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Author Topic: Pin up vs. pin down, misinformation?  (Read 29588 times)

tgknukem

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Pin up vs. pin down, misinformation?
« on: February 20, 2014, 04:15:26 AM »
In the 'Basic Top Weight Question' thread, it appears it was generally agreed upon that static weights have minimal to no effect on ball performance.  If this is the case then how does drilling a ball 'pin up' vs. 'pin down' affect ball motion?  Having the pin above the fingers or below does not affect radius of gyration, the only affects would be on the location of the bowties and static weights(i.e. finger or thumb weight).  The ending static weights would also be dependent upon pin to CG distance and weight removal during drilling.  I'm not aware of any way that drilling a ball 'pin down' can make it 'early revving' unless the final statics are  thumbweighted, or if the pin is less than 3 3/8 inches from the PAP and 'pin down'.
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itsallaboutme

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Re: Pin up vs. pin down, misinformation?
« Reply #31 on: February 22, 2014, 09:45:20 AM »
Soooo, is a bowler's rev rate going to be calculated using a ball drilled on the high or low RG axis or are we going to diddle in the middle?  And where do we find the person that is consistent enough for the couple of percent variance to make a difference?

Glad I didn't read about stuff like this when I still bowled.  Would have been even harder to let it go than it already was.
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todvan

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Re: Pin up vs. pin down, misinformation?
« Reply #32 on: February 22, 2014, 10:16:38 AM »
Pin up (lower VAL angle) use up the hook energy in a shorter, more sudden manner.
Pin down (higher VAL angle) spread this energy out over a longer area, more gradual.

This is due to the difference in initial rotation compared to where the ball wants to spin.

I'm getting the argument that a higher Rg layout (outside edge weight - think flywheel) is theoretically harder to get started spinning than a lower Rg layout (center heavy) - so maybe the bowler could put more revs on the lower Rg ball - but I'm just not sure that the difference in Rg is enough to give a measureable difference.
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tgknukem

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Re: Pin up vs. pin down, misinformation?
« Reply #33 on: February 23, 2014, 02:18:35 AM »
I had now come to understand that the physics guys are wrong when they claim that the two physical properties of an object, it's mass, and the distance of it's moment of inertia from it's axis(radius of gyration), are variables in determining the rate at which I can spin it.  The only variable in determining this is my bowler's attributes.  I was  both excited and apprehensive at what I was now going to do.  My auto insurance adjuster was probably going to get pretty upset.  I went out to my car and applied my bowlers attributes to it knowing that it's mass had nothing to do with me being able to spin it at 300 RPM, just like my Angle Evolution.  I tried...zero RPMs.  Tried harder...still zero RPMs.  I stood there stunned and in disbelief.  What to do now...I thought "put the pin below the fingers?"  Then it hit me, the physics guys were right all along...mass of an object IS a variable for the rate at which I can spin it.  A Mazda M3 hatchback is an object with physical properties just like an AMF Angle Evolution.  So if the physics guys are right about the mass variable, I'm guessing they are right about the radius of gyration variable
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itsallaboutme

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Re: Pin up vs. pin down, misinformation?
« Reply #34 on: February 23, 2014, 06:34:25 AM »
What's the RG of a Mazda?
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JustRico

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Re: Pin up vs. pin down, misinformation?
« Reply #35 on: February 23, 2014, 07:16:50 AM »
Dude I'm not exactly sure what you're trying to argue other than you have an understanding of physics...
So if you don't push the accelerator does the car go anywhere Mr Science guy? You're arguing semantics...

What's the potential of a bowling ball? If a car has a set rpm, it will go that fast no matter who is driving-no!
How much do you honestly believe a bowling ball will spin more in a 60' playing field? And if you have 150 rev rate vs a 400 rev rate the bowling ball will spin more relative to the applied forces but you still have 250 MORE rev rate...it's relative I'm not sure you get that
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tgknukem

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Re: Pin up vs. pin down, misinformation?
« Reply #36 on: February 23, 2014, 07:39:07 AM »
I called Mazda.  They said the minimum RG of a Mazda 3 hatchback is 2.51 and the maximum is 2.55, so it is withing USBC specifications.  I didn't see it on the approved list for the PBA tour though.
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Impending Doom

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Re: Pin up vs. pin down, misinformation?
« Reply #37 on: February 23, 2014, 07:41:51 AM »
I went to Lowes last night and bought the biggest hammer they had. Suddenly, I became Thor. It was awesome! Best life altering tool ever!

 
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itsallaboutme

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Re: Pin up vs. pin down, misinformation?
« Reply #38 on: February 23, 2014, 07:48:24 AM »
I know a guy who blew an engine in a Mazda 323 while bowling on the PBA Tour.  Does that count?
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