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Author Topic: What does ‘Spin time’ mean in an asymmetric ball?  (Read 4025 times)

CharlieBrown

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What does ‘Spin time’ mean in an asymmetric ball?
« on: October 20, 2008, 02:38:04 AM »
Thanks.
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MTD300

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #1 on: October 20, 2008, 10:40:26 AM »
Hey mate,

I'm pretty sure its the time it takes for a ball to go from its unstable posistion to its stable posistion on a determinator. Lower rg cores will have a much quicker spin time and higher rg cores. I think its that anyway.
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khamûl

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #2 on: October 20, 2008, 12:04:55 PM »

The spin time of a bowling ball is the amount of time it takes a ball to migrate from a point equidistant from its 3 measured rg axes (as defined in the usbc equipment spec manual) to its highest rg axis while rotating on a free spin machine.
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CharlieBrown

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #3 on: October 20, 2008, 12:15:37 PM »
quote:
Hey mate,

I'm pretty sure its the time it takes for a ball to go from its unstable posistion to its stable posistion on a determinator. Lower rg cores will have a much quicker spin time and higher rg cores. I think its that anyway.


Hey Matt,

You can ask Mo when you see him in a couple of weeks.

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CharlieBrown

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #4 on: October 20, 2008, 12:21:52 PM »
MTD300, khamûl,

So, there’s no such thing as ‘bad’ or ‘good’ numbers then?!? Just ‘different horses for different courses’?

Is it possible to explain 'Spin time' and 'core stable/unstable positions' to me in layman’s term?

Thanks again.

On edit, I've just downloaded the 2008EquipSpecsManual.pdf from USBC, so I'll have a read....


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Edited on 10/20/2008 12:36 PM
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khamûl

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #5 on: October 20, 2008, 12:43:45 PM »

CB,

When you throw the ball, it transitions through 3 phases of motion skid, hook & roll. The balls spin time will represent how long the hook phase of the ball will last, higher spin times will translate to a longer hook phase.  The final spin time of the ball sill be determined by many factors designed into the balls core RG's, RG diff's, overall shape and location of densities.
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230-n-up-or-bust

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #6 on: October 20, 2008, 12:55:34 PM »
quote:

CB,

When you throw the ball, it transitions through 3 phases of motion skid, hook & roll. The balls spin time will represent how long the hook phase of the ball will last, higher spin times will translate to a longer hook phase.  The final spin time of the ball sill be determined by many factors designed into the balls core RG's, RG diff's, overall shape and location of densities.
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khamûl

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #7 on: October 20, 2008, 12:59:13 PM »


CB,

I do not know if the 08 manual has been updated based on the data that was presented in their ball motion study.  Some basic reading that may also be slightly outdated but more relevant might be here...

http://www.jayhawkbowling.com/DeTerminator/DeTmanual.pdf
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khamûl

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #8 on: October 20, 2008, 01:01:04 PM »
quote:
"What was that middle part?"


lol
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shelley

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #9 on: October 20, 2008, 01:21:08 PM »
quote:
Hey mate,

I'm pretty sure its the time it takes for a ball to go from its unstable posistion to its stable posistion on a determinator. Lower rg cores will have a much quicker spin time and higher rg cores. I think its that anyway.


Spin time is indeed the time required for the ball to migrate from an unstable axis of rotation to a stable one, but the highness or lowness of the RG isn't what controls spin time.  Rather, the intermediate differential is what influences spin time the most.

The high/low RG does affect how quickly a ball revs up.  Lower RG balls will rev up quicker than higher RG balls (khamul is talking about the transition from skid to hook to roll, and the time to rev up is something like the time to hook).  But that's not the same as spin time.

SH
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CharlieBrown

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #10 on: October 21, 2008, 06:05:40 AM »
Thanks khamûl and shelley, I'll do some reading when I have a chance. Hopefully it will all make sense to me!
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dizzyfugu

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #11 on: October 21, 2008, 06:21:16 AM »
Just as shelley put it - the spin time is a "practical" measure to show how fast a core migrates from an instable 60° initial position towards its stable end (roll) axis on a determinator device. Balls with a strong mass bias designed into the core, indicated by a high asym. RG differential will migrate quicker than weak MB balls (which can be both symmetrical or asymmetrical, that does not matter much). "Quick" cores are in the 5 sec. region - it tells you how fast the ball makes its move on the lane, which can be helpful if you want e. g. a ball that does a very sharp hook. If drilled appropriately, the core helps with/enhances the reaction shape.
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CharlieBrown

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Re: What does ‘Spin time’ mean in an asymmetric ball?
« Reply #12 on: October 21, 2008, 08:02:46 AM »
Cool dizzyfugu, thanks!
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