question about finger hole drill depth??? help needed

[stigmata]

hey everyone, got a question i noticed a little bit of powdery chips coming out of the fingertip holes on my newly drilled visionary immortal pearl, so i decided to pull out the fingertips and wow since i never have drilled a ball myself i dont know exactly how "deep" is too deep... i used to be a machinst so i used my digital calipers to get the depths...
ring finger hole is 3.41" deep
middle finger hole is 2.77" deep

and the insert itself is a vise fingertip and its only 1.61" long.....

i just want to know if any of the pro-shop owners can chine in and let me know if its too deep, and may effect the core dynamics......

[stigmata]

i also forgot to put this ball was drilled at a local pro shop

[bowl1820]

Not a pro shop owner but...

For a comparison the holes on my balls are about 1 3/4" deep.

So that sounds a little deep to me for a fingertip ball, but if the ball had too much top weight (it would have to be a lot). He may have went deep to lower it.

Also I believe it lowers the flare potential a little bit, depending on the pin location. Drilling the fingers deeper make the core shorter, and lowers the differential.

The geometry factors of finger and thumb weight mean the balls CG is either shifted up or down towards the finger or thumb holes. Basically, finger weight will make the ball go longer down the lane and have a snappier backend reaction. Thumb weight makes the ball roll sooner and have more of a smoother arc when it starts to hook.

But if the ball works ok for you don't worry about. Now they could fill the holes back up a little with plug material, it would put a minor amount of weight back in.

[stigmata]

the top weight of the ball was 2.71 and for pin location if i measure from the center of the pin to the center between my fingertip holes(bridge?) its 1" ..and the thumb hole is 4.25" left of the "virtual mass bias" according to the visionary drill sheet.....and the ball don't react how i want it too actually it has practically no arc at all....and that is with me dulling the shine to #000 synthetic steel wool(im guessing 1500-2000 dull) the only way it curves is if i were to bowl 2 fingered and put a million revs on it....

one of the owners helpers drilled (18yr old kid) granted age really dont matter but i think he may have made a mistake and just not said anything.... i didnt even notice actually how deep the holes were till i looked in with the flashlight

[JaxBowlingGuy]

could just be due to the fact of making the ball legal... you can only have 1oz of finger, thumb, and side weight... some shops i hear dont really even push the limit of the 1 oz and just cut the weight down to next to nothing... could be your issue here.. without weighing the ball it would be hard to know... it does sound a little too deep though even if takin weight out..

[playbowl]

hey everyone, got a question i noticed a little bit of powdery chips coming out of the fingertip holes on my newly drilled visionary immortal pearl, so i decided to pull out the fingertips and wow since i never have drilled a ball myself i dont know exactly how "deep" is too deep... i used to be a machinst so i used my digital calipers to get the depths...
ring finger hole is 3.41" deep
middle finger hole is 2.77" deep

and the insert itself is a vise fingertip and its only 1.61" long.....

i just want to know if any of the pro-shop owners can chine in and let me know if its too deep, and may effect the core dynamics......

Finger holes are just one of the ways to remove weight to bring a ball into USBC specs.
The Visionary Immortal is a lower Rg ball already. By removing material in the fingers up to 1.75" the driller is LOWERING the Rg of the ball. Once past that, the Rg begins to go back to the original spec.
If there is no balance hole then this ball was probably a 2-3" Pin ball and they were trying to remove finger weight as stated above. That ball has a very high differential from the factory and will flare a lot. I almost purchased one in Las Vegas because they were manufactured with a higher differential than allowed by current USBC standards and the balls were grandfathered in as legal.

Watch to see if the ball isn't rolling out on you by reading the lane too early. Play deep on a THS.

[stigmata]

thanks for all the help !!!! ....

PLAYBOWL- it dont matter where i stand or release the ball just wont do anything ..... and i brought it to a pro shop that my best friend refered me too and his whole family and i guess most of the people on his league swear by the guy cause he knows his stuff.... and i gave him the ball and was told it was laid out wrong so its getting redrilled as i write this :D

[JaxBowlingGuy]

layout wrong for how you throw or wrong as in not legal? if they drilled a illegal ball id be trying to get some $ back. lol

[stigmata]

oh lol, its laid out wrong for how i bowl..... it was drilled pinB/MB1 ...being moved to pinC/mb4 w/pin below ring finger:D

[playbowl]

oh lol, its laid out wrong for how i bowl..... it was drilled pinB/MB1 ...being moved to pinC/mb4 w/pin below ring finger:D

Stigmata

In theory, with the pin below your ring finger the ball should roll up quicker and depending on how you roll the ball (find the Positive Axis Point - PAP) the relation to the CG and VMB determines the ball reaction. The angle created in relation to how you deliver the ball is EXTREMELY important. The positions you cite above are relative to bowler style and if the pro shop did everything necessary to recommend a drilling pattern for you to get a certain reaction then you as a bowler need to figure out what it takes for the condition you bowl on. It may just not be a good match. Try it on oiler or dryer conditions than usual. Try it on shorter or longer patterns than usual. There is a lot of research that went into that ball to do certain things, don't expect it to do something it can't. From what I see in the specs of the ball it is a high flare, quick revving ball that wants decent oil. Throw it fast in oil and polish it up. The 1500 Abralon finish from the factory will have that ball hooking at your feet. Hope that helps.

[JAnderson]

Also I believe it lowers the flare potential a little bit, depending on the pin location. Drilling the fingers deeper make the core shorter, and lowers the differential.

It depends on whether or not any core material is removed when the finger and thumb holes are drilled and the resulting core shape/mass distribution. The same is true for pins above or below fingers. Generally speaking, I agree that pins below the fingers tend to help create earlier hook, but if no core material is removed either way, pin below or pin above will have the same effect. Pancake "cores" are a good example, but not the only example.


The angle created in relation to how you deliver the ball is EXTREMELY important

There are different schools of thought on this. The USBC and Brunswick maintain that surface preparation and pin placement are the two biggest non-bowling/non-lane-condition factors on ball movement and that changes in layout cause a much smaller change in ball movement. My experiments back up the surface argument. You can take a ball with a layout that is "strong and early", polish it up with turtle wax (clogs the pores) and (all other factors equal) make it go stick straight. Take a ball with a "length" or weak layout and sand it down to 80 grit and (all other factors being equal) it is going to hook at your shoe laces. I have yet to see a change in ball layout - however drastic - create such large changes in ball movement.

[playbowl]

JAnderson you wrote:

The USBC and Brunswick maintain that surface preparation and pin placement are the two biggest non-bowling/non-lane-condition factors on ball movement and that changes in layout cause a much smaller change in ball movement.

Absolutely - See the USBC Ball Motion study for the effect each has on overall motion. Great information.
Stremmel/Ridenour

[JAnderson]

The bowl.com site seems to be unreachable for me today, so I can't verify the link to the study, but I believe it is http://www.bowl.com/articleView.aspx?i=14185

There's an introduction and overview that was written before the study:
http://www.bowlingdigital.com/bowl/node/3473