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Author Topic: Questions about Virtual Mass Bias  (Read 1941 times)

1-2-3

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Questions about Virtual Mass Bias
« on: August 23, 2006, 02:05:09 PM »
I just ordered an Immortal Pearl from Buddies and the specifications listed for the ball were 3 ounces of top weight and a 3-4 inch pin - 15 lbs.  

How can the pin be 3-4 inches when the drilling instructions say you must measure and mark the Virtual Mass Bias?  I do understand the 3-4 inch pin is measured from the CG.

Is the CG location even marked on the AMB line?

Why doesn’t Visionary mark the Virtual Mass Bias?

Wouldn’t the pin be in the same location on every ball because the locator pin and the flip cap pin are in the same location every time?

I’ve read in other posts that balls with asymmetrical cores, the CG doesn’t factor in as much as the mass bias location, or in this case the virtual mass bias.


My plan for this ball is to place the pin at flip pin location B and the virtual mass bias location #3.

I’m having trouble with the midlane area and the ball reading it too much. (Ball hooking too much in the midlane.)

I thought this ball with the pearl cover would get me through the midlane and with its dynamic core still have some power while using this mild pin placement. (Not leave a bunch of ten pins)

If anyone has any thing to pass along about this please respond.  The ball won’t be in for a couple of days and if I’m way out in left field let me know.

Thanks for the help.

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shelley

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Re: Questions about Virtual Mass Bias
« Reply #1 on: August 24, 2006, 12:05:15 AM »
quote:
How can the pin be 3-4 inches when the drilling instructions say you must measure and mark the Virtual Mass Bias?  I do understand the 3-4 inch pin is measured from the CG.

Is the CG location even marked on the AMB line?

Why doesn’t Visionary mark the Virtual Mass Bias?

Wouldn’t the pin be in the same location on every ball because the locator pin and the flip cap pin are in the same location every time?


The CG is simply the heaviest spot on the ball.  Has nothing to do with mass bias or anything like that.  On a symmetric cored ball, you can draw a line 6 3/4" from the pin through the CG to find the "mass bias".  Then you could lay the ball out like a normal MB ball and never have to think about a ball being symmetric or asymmetric.

The way I understand it (and I believe this is what Visionary's said) is that the Anti-MB locator pin is a manufacturing artifact the same way the pin is.  Brunswick's Zone balls, current Morich balls, and some Lane 1 balls are the same way.  The locator pin is actually a plastic pin that goes from the surface to the core, just like the normal pin is (in the case of the normal pin, it's used to hold the core in place during manufacturing).  That way, asymmetric balls don't have to be spun individually to verify the location of the PSA.  I believe Track, Storm, RG, and DT have to spin theirs to ensure the PSA marker is accurate.

Because the AMB pin is an actual plastic pin that reaches to the surface, it's always correct and there's no need to mark the AMB or VMB.  Marking the VMB would be an extra step in the manufacturing process, increasing costs.  Alternatively, leaving out the locator pin would require spinning each ball to find the MB, also adding to the cost.

SH
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1-2-3

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Re: Questions about Virtual Mass Bias
« Reply #2 on: August 24, 2006, 09:44:01 PM »
Shelley, thanks for the explaination of mass bias and the two locator pins.

So with this process of ball construction, using two pins, the concept of a pin-in or pin-out ball is meaningless because the core is always in the exact same position within the shell of the ball?

I selected this ball because I seem to do better with pin-out balls.

In the past when I'd have a ball with a short pin-out, less than 3 inches, my driller has told me he doesn't like moving the pin up which in turn would move the CG up, because in his experience if the CG is much outside of the grip center the ball reaction can be unpredictable.

That shouldn't be a problem with this type of ball because all you need is the pin and the mass bias position?

Thanks again for the time to explain it to me.
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shelley

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Re: Questions about Virtual Mass Bias
« Reply #3 on: August 24, 2006, 09:55:29 PM »
quote:
So with this process of ball construction, using two pins, the concept of a pin-in or pin-out ball is meaningless because the core is always in the exact same position within the shell of the ball?


Not necessarily.  The amount of shift required to create 2", 3", 4", or even 5" pin distances is small fractions of an inch.  64ths or 32nds of an inch.  You can easily nudge something that's nominally rigid that much without really trying.

quote:
That shouldn't be a problem with this type of ball because all you need is the pin and the mass bias position?


For balls with a sufficiently strong PSA (mass bias, anti-mass bias, asymmetric, whatever you want to call it), you would pretty much ignore the CG when laying out the ball anyway.  It has minimal influence on ball reaction, and the only thing you really use it for is to determine whether you need a weight hole (that can be an important consideration, especially if the CG is far off the pin-MB line).

That's something I really like about asymmetric balls.  They give you all the drilling options you would want regardless of the actual pin length.

SH
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