Author Topic: Weight removal (Read 14123 times)

qstick777 · « **on:** March 24, 2010, 04:14:41 AM »

Without getting into a discussion on the importance (or lack thereof) of ending weights, I'm trying to get a better understanding of laying out balls to achieve a desired ending weight - either because of a customer request or for planning on a particular weight hole location.

Given the USBC guidelines:

quote:
Balance:
The following tolerances shall be permissible in the balance of a bowling ball used in certified competition:
1. 10.01 pounds or more:

a. Not more than 3 ounces difference between top half of the ball (finger hole side) and the bottom half (side opposite the finger holes).

b. Not more than 1 ounce difference between the sides to the right and left of the finger holes or between the sides in front and back of the finger holes.

c. A ball drilled without a thumb may not have more than 3 ounces difference between the top half and bottom half of the ball.

d. A ball drilled without any finger holes or indentations, may not have more than 1 ounce difference between any two halves of the ball.

e. A ball used without any hole or indentations may not have more than 1 ounce difference between any two halves of the ball.

Say a customer comes in and is dead set that they want a ball drilled with 1 oz finger weight, 3/4 oz of positive side weight, and absolutely no bottom weight.

Using the weight removal chart as a reference: http://www.bowlingball.com/weight-hole-remove-chart.html

Turbo quad inserts - 31/32" x 1.75" hole = 1.050 oz per finger hole., so 2.1 oz is removed for both fingers. I'm not sure how much the inserts weigh, so I don't know how much to add back in for those. If anybody has that info it would be great, if not I'll have to see if I can get that info tonight.

1 1/4" thumb slug - 1.25" x 3" hole = ~2.70 oz. Again, not sure how much a drilled slug weighs to add that back in.

Okay, so given that info, how would you go about laying out the ball. What type of specs would you look for as far the top weight is concerned? It seems that drilling the finger and thumb holes take out almost 5 oz. Is it even possible to drill a "1st quality" ball and end up with top weight?

T C 300 · « **Reply #1 on:** March 24, 2010, 12:58:19 PM »

couldnt you just lie to them???

LOL

qstick777 · « **Reply #2 on:** March 24, 2010, 01:12:28 PM »

quote:
couldnt you just lie to them???
LOL

I guess that''s always an option!

Still, just trying to get a little more education.

Brunsnick was nice enough to answer most of the question on askthebowler.com - http://askthebowler.com/bill_taylor_shifter.html.

I guess the top and bottom weight are the only things I don''t really get.

From here it says:

quote:
Top/Bottom Weight

As mentioned previously, bowling balls come with extra weight placed under the center of gravity punch on the ball to balance out the weight taken out by drilling holes. This weight is called top weight because it is located in the top of the bowling ball. Bowling balls generally are manufactured with anywhere from two to four ounces of top weight although it is possible to find balls that fall outside that range. Lightweight balls are made with less top weight generally for two reasons. Light balls generally are drilled for children so the holes are smaller, meaning there is less weight removed that needs to be balanced out. Also, since the ball has less total weight, an ounce or two of top weight will have more effect on the ball''s dynamics and throw them "out of whack."

Top weight has a similar effect as finger weight: the ball will go longer down the lane and snap a bit more on the backend. Likewise, bottom weight is like thumb weight in that it makes the ball roll earlier and arc more.

Unlike other static weights, ABC/WIBC regulations allow up to 3 ounces of either top or bottom weight. This is measured on the dodo scale by comparing the drilled side of the ball (top) to the non-drilled (bottom) side of the ball.

Top and bottom weight are not necessarily caused by shifting the CG away from the center of your grip. They are more a result of how much extra weight the manufacturer placed in one side of the ball and how much weight is removed from that side during drilling. However, you can alter top weight and bottom weight by shifting the CG. Because top/bottom weight are measured by comparing the grip side of the ball (the top) to the non-grip side (the bottom), if you shift the CG away from the center of the grip, you are moving it around the circumference of the ball towards the bottom. You would be removing top weight (and/or adding bottom weight depending on how you look at it) by shifting the CG. Therefore, the most top weight you can have in any particular ball after drilling (and before drilling any extra holes) would be if the CG is directly in the center of the grip.

Just wondering if most balls have between 2-4 oz of top weight, and you are taking out almost 5 oz with the drilling (not including the amount added back by the inserts and slug), is it really that likely to end up with top weight on a ball?

Obviously not so much of an issue if you don''t use inserts or slugs, and possibly even more of an issue if you use an IT or switchgrip setup (with the 1 1/2" thumb hole taking out even more weight).

Edited on 3/24/2010 1:12 PM

charlest · « **Reply #3 on:** March 24, 2010, 02:53:42 PM »

quote:
I'm trying to get a better understanding of laying out balls to achieve a desired ending weight - either because of a customer request or for planning on a particular weight hole location.
Using the weight removal chart as a reference: http://www.bowlingball.com/weight-hole-remove-chart.html

Turbo quad inserts - 31/32" x 1.75" hole = 1.050 oz per finger hole., so 2.1 oz is removed for both fingers. I'm not sure how much the inserts weigh, so I don't know how much to add back in for those. If anybody has that info it would be great, if not I'll have to see if I can get that info tonight.

1 1/4" thumb slug - 1.25" x 3" hole = ~2.70 oz. Again, not sure how much a drilled slug weighs to add that back in.

qstick,

Just to give you one situation and I'm not saying you should or should not rely on this. I'm not a driller, but I've been using the same set-up for 15 - 20+ years now. Contour power grips for the fingers (31/32" diameter. 1 1/2" deep, and an oval thumb inserts, 1 1/8" in diameter, 2 3/4" deep, usually but not always from Contour). I also just checked the depth of my finger holes. They're 1 7/8" deep (I was surprised).

I asked my driller to weigh the ball a couple of times before and after drilling. On average, those 3 holes average between 2 and 2.25 ounces of removed weight together. So I was very surprised when the bowlingball.com chart gave 2.1 oz as the weight removed FOR JUST THE FINGER HOLES.

--------------------
"None are so blind as those who will not see."

BKloss · « **Reply #4 on:** March 24, 2010, 03:08:04 PM »

Is this even possible to do between finger and thumb?
Reason I ask is what happen if you drill your thumb 2.75" deep and hit the core, the core is more dense than any filler right?

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kidlost2000 · « **Reply #5 on:** March 24, 2010, 03:09:35 PM »

For 1 oz finger weight and 3/4 oz side weight The cg will need to be on the positive side of the ball and closer to the fingers at least the top half of the bowlers span of the ball.

Depending on the top weight of the ball will depend on how much in either direction. You can pre draw your lines and then weight the ball like it has been drilled to give you an idea on side weight and what fingers and thumb weight would be before drilling them. You can then guesstimate using the numbers you have above for what the actual weight would be after drilling fingers and thumb.

Pin placement should come first when laying out a ball.
--------------------
" men lie, women lie, numbers don't "

JohnP · « **Reply #6 on:** March 24, 2010, 09:30:17 PM »

I would get a ball with 4 oz of top weight and check the cg location and top weight on my dodo scale. Let's say they are both correct. I would put the cg 1 1/2" above the midline and 1 1/4" right of the centerline (for a right hander). Drill the holes to standard depth, glue in the slug if used, and drill the thumb hole. Remove the ball from the jig and place (don't glue) the finger grips in their holes. Weigh the ball, it should have around 1 1/4 oz of finger weight, 1 oz of side weight, and 1 oz of top weight. Put the ball back in the jig and drill the fingers deeper, removing several times and reweighing for finger weight. When I got to about 1 1/8 oz of finger weight I would drill a balance hole on the midline 6 3/4" from grip center, reweighing for side weight until I got exactly 3/4 oz. Reweigh completely, there should still be a little finger weight over the 1 oz. Drill each finger an equal amount deeper. reweighing until the finger weight is exactly 1 oz. Side weight will still be 3/4 oz and there should still be a little top weight (he just said no bottom weight so top weight is OK). Note that I haven't worried about pin placement or whether the flare rings will hit the balance hole. This dunce of a customer didn't ask for performance, just a specific list of meaningless static weights. It did make for an interesting mental exercise, though. -- JohnP

qstick777 · « **Reply #7 on:** March 25, 2010, 12:34:02 PM »

Wow guys thanks for the responses. I guess I should have been more clear that this isn't an actual situation, just more for my ability to better conceptualize these things before laying out a ball. I only drill for myself, so I'm not overly concerned with ending weights - as long as they are legal.

But I did come across some balls that I had forgotten about - some with less than ideal specs - and it got me thinking about whether I wanted to drill them or sell them, and how I would go about laying them out.

Plus, I remember hearing some guys talking about how a ball wasn't hooking like they thought and it must be because it had too much bottom weight. You tend to hear finger and side weight, but not much about bottom weight.

Got to looking and most of my balls have around 3 oz of top, so trying to figure out if it's even possible to drill these holes and still have any top weight left.

charlest:
I've heard that those charts aren't really accurate anymore, just using them as a guideline. In the past I've had to drill much deeper than the chart recommended to remove the proper amount of weight, so it would seem the charts are a little on the high side.

Bkloss:
Not sure if it's possible. Just wondering. Using those numbers, it doesn't seem possible, that's why I asked.

kidlost2000:
I know I can do that - but very rarely do I!

Pin placement is always the first concern.

JohnP:
ummm, wow. Not sure what to say. That was far more detailed than I imagined. But I do appreciate it! I'll have to see if I had something laying around with 4oz of top and actually lay it out like that! Something tells me you'll be right on the money!

JohnP · « **Reply #8 on:** March 25, 2010, 08:44:12 PM »

quote:
Plus, I remember hearing some guys talking about how a ball wasn't hooking like they thought and it must be because it had too much bottom weight. You tend to hear finger and side weight, but not much about bottom weight.

Got to looking and most of my balls have around 3 oz of top, so trying to figure out if it's even possible to drill these holes and still have any top weight left.

As long as you're dealing with a ball with a dynamic core and reactive coverstock, forget about static weights as long as they are legal. They do have a very minor affect on reaction, but it is insignificant compared to other parameters.

The amount of weight taken out depends on the diameter and depth of the holes. For someone with small fingers and not using grips it's very possible to end up with top weight. -- JohnP

qstick777 · « **Reply #9 on:** March 26, 2010, 06:52:52 AM »

quote:
quote:
Plus, I remember hearing some guys talking about how a ball wasn't hooking like they thought and it must be because it had too much bottom weight. You tend to hear finger and side weight, but not much about bottom weight.

Got to looking and most of my balls have around 3 oz of top, so trying to figure out if it's even possible to drill these holes and still have any top weight left.

As long as you're dealing with a ball with a dynamic core and reactive coverstock, forget about static weights as long as they are legal. They do have a very minor affect on reaction, but it is insignificant compared to other parameters.

The amount of weight taken out depends on the diameter and depth of the holes. For someone with small fingers and not using grips it's very possible to end up with top weight. -- JohnP

Yeah, I don't put too much into the ending weights, other than to make sure they are legal.

It just got me thinking that I believe it's been a long time since I checked a drilled ball and it actually had any top weight.....especially since I started using the quad grips. In some of the used balls I've purchased, I've actually resorted to cutting the grips to make them fit instead of drilling the fingers deeper.

When I first got my scale I weighed up everything, but I seldom even check top and bottom anymore. I think you'd need to have less than 2 oz of top before even having to worry about checking top and bottom.

JohnP · « **Reply #10 on:** March 26, 2010, 04:38:19 PM »

Yes, I cut off the bottom of all the Quads that I install. And you're right, most balls I drill end up with bottom weight. I think some ball manufacturers target lower top weight now than they used to so there's less trouble meeting side and/or finger/thumb weight limits. -- JohnP

Author Topic: Weight removal (Read 14123 times)

qstick777

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T C 300

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