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DTL
11-04-2015, 12:51 PM
..................

SamLambert
11-04-2015, 12:54 PM
A couple of knowns (I think):

* All shafts squirt with an off center hit on the CB, LD shafts less than non-LD shafts. The more off center, the greater the squirt.
* And since the cue is almost always slightly elevated due to the rails being higher than the slate bed, the CB eventually, if given enough time before contact with the OB, will swerve back in the opposite the direction of the squirt.
* When applying BHE at a cue's proper bridge length (pivot point), squirt and swerve can be canceled out on 1-5 foot shots using a medium to hard stroke.

My question is this:

* When using parallel english, is there any shots when squirt and swerve cancel each other out? If so, how many tips of english, at what distance from CB to OB, and at what speeds? IOW, are there some shots where no compensation is needed.

DTL

Yes, but this will depend on many things:



Deflection of the cue
Speed of the shot
Elevation of the cue
How much english is applied


What prevents us from setting "known" shots where compensation is perfect I think mostly has to do with the fact that the squirt of the cueball varies depending on the cue.

In other words, your best bet I think is to try it out and see for yourself. Put 2 balls a little more than 1 ball apart at one end of the table, touching the rail, and put your cue ball somewhere along the length of the table in the middle, try different speeds and such and see where the compensation is perfect.

Patrick Johnson
11-04-2015, 01:46 PM
Yes, but this will depend on many things:



Deflection of the cue
Speed of the shot
Elevation of the cue
How much english is applied

How much follow/draw is applied
Ball/cloth condition (sticky/slippery)

What prevents us from setting "known" shots where compensation is perfect I think mostly has to do with the fact that the squirt of the cueball varies depending on the cue.
The amount of squirt is fixed for a given cue, but the amount of swerve varies with all of the conditions listed above - so it's the swerve, not the squirt, that makes things most difficult.

pj
chgo

mikepage
11-04-2015, 01:48 PM
A couple of knowns (I think):

* All shafts squirt with an off center hit on the CB, LD shafts less than non-LD shafts. The more off center, the greater the squirt.
* And since the cue is almost always slightly elevated due to the rails being higher than the slate bed, the CB eventually, if given enough time before contact with the OB, will swerve back in the opposite the direction of the squirt.
* When applying BHE at a cue's proper bridge length (pivot point), squirt and swerve can be canceled out on 1-5 foot shots using a medium to hard stroke.

My question is this:

* When using parallel english, are there any shots when squirt and swerve cancel each other out? If so, how many tips of english, at what distance from CB to OB, and at what speeds? IOW, are there some shots where no compensation is needed. Note: balls are clean, cloth is in good condition, and low humid day.

DTL

I have a video that addresses these issues

https://www.youtube.com/watch?v=mXJ7bDafTms

Patrick Johnson
11-04-2015, 01:49 PM
I have a video that addresses these issues

https://www.youtube.com/watch?v=mXJ7bDafTms
I wish you'd link to your videos more often here - they're some of my favorites.

pj
chgo

measureman
11-04-2015, 01:52 PM
I know a lot about squirt and swerve.
About 2AM I squirt and swerve to hit the toilet.
When you are half asleep you listen for the water sound. No sound you must swerve.

DTL
11-04-2015, 02:07 PM
.................

dr_dave
11-04-2015, 02:41 PM
Yes, but this will depend on many things:

Deflection of the cue
Speed of the shot
Elevation of the cue
How much english is applied

How much follow/draw is applied
Ball/cloth condition (sticky/slippery)

The amount of squirt is fixed for a given cue, but the amount of swerve varies with all of the conditions listed above - so it's the swerve, not the squirt, that makes things most difficult.From the squirt/swerve/throw effects resource page (http://billiards.colostate.edu/threads/aiming.html#English_effects), squirt and swerve depends on the following 15 effects:


1. Squirt increases with the amount of sidespin.
2. Squirt does not depend on shot speed (see squirt speed effects (http://billiards.colostate.edu/threads/squirt.html#speed) for more info).
3. Squirt increases with the amount of shaft endmass (e.g., a low-squirt cue has less endmass (http://billiards.colostate.edu/threads/squirt.html#endmass) and results in less squirt).
4. Squirt is slightly less with a heavier CB (see CB weight effects (http://billiards.colostate.edu/threads/balls.html#weight)).
5. Squerve (net effect of squirt and swerve = net CB deflection) can be zero with certain speeds and cue elevations for a given shot distance, amount of sidespin, and cue.
6. Squerve is less for follow vs. draw shots (see squirt tip-contact-height effects (http://billiards.colostate.edu/threads/squirt.html#tip_height)).
7. Squirt or squerve can be canceled using back-hand english (BHE) and/or front-hand english (FHE) (http://billiards.colostate.edu/threads/English.html#BHE) aim-and-pivot methods.
8. Swerve increases with cue elevation and the amount of sidespin.
9. Swerve occurs with practically all sidespin shots because the cue must be elevated to clear the rails.
10. Swerve is delayed with faster shot speed.
11. Swerve occurs only while the CB is sliding; once rolling begins, the CB heads in a straight line.
12. Swerve occurs earlier with sticky cloth and later on slick cloth.
13. Swerve occurs earlier with a follow shot than with a draw shot (see "Squirt - Part VIII: squerve effects (http://billiards.colostate.edu/bd_articles/2008/march08.pdf)" - BD, March, 2008).
14. Swerve angle is larger with a draw shot than with a follow shot (see "Squirt - Part VIII: squerve effects (http://billiards.colostate.edu/bd_articles/2008/march08.pdf)" - BD, March, 2008).
15. Swerve angle can be predicted and visualized using the Coriolis masse-shot aiming method (http://billiards.colostate.edu/threads/masse.html#aiming).

Mike's video is excellent. Here's another:

NV B.70 - Squirt (cue ball deflection), swerve, and throw, from VEPS II (http://billiards.colostate.edu/normal_videos/new/NVB-70.htm)

Enjoy,
Dave

bquiggle
11-05-2015, 09:22 AM
Good question and GREAT information in the replies, thanks