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Author Topic: locating the cg??  (Read 1907 times)

slashrr69

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locating the cg??
« on: June 19, 2009, 04:16:22 AM »
hello br members
  was wondering if someone could tell me how to correctly find the cg using a dodo scale.. or maybe someone knows of a site that shows how to do it.. I know lane1's site shows how to do a lane one ball, but I cant seem to get their procedure to work on my amf ball.. any info would be greatly appreciated.. thankss for your time.. slashrr69

 

J_w73

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Re: locating the cg??
« Reply #1 on: June 19, 2009, 04:06:45 PM »
I would think it would be the same procedure as the lane1 for any ball..

find where it balances 0 for each side of the ball... the center of those spots should be the center of gravity for the whole ball
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JohnP

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Re: locating the cg??
« Reply #2 on: June 19, 2009, 09:31:50 PM »
The Lane 1 procedure works for any manufacturer's balls.  They reference their logo when instructing how to rotate the ball after each balance.  If it helps, just draw a facsimile of their logo on your AMF ball and use it.  With the pin stacked above the marked cg, you want the initial line to be about a inch left of the marked cg and pin.  If that doesn't work, try moving the initial line further from the marked cg, in case it's mismarked really badly.  --  JohnP

slashrr69

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Re: locating the cg??
« Reply #3 on: June 19, 2009, 10:02:23 PM »
thanks for the help.. I took a couple other balls to try it out on and they worked according to the lane1 procedures(very little difference from its original cg were talking 1/8ths).. go figure!! the amf ball I was tring to find the cg on, must be wayway out according to where it ends up.. it is 1+13/16" difference of what it should be.. can this be correct on a 1st quality ball?? slashrr69

JohnP

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Re: locating the cg??
« Reply #4 on: June 20, 2009, 11:16:34 AM »
Yes, I've seen some 1st quality balls with cg's mismarked more than that.  You've got to remember that the QC dept can't manually check all cg's, so they accept whatever the in-line measurement is on symmetrically-cored balls.  For asymmetrical balls, I'm not sure it they recheck if the cg is out of line with the pin and MB or if they just sell it as a second.  If you want to confirm your location, mark the spot you've located and go back through the procedure again.  Or check the spot by setting the ball in the scale with the cg dead on top and balance the scale.  If you then rotate the ball, keeping the cg dead on top, the scale will balance at all positions if the cg is correct.  --  JohnP

slashrr69

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Re: locating the cg??
« Reply #5 on: June 20, 2009, 01:45:51 PM »
thanks again for the help "JP", spinning the ball like you said it does balance out every time you spin it.. it must be miss marked and is correctly marked now.. it IS a symmetrical ball and NOT a assymetrical so it really shouldn't make a big difference should it?? the big question is it is marked as a 3.5" pin but it is really a 5.25+"(you would think that would make it a 2nd and not a 1st quality ball).. does that make a big difference in how I need to lay the ball out now?? I have watched the brunswick video "the cg does not matter" and I understand what they are saying.. would like to hear some of your thoughts.. also, do you really think that the usbc is going to go away with the dodo scale(static weights) and what do you think about the 1" cg rule from your grip line no farther?? I think that one alone would make alot of bowlers mad because they would have to plug and redrill all their equipment..

JohnP

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Re: locating the cg??
« Reply #6 on: June 20, 2009, 09:18:22 PM »
It would have been a 2nd if they had realized where the cg actually was, they accepted what the in-line measurement said.  The only time it might make a significant difference in laying the ball out is if you did not want a balance hole.

My thoughts on the influence of static weights - they have the same influence they did in the days before dynamic cores, but the modern cores have so much more influence that the statics are now only important for USBC legality.  

As to what USBC will do, heaven only knows.  I don't think they will do away with static weight limits unless they impose a limit on cg location as a surrogate.  It would suit me fine if they required the manufacturers to have a circle around the cg so that as long as the grip centerline and midline passed through the circle the ball was legal.  That would eliminate a lot of weighing, but would put more pressure on manufacturers to get the cg and top weight accurate.  

Typically, when USBC makes that kind of change they "grandfather" in balls that have already been drilled and are legal under the old rules.  The only exception to this that I'm aware of is when Columbia introduced the Sur-D-Pro (could be spelled wrong, there were at least two versions) back in the soaker days.  --  JohnP