Skid -- why some good players advocate using outside on most shots
John Black
players advocate using a touch outside english whenever possible.
George Fels explains it near the end of his book on straight pool.
I used to think it is to eliminate or minimize throw but that didn't
totally make sense because throw would be factored into a good player's
skills. George says right, throw we can and do handle routinely. The
problem is "skid" which he defines as a very exaggerated throw that
occurs due to an excessively chalky or dirty spot on the cue ball (or
object ball). He says when skid happens, the balls cling together for a
much longer time -- so much that you can see it and you can hear it and
the final path of the object ball is surprisingly thick. I realize I
have seen examples after he defined it.
Skid doesn't happen too often but when it does, its a run killer. It
happens on lower speed shots with center ball or inside english. More
with inside english than center ball. It shouldn't happen with outside
which is why players try to use outside when possible especially with
low speed shots.
Fels goes so far as to say in a 14.1 game, you should be wiping the cue
ball down at least after every scratch. Even better to wipe it down
every rack if your opponent is ok with marking the cueball spot so it
can be replaced before the break. He says why not, they do it all the
time in golf...
John Black
** Posted from http://www.teranews.com **
lfigueroa
might skid. I especially go to the outside english on those.
Lou Figueroa
has had some good runs
killed by skid
John Black
Interesting. Its never really talked about in standard books and videos
on pool or is it?
John Black
In article <ZWESj.281477$cQ1....@bgtnsc04-news.ops.worldnet.att.net>,
lfig...@att.net says...
Ron Shepard
John Black <jbl...@texas.net> wrote:
> [...] The
> problem is "skid" which he defines as a very exaggerated throw that
> occurs due to an excessively chalky or dirty spot on the cue ball (or
> object ball). He says when skid happens, the balls cling together for a
> much longer time -- so much that you can see it and you can hear it and
> the final path of the object ball is surprisingly thick. I realize I
> have seen examples after he defined it.
I agree that skid changes the path and speed of the object ball (and
cue ball). You can also recognize when it occurs by noting the
large amount of spin on the object ball and/or the cue ball, or by
noting the cue ball or object ball jumping up after the collision.
However, I doubt that there is any way to see a change in the
collision time. A normal ball-ball collision time is about 0.0001
second, too fast to see, and even if it were to increase by a factor
of 10 or 100, I still doubt that you could actually see any
collision time increase. I also don't see any reason why the
collision time should increase, the balls don't suddenly turn into
soft rubber or anything, but that is a separate matter. In any
case, there is no practical need to hypothesize about collision time
changes, all of the effects of skid can be understood simply from
the change in friction between the balls.
> Skid doesn't happen too often but when it does, its a run killer. It
> happens on lower speed shots with center ball or inside english. More
> with inside english than center ball. It shouldn't happen with outside
> which is why players try to use outside when possible especially with
> low speed shots.
These things could be true, but I don't see any reason why they
should be. If you think that skid is caused by pieces of chalk that
get picked up from the tip or from the table over some period of
time and, due to random statistics, eventually find themselves
between the ball surfaces during a collision, than there would be
little or no relation to inside spin or any other spin with the
frequency of occurrence of skid. If you think that skid is caused
by chalk from the tip being transferred 1/2 ball rotation to the
ball-ball collision point on a single individual shot, then maybe
there would be a correlation of skid with very particular kinds of
spin, but in this case it would be say low-outside sidespin that
would increase the changes of it occurring relative to low-inside
sidespin, which is the opposite of what Fels (and others) have
discussed.
In any case, I do not know of any actual study that shows any kind
of observed statistical correlation between the type of spin and the
frequency of occurrence or the magnitude of skid. This might be a
useful study, but until it is done, I'm skeptical of the claim.
> Fels goes so far as to say in a 14.1 game, you should be wiping the cue
> ball down at least after every scratch. Even better to wipe it down
> every rack if your opponent is ok with marking the cueball spot so it
> can be replaced before the break. He says why not, they do it all the
> time in golf...
I often wipe the cue ball between racks in short-rack games (9-ball,
one-pocket, and 8-ball) for this reason. Perhaps it is mostly
habit, but skids are probably the reason I started in the first
place. I've noticed that many other players do this too. When it
comes to picking lint off the table or wiping chalk spots off the
ball, pool players seem to be borderline OCD. Even if they don't
start off that way, they become that way the longer they play.
In refereed matches, it is not uncommon to see players ask the
referee to clean the cue ball or an object ball during a game.
Referees are instructed how to do this consistently in a tournament
(usually by marking the position of the ball with a chalk cube or
with a pencil).
$.02 -Ron Shepard
John Black
ron-s...@NOSPAM.comcast.net says...
> In article <MPG.22844f096...@free.teranews.com>,
> John Black <jbl...@texas.net> wrote:
>
> > [...] The
> > problem is "skid" which he defines as a very exaggerated throw that
> > occurs due to an excessively chalky or dirty spot on the cue ball (or
> > object ball). He says when skid happens, the balls cling together for a
> > much longer time -- so much that you can see it and you can hear it and
> > the final path of the object ball is surprisingly thick. I realize I
> > have seen examples after he defined it.
>
> I agree that skid changes the path and speed of the object ball (and
> cue ball). You can also recognize when it occurs by noting the
> large amount of spin on the object ball and/or the cue ball, or by
> noting the cue ball or object ball jumping up after the collision.
>
> However, I doubt that there is any way to see a change in the
> collision time. A normal ball-ball collision time is about 0.0001
> second, too fast to see, and even if it were to increase by a factor
> of 10 or 100, I still doubt that you could actually see any
> collision time increase.
You're probably right. I'm guessing what people are "seeing" is a final
line that is out of whack with what they expect and it causes them to
declare they have "seen" the skid.
> > Skid doesn't happen too often but when it does, its a run killer. It
> > happens on lower speed shots with center ball or inside english. More
> > with inside english than center ball. It shouldn't happen with outside
> > which is why players try to use outside when possible especially with
> > low speed shots.
>
> These things could be true, but I don't see any reason why they
> should be. If you think that skid is caused by pieces of chalk that
> get picked up from the tip or from the table over some period of
> time and, due to random statistics, eventually find themselves
> between the ball surfaces during a collision, than there would be
> little or no relation to inside spin or any other spin with the
> frequency of occurrence of skid.
Huh? My understanding is that skid is exaggerated throw. Outside
couteracts throw so it would counteract skid as well. If you think of
the two balls as gears while they are in contact, outside causes the two
gears to rotate in opposite directions in which case the contact induced
throw is cancelled by the english induced throw in the opposite
direction. With inside english, the contact induced throw adds to the
english induced throw.
> If you think that skid is caused
> by chalk from the tip being transferred 1/2 ball rotation to the
> ball-ball collision point on a single individual shot,
I don't think anyone thinks that. If that were the case, wiping the cue
ball down periodically would not help much.
> In any case, I do not know of any actual study that shows any kind
> of observed statistical correlation between the type of spin and the
> frequency of occurrence or the magnitude of skid. This might be a
> useful study, but until it is done, I'm skeptical of the claim.
Not sure why you need a study. You know that english induced throw from
outside is in the opposite direction as contact induced throw and so
tends to cancel out the overall throw effect. And english induced throw
from inside is in the same direction as contact induced throw and thus
adds to the throw effect.
> > Fels goes so far as to say in a 14.1 game, you should be wiping the cue
> > ball down at least after every scratch. Even better to wipe it down
> > every rack if your opponent is ok with marking the cueball spot so it
> > can be replaced before the break. He says why not, they do it all the
> > time in golf...
>
> I often wipe the cue ball between racks in short-rack games (9-ball,
> one-pocket, and 8-ball) for this reason. Perhaps it is mostly
> habit, but skids are probably the reason I started in the first
> place. I've noticed that many other players do this too.
Interesting. I have probably a dozen pool instructional books and tapes
and I don't recall one mentioning a thing called skid -- however it
seems everyone but me knows about it. Before reading it in Fels' book,
the only other time I heard the word was when Earl was complaining in an
IPT match but I figured he was just whining as usual.
lfigueroa
Lou Figueroa
lfigueroa
few inches. Not excessive spin.
Also, my experience is that it happens most often with follow shots shot
off the rail, with like 15, 20 degrees of cut.
Lou Figueroa
sooo confuzed
Dan White
news:MPG.228515354...@free.teranews.com...
>
> If you think of the two balls as gears while they are in contact, outside
causes the two
> gears to rotate in opposite directions in which case the contact induced
> throw is cancelled by the english induced throw in the opposite
> direction. With inside english, the contact induced throw adds to the
> english induced throw.
O...MY...GOD! John just invoked the "two gears" analogy with Ron Shepard.
I'm getting the popcorn.
> Interesting. I have probably a dozen pool instructional books and tapes
> and I don't recall one mentioning a thing called skid -- however it
> seems everyone but me knows about it.
Skid happens all the time, and it sucks. I must have happened to you, but
you just didn't recognize it.
dwhite
Dan White
so...but then I got a ball cleaner and it "dan't" happen nearly as much. :)
dwhite
"lfigueroa" <lfig...@att.net> wrote in message
news:ADMSj.152121$D_3.1...@bgtnsc05-news.ops.worldnet.att.net...
John Black
> "John Black" <jbl...@texas.net> wrote in message
> news:MPG.228515354...@free.teranews.com...
> >
> > If you think of the two balls as gears while they are in contact, outside
> causes the two
> > gears to rotate in opposite directions in which case the contact induced
> > throw is cancelled by the english induced throw in the opposite
> > direction. With inside english, the contact induced throw adds to the
> > english induced throw.
>
> O...MY...GOD! John just invoked the "two gears" analogy with Ron Shepard.
> I'm getting the popcorn.
Well, forget gears because I'm not wedded to the analogy. I believe I
remember a discussion where Ron said its not like gears, just sliding
surfaces and friction. Fine, but the point is there are two effects
during the contact time (I know Ron hates this too). In the case of
inside english, these effects add to produce a larger throw (vs. no
english). In the case of outside english these effects are in the
opposite direction and partially or completely cancel each other out.
The forward motion of the cue ball is pushing the object ball off line,
while the rotation of the cue ball is pulling the object ball back in
the opposite direction. (kind of like gears...)
> > Interesting. I have probably a dozen pool instructional books and tapes
> > and I don't recall one mentioning a thing called skid -- however it
> > seems everyone but me knows about it.
>
> Skid happens all the time, and it sucks. I must have happened to you, but
> you just didn't recognize it.
I'll recognize it now as the reason I miss a shot. :-)
Ron Shepard
"Dan White" <dwhi...@verizon.net> wrote:
> O...MY...GOD! John just invoked the "two gears" analogy with Ron Shepard.
> I'm getting the popcorn.
In this case, I think it is a good analogy, unlike the normal throw
situation. If the gear analogy really held for normal shots, then
all shots would look like skid shots. The fact that skid makes the
balls behave so unusual means that the gear analogy isn't a good way
to describe normal throw.
As far as skid adding and subtracting to normal throw, the
magnitudes are so different that you can ignore the normal throw
part. On a skid shot, the ball might throw off 30 or 40 degrees.
Normal throw would be about 10x smaller than that, 2-4 inches.
Skid might make you miss the pocket by 20 to 30 inches, normal throw
adds or subtracts 2 inches from that, which is in the noise.
I think when people say that "outside spin reduces the skid", they
aren't talking about the magnitude of the skid, they are really
talking about the frequency that it occurs. That is why I think a
statistical study is required to correlate the type of spin with the
frequency that skid occurs.
$.02 -Ron Shepard
Ed McCune
Dan White wrote:
> Skid happens all the time, and it sucks. I must have happened to you, but
> you just didn't recognize it.
>
> dwhite
>
>
Just change your underwear and act like nothing happened. No-one but you
need know about your skid problems.
Ed
John Black
ron-s...@NOSPAM.comcast.net says...
> In article <AGQSj.44$Jb2.17@trndny03>,
> "Dan White" <dwhi...@verizon.net> wrote:
>
> > O...MY...GOD! John just invoked the "two gears" analogy with Ron Shepard.
> > I'm getting the popcorn.
>
> In this case, I think it is a good analogy, unlike the normal throw
> situation. If the gear analogy really held for normal shots, then
> all shots would look like skid shots. The fact that skid makes the
> balls behave so unusual means that the gear analogy isn't a good way
> to describe normal throw.
>
> As far as skid adding and subtracting to normal throw, the
> magnitudes are so different that you can ignore the normal throw
> part. On a skid shot, the ball might throw off 30 or 40 degrees.
> Normal throw would be about 10x smaller than that, 2-4 inches.
> Skid might make you miss the pocket by 20 to 30 inches, normal throw
> adds or subtracts 2 inches from that, which is in the noise.
I knew skid was a different magnitude than throw but I didn't realize it
could be 10X. I guess the way to understand it is on a skid shot,
because there happens to be so much gunk between the balls, you can't
really consider it a ball to ball collision. I.e. the surfaces in
contact are not really the hard ball material. A completely different
surface will have different collision properties...
Dan White
news:fvgt8c$rfp$1...@registered.motzarella.org...
Ha! Maybe instead of "sucks" I should have said that skid stinks.
dwhite
Dan White
news:ron-shepard-A7FF...@comcast.dca.giganews.com...
> In article <AGQSj.44$Jb2.17@trndny03>,
> "Dan White" <dwhi...@verizon.net> wrote:
>
> > O...MY...GOD! John just invoked the "two gears" analogy with Ron
Shepard.
> > I'm getting the popcorn.
>
> In this case, I think it is a good analogy, unlike the normal throw
> situation.
Well then "shut my mouth"! as the saying goes.
dwhite
John Black
jbl...@texas.net says...
> I finally have an explanation that makes sense for why several good
> players advocate using a touch outside english whenever possible.
> George Fels explains it near the end of his book on straight pool.
Just a quick correction -- The book I was talking about is Play Your
Best Straight Pool by Phil Capelle, not George Fels. I somehow confused
it for another book I have by Fels that deals with straight pool.
Patrick Johnson
>> > Skid doesn't happen too often but when it does, its a run killer. It
>> > happens on lower speed shots with center ball or inside english. More
>> > with inside english than center ball. It shouldn't happen with outside
>> > which is why players try to use outside when possible especially with
>> > low speed shots.
Ron:
>> These things could be true, but I don't see any reason why they
>> should be. If you think that skid is caused by pieces of chalk that
>> get picked up from the tip or from the table over some period of
>> time and, due to random statistics, eventually find themselves
>> between the ball surfaces during a collision, than there would be
>> little or no relation to inside spin or any other spin with the
>> frequency of occurrence of skid.
John:
>Huh? My understanding is that skid is exaggerated throw.
I think you guys are using different definitions of "more". John
means more per shot and Ron means on more shots.
pj
chgo
John Black
patrick...@comcast.net says...
I think I was using it both ways at different times. In the paragraph
at the top I was using it as "more shots". But when it does occur, I
think it can be understood as a very exaggerated (i.e. more) throw due
to on this particular collision, you don't have the normal ball to ball
friction characteristics -- there is another material, chalk or gunk or
something, that has different enough friction characteristics to produce
much more throw than you could ever get with a standard ball to ball
collision.
Ron Shepard
John Black <jbl...@texas.net> wrote:
> I think I was using it both ways at different times. In the paragraph
> at the top I was using it as "more shots". But when it does occur, I
> think it can be understood as a very exaggerated (i.e. more) throw due
> to on this particular collision, you don't have the normal ball to ball
> friction characteristics -- there is another material, chalk or gunk or
> something, that has different enough friction characteristics to produce
> much more throw than you could ever get with a standard ball to ball
> collision.
Instead of waiting for those one-in-a-hundred shots where you get a
skid in order to try to understand this, you can artificially
generate situations the result in skid on almost every shot. You
can wet a spot on the object ball, say the size of a dime, and
spread cue chalk dust over the area. It sticks and forms sort of a
mud layer. You can generate the chalk dust by scraping a cube of
chalk with a penny. Place the object ball on the table so that the
spot of mud is right on the horizontal equator. When you hit that
spot with the cue ball, you get skid on almost every shot.
When you do this, it is clear that skid is a much larger effect in
magnitude than normal object ball throw. However, it is not clear
that the frequency changes with inside or outside spin combinations
or with topspin or draw. As I said before, a careful statistical
study would be required to demonstrate this relationship in the
"normal skid" case, but you can get an idea of what might happen in
this contrived mud-spot situation.
This is a messy experiment, so you should vacuum your table after
doing these shots for a few minutes. If you do it on a commercial
table in a public room, you should offer to clean the table for the
owner afterwards.
$.02 -Ron Shepard
Jal
wrote:
>... However, it is not clear
> that the frequency changes with inside or outside spin combinations
> or with topspin or draw. As I said before, a careful statistical
> study would be required to demonstrate this relationship in the
> "normal skid" case, but you can get an idea of what might happen in
> this contrived mud-spot situation.
I would think it would occur a little more often with inside english,
particularly with low inside english. A fresh chalk mark, which is
initially on the "equatorial plane", more or less travels with this
plane as it changes orientation, as the cueball picks up topspin The
shifting of the plane is shown here:
http://ww2.netnitco.net/users/gtech/EquatorialPlane.jpg
With low inside or outside, the plane passes through a horizontal
orientation, putting the fresh chalk mark in precarious positions as
it rotates around the ball.
Outside english is more immune, imo, because many cut shots with
outside english result in the cueball and object balls mutually
rolling across each other. In these cases, a surge in friction should
not produce any more throw since the rolling state is just arrived at
quicker. With inside english, the instances (types of shots) where the
balls end up rolling, are less.
Also, inside makes the friction force more horizontal. Outside,
combined with some topspin or draw, produces a more vertical
direction. If skid occurs, it's less damaging.
Jim
Ron Shepard
<6acdc6ed-f0f5-4433...@z72g2000hsb.googlegroups.com>,
Jal <j...@golden-tech.com> wrote:
> On May 12, 7:47 pm, Ron Shepard <ron-shep...@NOSPAM.comcast.net>
> wrote:
>
> >... However, it is not clear
> > that the frequency changes with inside or outside spin combinations
> > or with topspin or draw. As I said before, a careful statistical
> > study would be required to demonstrate this relationship in the
> > "normal skid" case, but you can get an idea of what might happen in
> > this contrived mud-spot situation.
>
> I would think it would occur a little more often with inside english,
> particularly with low inside english. A fresh chalk mark, which is
> initially on the "equatorial plane", more or less travels with this
> plane as it changes orientation, as the cueball picks up topspin The
> shifting of the plane is shown here:
>
> http://ww2.netnitco.net/users/gtech/EquatorialPlane.jpg
>
> With low inside or outside, the plane passes through a horizontal
> orientation, putting the fresh chalk mark in precarious positions as
> it rotates around the ball.
This is the common wisdom, but I am still skeptical that it is
correct. For example, with low-outside, it is possible for the
chalk spot to rotate only about 1/2 turn (depending on the cut
angle) to contact the object ball and cause skid. Yet, low-outside
is exactly what this common wisdom says is the best spin to use. It
is possible for low-inside spin to also cause skid, of course, but
the contact spot must rotate more than one full turn all the way
around the ball in order to get to the object-ball side and cause
skid.
Once natural roll (with sidespin) is achieved, then there is some
surface area at the top and bottom of the ball that never passes
through the equator. (In analogy to the fact that a spot on the
surface of the earth that is outside of the tropics never sees the
sun directly overhead.) If the chalk spot happens to end up there,
then the probability of it causing skid (on that shot) is zero.
$.02 -Ron Shepard
JakartaDean
>
> Once natural roll (with sidespin) is achieved, then there is some
> surface area at the top and bottom of the ball that never passes
> through the equator. (In analogy to the fact that a spot on the
> surface of the earth that is outside of the tropics never sees the
> sun directly overhead.) If the chalk spot happens to end up there,
> then the probability of it causing skid (on that shot) is zero.
>
> $.02 -Ron Shepard
In relation to your analogy, the rotation and revolution of the earth
are in the same plane, so an area above and below the equator never get
the sun straight overhead. In a ball with natural roll and sidespin,
the two axes of rotation are orthagonal, so I'm not sure the analogy
holds. In fact intuitively I'd say any given point could touch the
cloth or be on the equator.
Now I'm gonna have to dig out my Christmas ornaments again and start
rotating them to see what happens. Damn you, Ron ;-)
Dean
John Black
ron-s...@NOSPAM.comcast.net says...
> When you do this, it is clear that skid is a much larger effect in
> magnitude than normal object ball throw. However, it is not clear
> that the frequency changes with inside or outside spin combinations
> or with topspin or draw. As I said before, a careful statistical
> study would be required to demonstrate this relationship in the
> "normal skid" case
So many good players advocate a touch of outside on softly hit shots
that I would think this can be considered a study of sorts. Decent
sample size and *long term*, i.e. lifetimes worth of experience. Not
definitive but I think they would have eventually abandoned this idea if
they were getting as many skids doing it this way vs. center ball and
inside shots?
Ron Shepard
JakartaDean <deanb...@forteinc.com> wrote:
> Ron Shepard wrote:
> >
> > Once natural roll (with sidespin) is achieved, then there is some
> > surface area at the top and bottom of the ball that never passes
> > through the equator. (In analogy to the fact that a spot on the
> > surface of the earth that is outside of the tropics never sees the
> > sun directly overhead.) If the chalk spot happens to end up there,
> > then the probability of it causing skid (on that shot) is zero.
>
> In relation to your analogy, the rotation and revolution of the earth
> are in the same plane,
No, they are 23 degrees different.
> so an area above and below the equator never get
> the sun straight overhead. In a ball with natural roll and sidespin,
> the two axes of rotation are orthagonal,
The spin axis of the ball is somewhere between horizontal and
vertical. It is the vector sum of the vertical sidespin axis and
the horizontal forward roll axis.
> so I'm not sure the analogy
> holds. In fact intuitively I'd say any given point could touch the
> cloth or be on the equator.
>
> Now I'm gonna have to dig out my Christmas ornaments again and start
> rotating them to see what happens. Damn you, Ron ;-)
Here is one way to visualize this. When the ball achieves natural
roll with sidespin, the poles of the ball are fixed (almost) and the
ball just spins around that axis. The points on the ball that touch
the surface all lie on a circle that is parallel to the rotational
equator and perpendicular to the axis. The location of that circle
(i.e. the latitude) depends on the axis tilt. If there is just a
little bit of sidespin, then the axis is almost horizontal, the
equator is almost vertical, and the latitude of contact points is
almost vertical; if there is a lot of sidespin, the axis is almost
vertical, the equator is almost horizontal, and the latitude of
contact points is almost horizontal. Think of a cylinder (like a
soup can, or an oil drum) embedded within the ball, with the edges
of the cylinder touching the surface of the ball at the latitude of
contact points. The rolling ball is like tilting the cylinder over
on its edge to achieve perfect balance and rolling it along the
cloth. A short fat cylinder corresponds to a little sidespin, a
tall skinny cylinder corresponds to a lot of sidespin.
Of course, the tilt axis changes a little over time as the ball
rolls to a stop, so the above picture is just an approximation, but
it gives a good idea at least for short intervals of time about how
the ball behaves, and it is easy to imagine how spots on the surface
of the ball that are close enough to the poles would not cross the
horizontal equator line. If they don't cross the equator line, then
they would never be part of the ball-ball contact and there is no
chance of such a spot causing skid.
$.02 -Ron Shepard
Ron Shepard
John Black <jbl...@texas.net> wrote:
> In article <ron-shepard-82FC...@comcast.dca.giganews.com>,
> ron-s...@NOSPAM.comcast.net says...
> > When you do this, it is clear that skid is a much larger effect in
> > magnitude than normal object ball throw. However, it is not clear
> > that the frequency changes with inside or outside spin combinations
> > or with topspin or draw. As I said before, a careful statistical
> > study would be required to demonstrate this relationship in the
> > "normal skid" case
>
> So many good players advocate a touch of outside on softly hit shots
> that I would think this can be considered a study of sorts. Decent
> sample size and *long term*, i.e. lifetimes worth of experience.
Yet, there are so many counter examples that demonstrate the
opposite, it is easy to understand my skepticism. As I said before,
low-outside would allow the chalk spot on the cue ball to rotate
around in 1/2 a ball turn to cause skid, but low inside cannot do
this, so this particular picture is exactly the opposite of common
wisdom.
> Not
> definitive but I think they would have eventually abandoned this idea if
> they were getting as many skids doing it this way vs. center ball and
> inside shots?
These are rare events (somewhere in the 1/100 to 1/1000 range I
would guess), and I think it is easy to be mislead/confused/deceived
about relative probabilities of rare events. This is, after all,
what keeps lottos and casinos in business.
$.02 -Ron Shepard
Jal
wrote:
>
> This is the common wisdom, but I am still skeptical that it is
> correct. For example, with low-outside, it is possible for the
> chalk spot to rotate only about 1/2 turn (depending on the cut
> angle) to contact the object ball and cause skid. Yet, low-outside
> is exactly what this common wisdom says is the best spin to use. It
> is possible for low-inside spin to also cause skid, of course, but
> the contact spot must rotate more than one full turn all the way
> around the ball in order to get to the object-ball side and cause
> skid.
Yes, that's another point to ponder. Also, I suspect that outside is
used much more than inside, so there may very well be more occurrences
of skid with it. But on a per use basis (inside vs outside), I still
think inside is more susceptible. Where normal friction would cause
the balls to roll on each other, abnormally large friction should not
change the throw angle, ie, you get "silent skid". (I think Rachael
Carson wrote a book about it.) And there are many more situations
where roll occurs with normal friction using outside english.
> Once natural roll (with sidespin) is achieved, then there is some
> surface area at the top and bottom of the ball that never passes
> through the equator. (In analogy to the fact that a spot on the
> surface of the earth that is outside of the tropics never sees the
> sun directly overhead.) If the chalk spot happens to end up there,
> then the probability of it causing skid (on that shot) is zero.
But I don't think the chalk mark typically ends up there (with a few
exceptions). It always starts on the equator (the one perpendicular to
the spin axis), and generally remains there, more or less. By "there",
I mean on the spin axis' equator, regardless of how the axis changes
direction. The torque exerted by the cloth is not enough to move it to
higher or lower latitudes, so to speak, except where you have a high
torque to spin ratio (ie, slight spin). So the chalk mark usually
continues to cross the "ecliptic" (using your analogy) as it moves
around the ball. On a cut shot, it is only dangerous as the spin
equator passes through the "ecliptic". No?
Jim
lfigueroa
Lou Figueroa
lfigueroa
http://CueTable.com/P/?@4AImg4PYVf4UImg3Ucho4kYVf4kLXc2uDCG@
or
http://CueTable.com/P/?@4AUKr1PLCH4UUKr4Uchx1kLCH4kTtb3uCUL@
IOW, a shot at about that distance, with about that angle, that I have
to shoot with follow, I really worry about skid, so I always shoot those
with a touch of outside.
Lou Figueroa
no study
just a feeling
John Black
lfig...@att.net says...
> The only thing I know is that when I see a shot like this:
>
> http://CueTable.com/P/?@4AImg4PYVf4UImg3Ucho4kYVf4kLXc2uDCG@
>
> or
>
> http://CueTable.com/P/?@4AUKr1PLCH4UUKr4Uchx1kLCH4kTtb3uCUL@
>
> IOW, a shot at about that distance, with about that angle, that I have
> to shoot with follow, I really worry about skid, so I always shoot those
> with a touch of outside.
>
> Lou Figueroa
> no study
> just a feeling
The feeling is caused by a lifetime of experience. Its the subconscious
voice in the back of your head that remembers all (or in your case the
drunk in the back of the room...)
John Black
ron-s...@NOSPAM.comcast.net says...
> In article <MPG.229365932...@free.teranews.com>,
> John Black <jbl...@texas.net> wrote:
>
> > In article <ron-shepard-82FC...@comcast.dca.giganews.com>,
> > ron-s...@NOSPAM.comcast.net says...
> > > When you do this, it is clear that skid is a much larger effect in
> > > magnitude than normal object ball throw. However, it is not clear
> > > that the frequency changes with inside or outside spin combinations
> > > or with topspin or draw. As I said before, a careful statistical
> > > study would be required to demonstrate this relationship in the
> > > "normal skid" case
> >
> > So many good players advocate a touch of outside on softly hit shots
> > that I would think this can be considered a study of sorts. Decent
> > sample size and *long term*, i.e. lifetimes worth of experience.
>
> Yet, there are so many counter examples that demonstrate the
> opposite, it is easy to understand my skepticism. As I said before,
> low-outside would allow the chalk spot on the cue ball to rotate
> around in 1/2 a ball turn to cause skid, but low inside cannot do
> this, so this particular picture is exactly the opposite of common
> wisdom.
But you are talking about the skid being caused by chalk applied to the
cue ball on the same shot as the skid. I think that probably represents
a low percentage of all skids. How low, I don't know but the
recommendation is to wipe down the cue ball every game or couple of
games. If skids happened because of chalk applied on the same shot,
then that recommendation is not worth very much.
> > Not
> > definitive but I think they would have eventually abandoned this idea if
> > they were getting as many skids doing it this way vs. center ball and
> > inside shots?
>
> These are rare events (somewhere in the 1/100 to 1/1000 range I
> would guess), and I think it is easy to be mislead/confused/deceived
> about relative probabilities of rare events. This is, after all,
> what keeps lottos and casinos in business.
No disagreement.
JakartaDean
> In article <x7cWj.34556$dq6....@en-nntp-09.dc1.easynews.com>,
> JakartaDean <deanb...@forteinc.com> wrote:
>
>> Ron Shepard wrote:
>>> Once natural roll (with sidespin) is achieved, then there is some
>>> surface area at the top and bottom of the ball that never passes
>>> through the equator. (In analogy to the fact that a spot on the
>>> surface of the earth that is outside of the tropics never sees the
>>> sun directly overhead.) If the chalk spot happens to end up there,
>>> then the probability of it causing skid (on that shot) is zero.
>> In relation to your analogy, the rotation and revolution of the earth
>> are in the same plane,
>
> No, they are 23 degrees different.
I knew that (well, forgot the exact number) but was simplifying. Now
that I've read your explanation, I do understand and that was a critical
omission. Thanks again Ron.
Dean
Ron Shepard
<FYkWj.330563$cQ1....@bgtnsc04-news.ops.worldnet.att.net>,
lfigueroa <lfig...@att.net> wrote:
> The only thing I know is that when I see a shot like this:
>
> http://CueTable.com/P/?@4AImg4PYVf4UImg3Ucho4kYVf4kLXc2uDCG@
>
> or
>
> http://CueTable.com/P/?@4AUKr1PLCH4UUKr4Uchx1kLCH4kTtb3uCUL@
>
> IOW, a shot at about that distance, with about that angle, that I have
> to shoot with follow, I really worry about skid, so I always shoot those
> with a touch of outside.
These are both shots that, if you shoot them with straight topspin,
there is absolutely no chance at all that the chalk spot will rotate
around to the ball-ball contact spot. It is only sidespin that the
chalk spot might spin around to that side of the ball.
I'm not saying that you should or shouldn't use sidespin on those
shots. I'm just pointing out that the "common wisdom" about using
outside sidespin to reduce the frequency of skid is not consistent
with the mechanism by which skid occurs. There is a disconnect
here. I don't know the answers to all of this, but there is a
disconnect of some kind happening here. That means that either the
"common wisdom" is wrong, or the mechanism by which skid occurs is
wrong. My feeling is that it is probably the "common wisdom" that
is wrong. Until someone does a careful and accurate statistical
study that shows the relation between skid and various spins on the
cue ball, I'm skeptical of the "common wisdom" that outside sidespin
reduces the frequency of the occurrence of skid.
$.02 -Ron Shepard
Ron Shepard
John Black <jbl...@texas.net> wrote:
> But you are talking about the skid being caused by chalk applied to the
> cue ball on the same shot as the skid.
Yes, but chalk spots from previous shots would likely be random and
could only be treated statistically (i.e. size of the spot, vs.
total surface area of the ball, vs. the size of the ball-ball
contact spot).
> I think that probably represents
> a low percentage of all skids.
Perhaps, I don't know. That is why I think a careful statistical
analysis of this would be useful.
> How low, I don't know but the
> recommendation is to wipe down the cue ball every game or couple of
> games. If skids happened because of chalk applied on the same shot,
> then that recommendation is not worth very much.
As I said before, I do clean the cue ball between racks (and after
fouls, etc.). However, I don't really know if it helps reduce skid,
but I figure it can't hurt.
$.02 -Ron Shepard
Jal
wrote:
> I'm not saying that you should or shouldn't use sidespin on those
> shots. I'm just pointing out that the "common wisdom" about using
> outside sidespin to reduce the frequency of skid is not consistent
> with the mechanism by which skid occurs. There is a disconnect
> here. I don't know the answers to all of this, but there is a
> disconnect of some kind happening here. That means that either the
> "common wisdom" is wrong, or the mechanism by which skid occurs is
> wrong. My feeling is that it is probably the "common wisdom" that
> is wrong. Until someone does a careful and accurate statistical
> study that shows the relation between skid and various spins on the
> cue ball, I'm skeptical of the "common wisdom" that outside sidespin
> reduces the frequency of the occurrence of skid.
The common wisdom isn't wrong. See above.
One seventh of the 'change' in relative surface speed between the
balls during impact becomes the object ball's throw velocity in the
direction of the friction force (not necessarily horizontal). Another
seventh is added (vectorally) to the cueball's tangential speed
component. The remaining 5/7'ths is parceled out equally as spin
components on both balls. When the change in relative surface speed
equals the initial surface speed (ie, it's exhausted), the balls then
roll across each other. In these cases, it doesn't matter how great
the friction; there is only so much surface speed to be taken up. The
OB's throw velocity component is then immune to any increase in the
coefficient of friction. This happens much more often when outside is
used. Outside reduces the initial relative surface speed so that
rolling can take place.
It also helps to alleviate the effects of skid when draw or follow is
present. The right amount makes the friction force nearly vertical,
as also mentioned above.
Jim
Thyme3421
ignored this thread a while back.
-Duane Edwards << ignores a lot of things
"Good enough to win money, not good enough to make it."
http://diamondstopockets.blogspot.com
_______________________________________________________________________
RecGroups : the community-oriented newsreader : www.recgroups.com
lfigueroa
Lou Figueroa
he's still
back there
lfigueroa
your last shot. It's especially like that if you or the guy you're
playing has just roughed up their tip.
Lou Figueroa
Thyme3421
thread again. I tend to drop into a slump when I start thinking about the
shots too much... scientifically sorta thinking, ruins my game. (reference
the object ball curve thread, followed by 2 month slump.)
So I'm outta this thread! Good luck kids, and I'll report in when I see
some threads that I'm willing to risk.
-Duane Edwards << thought EVERYONE should know
"Good enough to win money, not good enough to make it."
http://diamondstopockets.blogspot.com