what is a parabolic taper

vasilios said:
Take a arc segment out of any circle add a focus point and you have a parabola.A 29 inch segment with 60 foot radius can be called a parabola.

in simple G-code
G01 X0 Y0
G02 X29 Y0 R720.00
instant parabola

compound tapers are better for shafts to hit pool balls.
parabola works good for mirrors focusing light.

Maybe a parabolic shaft will help you see the balls better.

bill
Click to expand...

vasilios said:
I did not say the term focus point is in the g-code language.you can take a arc and determine the parabolic focal point.the center point end of the radius is not the parabolic focal point.

bill
Click to expand...

I don't quite understand what you are saying... Your first post to me says that its possible to program a parabola with G-code. However, the example you gave is for an arc, with given start point, end point, and radius. It is not a parabola. Am I interpreting you correctly? Thanks.
 
iusedtoberich said:
No offense taken, I have enjoyed this thread. But the question, regardless of if you use a manual taper bar, or a cnc, or a knife to whittle the shaft:

How do you know your taper is parabolic? A taper with no straight sections does not mean its parabolic. That's the crux of the question, IMO.
Click to expand...

The more correct term for my taper would be a spline. Where the curve is constantly changing, rather than being a group of lines or arcs. You are right in that I cant prove the math of it being a parabola.
 
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Traditionally, 40 years ago, a pro taper was a constant diameter for about 13" back from the ferrule then it opened up. These were fairly rapidly modified to a modified pro-taper which gradually opened up from the ferrule back about 12-16" then opened more quickly back to the joint.
 
iusedtoberich said:
This makes the most sense to me. It would be relatively easy to program a true parabolic curve by using a spreadsheet to generate the x,y values for short linear moves. You can also draw a parabola in a CAD program, and then use your CAM program to generate the G-code from the geometry. I never got into CAM (I stopped at hand-coding G-code), but my understanding of CAM packages is that they convert all the geometry from your CAD program into short linear moves.

So the question remains, does the cue maker who uses the term "parabolic taper" do any of the above, or are they very loose in their use of the word parabolic to include a taper with zero straight sections?
Click to expand...

Royce and usedtobe: why would you ever even consider hand coding the
program to CNN anything, no matter how simple?

1. CAD draw a shape.
2. CAM the drawing.
3. process the drawing file to CAM generate the G-Code.
4. Load the G-Code file.
5. Hit START button.
6. Go to lunch.

The big advantage:

next Tuesday, when you want to change something by 17 1/2
thousandths, you don't ever need to 'touch' the code.

Dale(automator terminator)
 
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pdcue said:
Royce and usedtobe: why would you ever even consider hand coding the
program to CNN anything, no matter how simple?

1. CAD draw a shape.
2. CAM the drawing.
3. process the drawing file to CAM generate the G-Code.
4. Load the G-Code file.
5. Hit START button.
6. Go to lunch.

The big advantage:

next Tuesday, when you want to change something by 17 1/2
thousandths, you don't ever need to 'touch' the code.

Dale(automator terminator)
Click to expand...

For me, it was a matter of what I had available at the time. I learned on a Bridgeport vertical machining center at school that had a G-Code manual with it. It just sat there with no one using it, so I had it to myself for several months. I went through page by page of its G-code manual, and made several hand written programs to learn the in and outs of coding, lead in and lead outs, turning cutter compensation on and off, dwell drilling, tool loading and offsets, etc. I think it was a good experience, and I got lucky and never crashed! lol

I would actually like to learn MasterCAM now, (someday), and think understanding the hand coding from my past will be a benefit in understanding how a CAM package would work.
 
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pdcue said:
Royce and usedtobe: why would you ever even consider hand coding the
program to CNN anything, no matter how simple?

1. CAD draw a shape.
2. CAM the drawing.
3. process the drawing file to CAM generate the G-Code.
4. Load the G-Code file.
5. Hit START button.
6. Go to lunch.

The big advantage:

next Tuesday, when you want to change something by 17 1/2
thousandths, you don't ever need to 'touch' the code.

Dale(automator terminator)
Click to expand...

Dale

Things are a little different for me than for most.

I have several different machines with different safe zones, leads, cut direction, etc. Some cut 4 at a time, some 2, and some 1.

When I change a taper, it's not one taper, it's 4 tapers. I can throw my numbers into a spreadsheet and post out my text files faster than I can draw the geometry in a CAD program. Not to mention change post processors for the different machines and post out each of the tapers.

What CAD/CAM are you using? I have AutoCad and BobCad. Obviously, AutoCad doesn't have a Cam function, but I use BobCad quite often for other things. I have not, however, found an easy way to post multiple passes to cut a profile. When we cut shafts, we cut down and back for each turn on the machine, or taper. When drawing a profile, and posting code to it, I don't really see an easy way to post code to go down and back. If there's an easy solution, I'd love to know. I'm all for making things easier!

Keep in mind that we make thousands of passes each week, and my programs have to be extremely efficient. Seconds add up to dollars real fast.
 
Parabolic taper

What research I have done .

And I still don't understand how any shaft could have a parabolic taper when the main example of what a parabolic taper is on a set of leaf spring .


I did see that there is parabolic tapered drill bits .

Before my opinion was in order for anything had a parabolic taper it had to be bent like leaf springs .
But because they make parabolic tapered drill bits my opinion might not be correct.

I have to wonder if this is not something some cue maker just decided to call the taper he puts on the shafts he makes for his cues or if the shaft actually has a real parabolic taper.

There is also parabolic dish as in like a radar dish .

I under parabolic taper on leaf springs .

I don't understand parabolic taper on a cue shaft and a drill bit..

Every time I here someone say parabolic taper on a pool cue shaft I have to wonder if they really know that as a fact or just repeating what they have heard ..

If I am correct the parabolic taper has also been called a European taper ..
 
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mortuarymike-nv said:
What research I have done .

And I still don't understand how any shaft could have a parabolic taper when the main example of what a parabolic taper is on a set of leaf spring .


I did see that there is parabolic tapered drill bits .

Before my opinion was in order for anything had a parabolic taper it had to be bent like leaf springs .
But because they make parabolic tapered drill bits my opinion might not be correct.

I have to wonder if this is not something some cue maker just decided to call the taper he puts on the shafts he makes for his cues or if the shaft actually has a real parabolic taper.

There is also parabolic dish as in like a radar dish .

I under parabolic taper on leaf springs .

I don't understand parabolic taper on a cue shaft and a drill bit..

Every time I here someone say parabolic taper on a pool cue shaft I have to wonder if they really know that as a fact or just repeating what they have heard ..

If I am correct the parabolic taper has also been called a European taper ..
Click to expand...
IF it has linear angle, how can it be "parabolic" ?
 

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I have a custom shaft for my Titlist conversion cue and a Predator 314-2 FAT shaft that was customized for it from a partial blank.

The custom regular shaft has a "modified Predator parabolic taper" according to the maker. It feels "different", for lack of a better word. You can feel that it isn't "straight" taper all the way down, if that explains it a bit. It seems to be kind of "cork screw" like it get bigger and smaller in places.
 
A parabolic taper on a shaft is:

A taper that starts getting thicker immediately behind the ferrule
and keeps getting thicker all the way to the joint. Furthermore the
rate of growth keeps increasing all the way down the shaft. For
example the measurements taken at 1", 2", 3", 4", 5", 6" from the
tip of a 13.00mm shaft could be something like:

13.01mm (+0.01mm), 13.03mm(+0.02mm), 13.06mm(+0.03mm), 13.10mm(+0.04mm), 13.15mm(+0.05mm), 13.22mm(+0.07mm) and so on.

gr. Dave
 
mortuarymike-nv said:
What research I have done .

And I still don't understand how any shaft could have a parabolic taper when the main example of what a parabolic taper is on a set of leaf spring .


I did see that there is parabolic tapered drill bits .

Before my opinion was in order for anything had a parabolic taper it had to be bent like leaf springs .
But because they make parabolic tapered drill bits my opinion might not be correct.

I have to wonder if this is not something some cue maker just decided to call the taper he puts on the shafts he makes for his cues or if the shaft actually has a real parabolic taper.

There is also parabolic dish as in like a radar dish .

I under parabolic taper on leaf springs .

I don't understand parabolic taper on a cue shaft and a drill bit..

Every time I here someone say parabolic taper on a pool cue shaft I have to wonder if they really know that as a fact or just repeating what they have heard ..

If I am correct the parabolic taper has also been called a European taper ..
Click to expand...

European taper is just the American way of saying conical, which is not parabolic.

IMHO - leaf springs are more hyperbolic than parabolic, but geometry was a long time ago.

To perhaps help you visualize the concept of a parabolic taper shaft, imagine the
Eiffel Tower cut in half lengthwise.(heightwise?)

Dale
 
pdcue said:
European taper is just the American way of saying conical, which is not parabolic.

IMHO - leaf springs are more hyperbolic than parabolic, but geometry was a long time ago.

To perhaps help you visualize the concept of a parabolic taper shaft, imagine the
Eiffel Tower cut in half lengthwise.(heightwise?)

Dale
Click to expand...



Nice example.

image002.jpg
 
Chopdoc said:
Nice link.

That is simple, and how I have understood it for many years.


.
Click to expand...

And I just choose a random part of the parabola to use because it made it easy to give coefficients that would work easily for everyone. Obviously (or maybe not...I'm just assuming this is correct) you wouldn't use that part of the parabola for a shaft taper or you would loose the property that parabolas can transmit load in pure compression. Of course, this is a little like saying that nuclear waste is stored in drums sitting on wooden pallets, and our cue shafts are made of wood, therefore cues are made using nuclear technology. :rolleyes: But math/physics aside, it's generally easy to find a section of some particular parabola that will fit some gentle curve.

It's similar to using a French curve. Those are generally sections of Euler Spirals, which are actually very loosely related to parabolas (cubic parabola, specifically). If you fiddle around enough with the numbers, you can almost anything match anything else, and call it whatever strikes your fancy. :)
 
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