Any section taken from a circle or oval is considered a parabola. As one example on the inter-web put it, "when a kid kicks a soccer ball, the ball goes up then comes down, following the path of a parabola." Shafts with a curved taper, exactly the way SW is done, is a parabolic taper. If you take a SW shaft and continue the line, it will eventually come complete to intersect with itself.
Taper of the butt portion?
- Thread starter cue fix
- Start date
Any section taken from a circle or oval is considered a parabola. As one example on the inter-web put it, "when a kid kicks a soccer ball, the ball goes up then comes down, following the path of a parabola." Shafts with a curved taper, exactly the way SW is done, is a parabolic taper. If you take a SW shaft and continue the line, it will eventually come complete to intersect with itself.
If it does not conform to the actual accurate definition of a parabola it is not parabolic.
I am simply saying that in order to call a curve parabolic it must conform the the defination of a parabola. That's all!!
That is indeed a true parabola. The same would be true if you squished the center and extended the legs to a very flat-ish bow rather than the exaggerated curve arc shown. If you wish to go full on nerd and begin policing tapers so you can discount or confirm them as true parabolas, then have at it. For me, when I hear somebody use the term "parabolic taper", I understand it means a curved taper.
I'm confused.Are you complimenting me or gloating about yourself? :thumbup:
Yes...
Dale
I think you will find that what you described as a parabola is actually defined as an arc
rather than a parabola.
But it gets worse... much worse.
Checking on the discussion of parabolic tapers, I came across an old thread where someone
explained that parabolic taper didn't mean a shaft that looked like a side of the Eiffel Tower,
but rather a profile that was generated using a PARABOLIC Equation.
Now it has been about 104 years since I stumbled through courses in Differential Equations,
but it seems to me that typically one might generate a Parabolic Equation from the data in a shaft profile,
but not the other way round. I considered soliciting some advanced Maths genius like
Dr. Dave or Bob Jewett to chime in but set the idea aside... perhaps it is time to bring in the large guns
Dale
That's actually pretty accurate, because I am not describing the parabola in whole, but only a section taken from one half of a parabola. Or at least that's what I'm trying to articulate. My words aren't saying what my mind is seeing, and it's frustrating
A Parabola... is a curve formed by the set of points in a plane that are all equally distant from both a given line (called the directrix) and a given point (called the focus) that is not on the line.
qbuilder said:
The bottom line is "parabolic" sounds cool. It was used to describe a pool shaft taper at some point and caught on. Now it is a buzz word. Cuemakers who use the term to describe a shaft taper don't give a damn whether they use the term correctly or not.
If I showed three curves on a graph; one parabolic, one hyperbolic, and one logarithmic, cuemakers would say they are all parabolic. A piece of an ellipse or circle is not parabolic.
I personally feel like most curved shaft tapers resemble logarithmic curves more than parabolic curves. I used logarithmic equations for the starting shaft tapers (that are meant to be tweaked) in CueCut. I bet they look "parabolic".
If I showed three curves on a graph; one parabolic, one hyperbolic, and one logarithmic, cuemakers would say they are all parabolic. A piece of an ellipse or circle is not parabolic.
I personally feel like most curved shaft tapers resemble logarithmic curves more than parabolic curves. I used logarithmic equations for the starting shaft tapers (that are meant to be tweaked) in CueCut. I bet they look "parabolic".
Technically, maybe. Partial parabola is likely the best descriptive, as it's one section of one half of a full parabola. Calling it a parabolic taper has always made sense to me because if you mirror one, or simply follow it to infinity, it creates a complete and true parabola. The same is not true for a pro taper because a pro taper has a length of straight on what would be the directrix, which a parabola does not. The parabolic tapers have a continuous, progressively increasing curve.
To change or add terms would only confuse an already confusing topic, IMO. While technically a half or partial parabola is not a parabola, it is the term we use & most us understand what it means.
Take the graphed parabola Todd posted, and split it in half. Does the line not have an uncanny resemblance to a Kersenbrock or SW shaft taper? So would it be safe to say that Kersenbrock likely had fair reason for calling it a parabolic taper? It wasn't a buzzword but a description of shape. Nowadays, you're correct it has become a buzzword to describe any curved taper. Our industry is full of incorrect terminology.
I have no doubt that someone somewhere at some point has made a shaft taper bar using a parabolic equation (whether for the entirety of the taper bar or only the curved section) and used it to cut their shafts. Maybe Kersenbrock did. I'm not saying it has never been done, I'm saying every curved shaft referred to as "parabolic" isn't. I think this to be particularly true if the user of the taper isn't the author and manufacturer of the taper bar (or GCode program) producing the shaft.
Your description of the curve going out to infinity is more descriptive of a hyperbola than a parabola. If the very first person who coined the term parabolic for pool shafts would have used hyperbolic instead, would all curved pool shafts be hyperbolic? Try this. Find a picture of a sine curve and chop out just a top or bottom hump. It looks a LOT like a parabola, particularly if you tweak the amplitude/scale perspective. Split it in half and you have a taper that looks a lot like the "parabolic" shaft taper. Some shaft tapers could probably be called trigonometric and be just as accurately named.
Let's assume you make a living as a mathematician and frequent mathematical forums. You also build cues for fun. One of your fellow mathematicians claims pool shafts are all made of ramin wood because some have been and to them they all look the same. You might want to interject and say not all pool shafts are ramin wood. If you went into all sorts of details of how maple is far from ramin wood in order to educate them, they might accuse you of going full on nerd and want to cover their ears. :wink:
Hi,
I have a compound taper with a very slight sweeping or curve to the contour from the butt cap to the A joint. Parabolic taper is a discription like xerox or Kleenex respectively.
I do this because I designed my A Joint dia at 1.006 with finish.
So if the butt end is 1.245 to 1.006 at the A Joint my cue is slightly thinner than most. The taper from the A Joint to the nose is conical to .854 with finish.
When straight edge is held next to the cue the air gap annulus is barely seen over the 24" profile. When rolled on the table it is basically a non issue visually.
I believe this configuration gives the cue a special feedback with a slightly thinner grip.
Of course that feedback must go hand in hand with a correct shaft taper that has a perfect flex point geometry.
JMO,
Rick
I have a compound taper with a very slight sweeping or curve to the contour from the butt cap to the A joint. Parabolic taper is a discription like xerox or Kleenex respectively.
I do this because I designed my A Joint dia at 1.006 with finish.
So if the butt end is 1.245 to 1.006 at the A Joint my cue is slightly thinner than most. The taper from the A Joint to the nose is conical to .854 with finish.
When straight edge is held next to the cue the air gap annulus is barely seen over the 24" profile. When rolled on the table it is basically a non issue visually.
I believe this configuration gives the cue a special feedback with a slightly thinner grip.
Of course that feedback must go hand in hand with a correct shaft taper that has a perfect flex point geometry.
JMO,
Rick
Last edited:
ONLY amongst cuemakers, which makes such a statement inherently incorrect.
That's actually pretty accurate, because I am not describing the parabola in whole, but only a section taken from one half of a parabola. Or at least that's what I'm trying to articulate. My words aren't saying what my mind is seeing, and it's frustrating
I know the feeling...
Dale
JC
Coos Cues
Hello again. It seems as my post has caused some difference issues, which was not my intent. I was curious as to the type of taper was on my cue as I have had several old cues with this taper and as one cue maker mentioned, some people tell you your cue is warped because the joint doesn't touch the surface like most cues. The cues forearm is only 10" from wrap to end of the cue. the wrap is 15" and from the butt sleeve up the wrap for 11" it decreases at .01" per inch, then the last 4" of the wrap it decreases .03" per inch. The cue is an old Martin. I appreciate the insight of those who responded to my post and hope that the differences can be resolved.