No Thumb Ball Static Weight

Which layout is right for me?

Moderator: Moderators

Post Reply
rf67pccb
Member
Member
Posts: 200
Joined: October 20th, 2014, 12:13 am
Positive Axis Point: 4 7/8 over 7/8 up
Speed: 16.6 Camera
Rev Rate: 300
Axis Tilt: 12
Axis Rotation: 70
Preferred Company: Radical and Roto Grip

No Thumb Ball Static Weight

Post by rf67pccb »

If you have a no thumb bowler using/borrowing a ball to use in league that has 2 finger holes and a thumb hole that meets static weight for the conventional bowler what would the weights likely come out if checking the ball based on a no thumb bowler?

Would moving the check point from center of grip to middle of bridge cause a problem with either the finger or thumb/bottom weight? Anyone out there have experience with this?

Must the palm cover the thumb hole or does the new rule even relate to that?
Rorey Faiola
--------------
Right Handed
Speed 16.6 Off Hand
AT 12
AR 80
RR 300
PAP 4 7/8 Over 7/8 Up
User avatar
snick
BCU Graduate Layouts
BCU Graduate Layouts
Posts: 759
Joined: August 31st, 2014, 8:00 pm
THS Average: 196
Sport Average: 180
Positive Axis Point: 5.5625" x .625 up
Speed: 17 off hand
Rev Rate: 360
Axis Tilt: 17
Axis Rotation: 55
Heavy Oil Ball: Storm Physix
Medium Oil Ball: Storm Streetfight
Light Oil Ball: Rotogrip Hustle Pearl
Preferred Company: Rotogrip
Location: Tucson, AZ

Re: No Thumb Ball Static Weight

Post by snick »

Here's my take on it...
If the thumbhole can be used to grip the ball, I would expect the center of grip to be in the normal position on the mid-line.
If not, it's a balance hole, and the center of grip is between the finger holes.
Benchmark Bowling Pro Shop
Byron

RH
PAP: 5.5625 x .625 up
REVRATE: 360
SPEED: 17mph at release
AR: 55º
AT: 17º
rf67pccb
Member
Member
Posts: 200
Joined: October 20th, 2014, 12:13 am
Positive Axis Point: 4 7/8 over 7/8 up
Speed: 16.6 Camera
Rev Rate: 300
Axis Tilt: 12
Axis Rotation: 70
Preferred Company: Radical and Roto Grip

Re: No Thumb Ball Static Weight

Post by rf67pccb »

Apparently the latest specifications allow tape or slugs for a no thumb bowler in the unused drilled thumbhole why I don't know.

My question really is if a no thumb bowler uses a ball that was originally drilled for a bowler using his/her thumb with say a 3-4 inch pin would the options be limited when measuring static weight using the fingers as cog?

Would the no thumb bowler need to demonstrate that he/she could actually use that thumbhole? Or is static weight the only factor in determining legality? If the ball in question does not have the cg near center (kicked out) and the pin is also (kicked out) and you need to use the fingers as cog how can that ball be statically legal?
Rorey Faiola
--------------
Right Handed
Speed 16.6 Off Hand
AT 12
AR 80
RR 300
PAP 4 7/8 Over 7/8 Up
elgavachon
Trusted Source
Trusted Source
Posts: 3174
Joined: January 18th, 2010, 9:21 pm

Re: No Thumb Ball Static Weight

Post by elgavachon »

rf67pccb wrote:Apparently the latest specifications allow tape or slugs for a no thumb bowler in the unused drilled thumbhole why I don't know.

My question really is if a no thumb bowler uses a ball that was originally drilled for a bowler using his/her thumb with say a 3-4 inch pin would the options be limited when measuring static weight using the fingers as cog?

Would the no thumb bowler need to demonstrate that he/she could actually use that thumbhole? Or is static weight the only factor in determining legality? If the ball in question does not have the cg near center (kicked out) and the pin is also (kicked out) and you need to use the fingers as cog how can that ball be statically legal?
Low top wt balls can have a CG moved very far. You are allowed 1 oz. so if you only have 1oz to move around, you will be legal. High top wt balls have to have the CG close to the center of the grip or a balance hole.
rf67pccb
Member
Member
Posts: 200
Joined: October 20th, 2014, 12:13 am
Positive Axis Point: 4 7/8 over 7/8 up
Speed: 16.6 Camera
Rev Rate: 300
Axis Tilt: 12
Axis Rotation: 70
Preferred Company: Radical and Roto Grip

Re: No Thumb Ball Static Weight

Post by rf67pccb »

Here is my take....this no thumb bowler gets a ball from someone and likely does nothing to it. My experience is that "normal" players are not looking for a ball with short pins and low top weight.

I would think that average would be pins 3-4" and top weight near 3 oz. The ball he was throwing was from a player that would want aggressive layouts and has a really long span >5". So checking the ball using the fingers would in all likelihood be out on either top weight or finger weight.

Am I wrong in asking that the ball be verified? Is there a rule of thumb on inches equaling ounces. IE: 1 inch = 1 ounce. Anyone have an educated guess? This ball would move cog approximately 2 1/2 inches up for static weight check. I would think top and finger weight would be affected greatly.

This individual has been heard to say back when the rule change came about that he did not care and was not going to change any equipment! So he is aware of needed changes.
Rorey Faiola
--------------
Right Handed
Speed 16.6 Off Hand
AT 12
AR 80
RR 300
PAP 4 7/8 Over 7/8 Up
User avatar
Dustin
BCU Graduate Layouts
BCU Graduate Layouts
Posts: 892
Joined: June 5th, 2010, 11:55 am

Re: No Thumb Ball Static Weight

Post by Dustin »

Prior to the rule change I would drill a thumb hole in balls for 2 finger bowlers and after the rule change I have gone back and checked some of the same balls by using the bridge as center of grip and to my surprise they were still balanced. There are to many variables to say if the cg mark is x" away from the bridge and the thumb is y" deep by z" diameter it's balanced.
* MPH @ aarows
* RPM
AR *
AT *
PAP 3 3/4"
(* rebuilding)

“The good thing about science is that it's true whether or not you believe in it.”
― Neil deGrasse Tyson
User avatar
Dustin
BCU Graduate Layouts
BCU Graduate Layouts
Posts: 892
Joined: June 5th, 2010, 11:55 am

Re: No Thumb Ball Static Weight

Post by Dustin »

On second thought, if you new the top weight, the cg distance, and the diameter and depth of the thumb I guess you could estimate the balance, but nothing is more accurate than a scale (and a knowledgeable person to use it)!
* MPH @ aarows
* RPM
AR *
AT *
PAP 3 3/4"
(* rebuilding)

“The good thing about science is that it's true whether or not you believe in it.”
― Neil deGrasse Tyson
JohnP
Trusted Source
Trusted Source
Posts: 3432
Joined: January 31st, 2010, 1:04 am
Positive Axis Point: 15 15/16 x 3/16
Speed: 13.5 (Qubica)
Axis Tilt: 13
Axis Rotation: 45
Location: Hawesville KY/Tell City IN

Re: No Thumb Ball Static Weight

Post by JohnP »

When I drill a ball for a customer that wants to be able to use it both with and without using the thumb I first weigh the undrilled ball using both grip centers. From that information I can get a good estimate of where to place the cg to end up legal both ways. I usually end up placing the cg fairly close to the centerline (how close depends on the top weight) and about half way between the two grip centers. So far I haven't had to, but the finger/thumb weight can be adjusted by the depth of the holes. Also, so far no one has asked for a thumb slug or sleeve. -- JohnP
elgavachon
Trusted Source
Trusted Source
Posts: 3174
Joined: January 18th, 2010, 9:21 pm

Re: No Thumb Ball Static Weight

Post by elgavachon »

This is in the wiki. It has come out accurate for me.
http://wiki.bowlingchat.net/wiki/index. ... t_Calc.xls" onclick="window.open(this.href);return false;
User avatar
DarkHorse
Member
Member
Posts: 221
Joined: June 15th, 2013, 12:06 am
Location: USA

Re: No Thumb Ball Static Weight

Post by DarkHorse »

rf67pccb wrote:Here is my take....this no thumb bowler gets a ball from someone and likely does nothing to it. My experience is that "normal" players are not looking for a ball with short pins and low top weight.

I would think that average would be pins 3-4" and top weight near 3 oz. The ball he was throwing was from a player that would want aggressive layouts and has a really long span >5". So checking the ball using the fingers would in all likelihood be out on either top weight or finger weight.

Am I wrong in asking that the ball be verified? Is there a rule of thumb on inches equaling ounces. IE: 1 inch = 1 ounce. Anyone have an educated guess? This ball would move cog approximately 2 1/2 inches up for static weight check. I would think top and finger weight would be affected greatly.

This individual has been heard to say back when the rule change came about that he did not care and was not going to change any equipment! So he is aware of needed changes.
I've seen quite a few factory-marked CGs off by over 1", so the way the ball looks may not be how it weighs.

A drilled hole of a given size will remove the same amount of material wherever it is drilled on the ball (slight change due to core density, but pretty close), but in my experience, the further the hole from the grip center, the greater the change in static weights in that direction.

So, the original thumbhole used to be about 37 degrees from grip center, and as a balance hole is now 75 degrees from grip center. It may not be by much, but I believe that balance hole location has a larger effect on statics than as a thumbhole. If the starting CG was near midline, it is now 37 from the new grip center of the bridge, with a large (likely, given a 5" span) balance hole just a couple inches away in the same direction.

Also, consider that for the original bowler, the finger and thumb holes almost offset each other regarding static weights, since they are equal distance from the grip center.
For the no-thumb bowler, there is now 1 large balance hole in the thumb half of the ball, and no holes in the finger half of the ball.

Unless that ball started with 1/2 oz thumb weight or more, I can't imagine it being illegal.
Right Handed
Speed: 18 mph (foul line)
Rev Rate: ~350 rpm
Tilt: 10*
Rotation: 55*
PAP: 5 1/8" right, 1/2" up
JohnP
Trusted Source
Trusted Source
Posts: 3432
Joined: January 31st, 2010, 1:04 am
Positive Axis Point: 15 15/16 x 3/16
Speed: 13.5 (Qubica)
Axis Tilt: 13
Axis Rotation: 45
Location: Hawesville KY/Tell City IN

Re: No Thumb Ball Static Weight

Post by JohnP »

I've seen quite a few factory-marked CGs off by over 1", so the way the ball looks may not be how it weighs.
True, but in the last 4 - 5 years I've seen fewer than before. If I have any doubts about the layout I weigh the ball before drilling it based on the layout to be used. That gives me the information needed to decide if layout changes are needed.

A drilled hole of a given size will remove the same amount of material wherever it is drilled on the ball (slight change due to core density, but pretty close), but in my experience, the further the hole from the grip center, the greater the change in static weights in that direction.
Any hole drilled removes weight divided between the +/- side, finger/thumb, and top/bottom sectors. For example, a balance hole drilled on grip center removes all top weight; drilled on the + side intersection of the centerline and the midline it removes all + side weight, if drilled between the two points it removes weight from the + side and top weight sectors; etc. When you leave the sector boundaries it removes weight from all three sectors proportional to its distance from each sector boundary line. I'm sure there are formulas to calculate the distribution, but with a little experience I've been able to estimate satisfactorily. -- JohnP
Post Reply