Author Topic: Mass Bias differential? (Read 10352 times)

Next Level PS · « **on:** September 07, 2005, 05:03:27 PM »

How can the Mass Bias differential be the same in two balls (rotogrip Epic and Total Shock and Awe) but have two different Spin times, one being nearly twice as fast than the other?
could it be something the core height or the rg?

....Just tring to get my masters in this then hopefully my PHD.
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Next Level PS · « **Reply #1 on:** September 08, 2005, 11:13:43 AM »

quote:
Spin time is a combination of factors .. the balls primary influence in terms of flare is the main pin which want to move towards your track. Once the main pin starts having less influence than the Mass Bias, the Mass Bias then tries to work it way towards the balls preferential spin axis. When the pin is on the track and MB is on teh PSA the ball will rest.
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ROTO GRIP & STORM
at
www.rpsbowling.com - Get a Grip

HMMMM....

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rotomike · « **Reply #2 on:** September 08, 2005, 11:25:21 AM »

The shortest answer is the difference between size and shape of the two cores in question.
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Mike Sinek
Roto Grip Advisory Staff
Kingdom member for life

mrh57 · « **Reply #3 on:** September 08, 2005, 12:45:20 PM »

The spin time tells you the strength of the mias bias. Height and size of the core will effect the lane reaction but according to morich website the determinator spin time only measure the strength of the mias bias.

BTW someone did a spin time on a Moric determinator for the Epic and posted the information to this messageboard. I think the average time was around 5 seconds.

Edited on 9/8/2005 12:37 PM

Next Level PS · « **Reply #4 on:** September 10, 2005, 01:33:56 AM »

Thanks Precision, for helping me out on this one!!

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www.nextlevelproshop.com

Iketown300 · « **Reply #5 on:** September 10, 2005, 02:24:29 AM »

quote:
The shortest answer is the difference between size and shape of the two cores in question.

But if this is the case doesn't that go against what brunswick has said all along, that the shape and size of the core make no difference only the numbers i.e. rg and diff?
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Ike Brownfield
PBA 05-06

charlest · « **Reply #6 on:** September 10, 2005, 04:32:17 AM »

One thing people seem to continue to forget in these discussions, which Pinel mentioned in his BTM articles was the coverstock. To keep things at the same starting point, he sanded all the balls to 2000 grit BEFORE putting them on the machine.

HOWEVER!!!!
this still does not take into account the different friction ratings of the different coverstocks even when kept at the same grit. After all, the gripping mechanism on the rollers of the machine are grabbing the ball's surface.

When we talk about flare (duller balls will flare more and earlier than polished balls) and length and all other factors, the surface must also be taken into account. Why don't we also have to do that for this machine?

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Bowling: Just like hand grenades and horse shoes, you only have to get close.
Life: Deal with what is.

charlest · « **Reply #7 on:** September 10, 2005, 06:22:03 PM »

quote:
The rollers on the Determinator offer much more traction than a lane surface with conditioner applied. The rollers are designed to get the ball rotating but still allow the ball to find its PSA efficiently regardless of the coverstock type or surface prep due to the roller hardness and footprint between coverstock and roller. This is why we're getting a true representation of the core dynamics.

When Mo, in his article, stated that the covers should start at the same grit level/degree, I assumed that the rollers would also reflect a different coefficient of friction for different coverstocks. SOme of them are VERY different, while some are very close.

Are the rollers' surafce so rough that they remove all differences in the coverstocks' coefficient of friction?

quote:

I believe I understand what your intent is with your statement comparing dull and polished balls in regards to the difference in flare. However, as you know I like to be technically correct so I'm going to edit it just a bit (not all dull balls flare earlier and more than polished ones, there are just too many factors involved such as core, cover, rev rate, axis rotation, lane and lane conditions).

If we examine the flare of two identically drilled balls released with identical technique on identical lanes and lane conditions with the only difference being one is polished and one is dull we will see a difference in flare. That difference will be that the polished ball will maintain axis rotation angle and tilt longer. Also, because the ball is not encountering as much friction as early as its dull counterpart, the polished ball will maintain its initial axis of rotation longer (axis migration will start sooner on the dull ball). Because the dull balls axis migration begins sooner due to the friction it encounters we will see earlier flare separation on the balls surface. Also remember that balls can flare both in the conditioned parts of the lane and the unconditioned areas (backend).
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Precision

My only point was that for the same ball, when it is finished dull(er), it will flare earlier and, very possibly more, than the same ball when it is polished. I was only trying to point out this factor, rather than comaring balls of different coefficients of frictions. Their flaring can be very different; polished or pearlized balls will flare more, in general, at the backend, which is part of their energy saving benefits.

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Bowling: Just like hand grenades and horse shoes, you only have to get close.
Life: Deal with what is.

Edited on 9/10/2005 6:13 PM

charlest · « **Reply #8 on:** September 11, 2005, 08:08:52 AM »

quote:
There are three coefficients of friction which come into play. Static coefficient of friction (friction by static weight), molecular coefficient of friction (friction by adhesion of two materials, ball surface and roller surface)and deformation coefficient of friction (footprint between two surfaces, ball surface and roller surface). For any given weight ball the static coefficient will be the same (say 2 15# balls). What could change with different surfaces is the molecular coefficient of friction and/or deformation coefficient of friction. All three will have an effect but will not be enough to drastically alter the spin times that are produced. Maybe we'll see differences in the 0.01 second range but keep in mind we are timing with a hand-held stopwatch and the margin for error of that alone is outside of that range. I know that earlier versions of the Determinator did have rollers with a different profile and they might have also had a different hardness (I'll confirm the hardness question next time I speak with Mo). We've ran tests with varying the ball surface on several test balls from 180 grit dull to 4000 grit polish and noticed no difference in spin time results.
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Precision

Thanks for the details. I won't have to bring this up again. I had thought it was important, based on Mo's original articles in BTM.

Oddly, I would have thought that the Determinator would have had a built-in timer. Indeed, that the timing is done by humans makes all those 10ths and 100ths of a seconds in some of the measurements seem ludicrous, unless it was an average of 50 - 100 trials for each ball, which I kind of doubt it was. The human factor does make the difference in ball's "friction"s unimportant.
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Bowling: Just like hand grenades and horse shoes, you only have to get close.
Life: Deal with what is.

blockhater · « **Reply #9 on:** October 07, 2005, 07:50:58 PM »

Precision, thank you for your insights. You truely live up to your name!

I love technical facts as much as the next physics student (or ex in my case) but can I just ask a few questions on this with a specific goal..

What affect does the Spin time have to ball motion on the lane?

How does mass bias differential affect ball motion for 2 balls drilled identically?

How much change in ball reaction is observed from moving the mass bias on a strong MB diff ball vs a weaker one. (0.25 vs 0.10)

Reason being, I am going to drill a Paradigm this week and am wondering how. This is going to be the strongest MB diff ball I have had to date..

Many thanks for your help on this.

Re-Evolution · « **Reply #10 on:** October 08, 2005, 03:10:40 AM »

Precision,

That is one of the best explanations I have ever read.
My thoughts are that if you have 2 balls that are statically and dynamically identical and have the same cover composition but different surface grits there could be a VERY small difference in spin times.

I looked at it in a different way than most would though and would like your input since you are obviously an analytical person.

For comparisons sake lets say we have a 320 grit ball and 2000 grit ball.

I think of it like a treaded tire versus a slick tire, since we are dealing with 2 balls that would have virtually identical amounts of deformation and the rollers have none.
Would the 2000 grit ball actually have a higher coefficient of friction due to it having slightly more contact surface like a slick tire does on dry pavement.

To elaborate on this further I feel that a polished ball not only has more backend because it has more energy but also because it has more contact surface when there is no liquid medium that has to be cut through for traction.

Do you agree?

I realize that seeing the differences would require sophisticated measuring equipment but I feel there would be a difference if a person had access to the equipment.

I also realize that this would give a diminishing return and you would start to move backwards at some point, where those points are I haven't a clue.

Too bad the determinator doesn't give you a revolutions to PSA instead of time, then I wouldn't have these thoughts
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STORM TRACK

www.Bowling-Info.com

BR.com's unofficial FAQ section

Edited on 10/8/2005 3:13 AM

Re-Evolution · « **Reply #11 on:** October 08, 2005, 12:58:52 PM »

quote:
Also keep in mind that the two balls have to be the exact same roundness and have the exact same molecular composition, if one ball is a little more out of round when compared to the other or the molecular coefficient is different it will show up in the spin times recorded.

I have also considered that the diameter of the ball will affect the actual on lane reaction and spin time. My thought is that if you have 2 balls that are identical other than 1 is at the minimum and 1 the maximum for allowable diameter. I think that the one with the smaller diameter will have a faster spin time and on lane transition, since it will have a slightly lower RG and would have more RPM when spun at the same velocity.
Again the differences would be minimal but when enough small factors come together they can become rather influential.
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STORM TRACK

www.Bowling-Info.com

BR.com's unofficial FAQ section

blockhater · « **Reply #12 on:** October 09, 2005, 09:00:49 AM »

Thanks Precision.

I really get on with balls when I have the mass bias closer to the thumb (for the kind of skid/snap reaction I'm looking for out of this one). As I said though generally I'm talking about stuff with weaker MB numbers, if this makes a significant difference.

For balls that do NOT retain PSA after drilling, does this mean we can affectively ignore the mass bias marking as a refernce point? My shop has a de-terminator, I'd love to experiment and try to gain some info from it.

Author Topic: Mass Bias differential? (Read 10352 times)

Next Level PS

Mass Bias differential?

Next Level PS

Re: Mass Bias differential?

rotomike

Re: Mass Bias differential?

mrh57

Re: Mass Bias differential?

Next Level PS

Re: Mass Bias differential?

Iketown300

Re: Mass Bias differential?

charlest

Re: Mass Bias differential?

charlest

Re: Mass Bias differential?

charlest

Re: Mass Bias differential?

blockhater

Re: Mass Bias differential?

Re-Evolution

Re: Mass Bias differential?

Re-Evolution

Re: Mass Bias differential?

blockhater

Re: Mass Bias differential?