a medium amount of sidespin (with a consistent amount of draw or follow); but otherwise, aim-and-pivot aim compensation alone is not adequate to account for all of the subtleties associated with squirt, swerve, and throw. Having said all of that, aim-and-pivot methods (e.g. BHE and/or FHE ) can still be very helpful to many players on many shots.

How much deflection does a cue of given pivot length produce?

from Patrick Johnson:

Knowing your cue's Pivot Length is the basis for a simple method of visualizing squirt correction that can reduce the guesswork.

Pivot Length is the distance from your cue's tip to its Pivot Point, the place to pivot your cue to apply squirt-correcting backhand english. This is because (here's the useful part ->) Pivot Length is the distance the CB travels to be off target by exactly the same distance as your Tip Offset from the CB's center .

That means you should aim your shot one Tip Offset to the side of your target for each Pivot Length between the CB and the OB (minus something for swerve ).

Here's a drawing with some detail about how to do that. For illustration it assumes a Pivot Length of exactly 12.5 inches (1 diamond on a 9-foot table), which is probably not an uncommon "high squirt" Pivot Length. Of course, each cue's Pivot Length can be different.

"squirt," "deflection," "stiffness"

How is cue deflection related to ball squirt?

These terms can be confusing and misleading. Here's my summary:

"low-deflection" (LD) shaft

= "low end-mass" shaft

= usually flexible (AKA "whippy", compliant, not stiff, "like a wet noodle") shaft end

An LD shaft. due to its smaller endmass. is usually whippy close to the tip. This causes the shaft to bend or flex (i.e. "deflect") a lot during an off-center hit, and the low endmass results in less squirt (cue ball "deflection"). This is why the term "deflection" can be misleading. A low-deflection shaft actually deflects more than normal as it creates less CB deflection. That's why "squirt" (or "cue ball deflection") is much more clear.

types and tapers

What is different about the different types of cues and shaft tapers?

Shafts are made with various tapers, the two most common being the pro taper and the European taper. The pro taper has the same diameter from the tip to 30–35 cm (12-14 inches) toward the joint, at which point it begins to widen. The European taper widens continually and smoothly from the ferrule toward the joint. Despite their names, the continually sloping European taper is found in most North American bar and house cues, and not all professional players prefer a straight pro taper on their custom, two-piece models.

From Snapshot9:

Cues can up to a 14mm tip, and lots of Break/Jump cues, or Break cues, or Jump cues have a 14mm tip because a bigger tip is better for Breaking and/or Jumping. Break cues commonly have a Conical taper (also called European) for added stiffness.

A Break/Jump cue is one that is used for Breaking and Jumping with part of butt coming off so that the shorter Jump portion can be used. Jump cues/portions are commonly

40" long, the minimum length they can be.

Leather tips are better for control, but Phenolic tips, which are harder, are better for power and/or lift when jumping. I have a J&J Break/Jump cue with a phenolic ferrule/tip combination that I like a lot, and they can be bought for $60/65 dollars. I used to believe in separate Break cue and jump cue, but the J&J Break/jump changed my mind about that, and a Break/jump combo takes up less space in your case. Phenolic tips do some getting used to though, and almost require a center ball hit.

A standard taper started out 8-10"

A pro taper started out 10-13", now is 13-15"

An European taper is like a long cone shape, with no part of the shaft being the same diameter at any 2 points. (constantly tapers down to the tip).

There is also a straight taper, which a lot of Snooker cues have.

vibration

How much and in what manner does a cue deform and vibrate during and after a shot?

Here are some excellent super-slow motion videos illustrating cue vibration effects with sidespin shots:

Here's an excellent article from Alexander Sorokin presenting technical results of some experiments on this topic:

Some additional examples of accelerometer measurements can be found here:

The amplitudes, frequencies, mode shapes, and durations of cue vibration are big factors in determining the "hit" or "feel" of a cue .

There two types of waves that travel through the cue during vibration: "longitudinal" waves (done the length of the cue). The speed that these waves travel down the cue is directly related to the speed of sound in the cue material. This wave travels very quickly from the tip to the joint and butt end and back while the tip is in contact with the cue ball. If it didn't, the entire weight of the cue would not come into play during the tip-CB collision (but it does).

There are also "transverse" or "lateral" elastic waves that corresponds to deflection of the tip perpendicular to the shaft (in the squirt direction). These are the waves most visible in the videos above. Transverse elastic wave moves much more slowly than the longitudinal wave. Their speed depends on the lateral stiffness of shaft and cue. The transverse wave affects how much "effective endmass" a shaft has, and therefore how much squirt (cue ball deflection) the shaft produces with a off-center hit.

What is the optimal weight for a cue?

For your main playing cue, use whatever weight feels most comfortable. A heavier cue will tend to create more CB speed for a given stroke effort. A heavier cue might also be easier for some to keep on line during the stroke, but this is a very individual thing. Also, a heavier cue might tend to have a shaft with more endmass (although, this isn't necessarily so). If that is the case, the heavier cue will create more squirt (AKA "cue ball deflection"), which can have both advantages and disadvantages for different people. Another potential pitfall with a heavy cue is that it could result in double hits, pushes, or miscues at large tip offsets. For more info, see maximum english .

Now, for a break cue, the optimal weight for maximum cue ball (CB) speed will depend on your arm anatomy (the size and weights of the different parts of your arm), muscle physiology (e.g. fast-twitch vs. slow-twitch muscle fiber dominance), technique. and timing. The only way to find out the optimal weight for sure is to experiment. Cue weight is not just a question of physics. Physiology also comes into play. Some people have more fast-twitch muscle fibers than others. Because of this, cue weight selection can be a very personal thing.

What determines the CB speed is the cue's mass and the cue's speed at impact with the ball, and CB speed is what we are striving for (in addition to accuracy). For a given cue speed, if the cue has more mass, the CB will go faster; and for a given cue mass, if the cue has more speed, the CB will go faster. Both factors (cue speed and cue mass) are important. Some people can generate more breaking power with a lighter cue, and some can generate more with a heavier cue. A detailed analysis of the physics of how CB speed varies with both cue mass and speed (and tip offset from center, and tip efficiency) can be found in TP A.30. Breaking power is related to the square of CB speed, and CB speed is directly related to cue stick speed, so if you can increase the speed of your break stroke while maintaining accuracy, it can result in a big improvement in break effectiveness. And if you can also use a heavier cue, and maintain the same or similar cue speed, you can also increase breaking power; although, increases in cue weight don't have as large of a benefit as increases in cue speed (see details below).

Cue and tip efficiency can also affect breaking performance. Based on the numbers in TP A.30. changing from a medium-hardness leather tip on a typical playing cue (typical COR = 0.73) to a phenolic tip on a break cue (with a COR as high as 0.87), can increase breaking power by 17%! For comparison purposes (see the end of TP A.30 for details), if you could increase your cue speed by 10%, the cue ball speed would also increase by 10%, and the effective increase in breaking power would be 21%. And for a given cue speed, if you could increase the cue weight from 17 to 22 oz (while maintaining the same speed), the cue ball speed would increase by 6.3%, which would correspond to an effective increase in breaking power of 13%. So with a dramatic increase in cue weight (17 oz to 22 oz), the benefit is not as large as one might expect, even if the heavier cue could be stroked at the same speed as the lighter cue (which is usually not the case).

As mentioned above, the optimal cue weight for each individual, providing the best combination of cue speed and weight to produce the best breaking power, is a very personal thing. The only way to determine the optimal weight is to experiment. And even if you are using the optimal-weight cue and are generating the most cue speed possible, none of that will matter if you are not using good technique to get a square hit on the lead ball or if you are getting too much unintentional sidespin or CB hop. You should only use as much speed as you can control.

A good analogy to pool break cue weight selection is baseball bat weight selection. A lighter bat can be swung faster, but a heavier bat has more mass. Some players can generate more ball speed (and distance) with a heavier bat (e.g. Babe Ruth), and some do better with a much lighter bat (e.g. Barry Bonds). An excellent webpage dealing with baseball bat weight effects can be found here: Bat Weight, Swing Speed and Ball Velocity. Notice the ball speed vs. bat weight graphs about 3/4 down on the webpage. They are very flat at the optimal weight, implying bat weight doesn't really make that much difference in the range of typical values. This effect should be similar with break cues. If you are in your preferred weight range, an ounce more or less shouldn't make much difference.

For more information, see: "Optimal Cue Weight " (BD, October, 2015).

From pooltchr (concerning a playing cue):

1. I believe the best weight for any player is the weight that feels most comfortable for all types of shots.

2. I believe that different weights can produce slightly different results, but those differences are so slight that most good players can adapt their stroke to get the desired results regardless of the chosen weight.

3. While a long draw shot does require more speed than a shorter one (adjusting speed and or spin is the only way to control draw)we still don't need to use maximum (break) speed even for maximum draw. For that reason, I think any good player can get the required speed with any weight cue. Those same players would be able to adjust their stroke to compensate for the weight differences in various cues.

4. Since over the course of a game, a player will need to vary speed and spin from shot to shot, the most comfortable weight to the individual player makes the most sense to me. It's easier to make slight adjustments to speed and spin with a well balanced comfortable cue. You can establish a centergistic or reference point for a stroke speed follow shot, then work from there to know what is needed when you need to do something else with the cue ball.

Source: billiards.colostate.edu

Category: Forex

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