As far as I know you do not want to use a weighted ball, during your wind mill, while taking the ball over the shoulder. I was told that it is not good on your shoulder.
I have the weighted set of 4 balls, that I use very sparingly for flips and power Ks and for fun, to show kids the difference an ounce makes.
To give girls something with slightly more weight, I have driven finishing nails in the seams of the softball. Space them out, so the ball is balanced and hammer in about 6 of them. Weigh the ball on a postal scale and write the weight on the ball. It should be about 6.9, then, more nails will get you to 7.0, etc.
I am thinking of selling my weighted ball set, because I see no use for it.
Club K has a good program using weighted balls. The key is to not have too much additional weight to the ball. The heavy ball is 8.5oz and that is about 2oz heavier than normal and the set also comes with a lighter ball that is 5.5oz to improve arm speed. The key to reducing injury is correct mechanics and the additional weight should not create a problem as long as your daughter can handle the additional weight without changing motion.
I went to a clinic in January which one of the presenters was Pete Looney, the pitching coach of U Conn. He said it was alright to use weighted balls as long as you throw from about 20', start from the 9 o'clock position and don't force the throw.He said to never use a full windmill with a weighted ball.
I never go 100% with the weighted balls. I also don't do movement pitches with them at all. Its purely about the arm movement. (in fact when I bought them from my softball/baseball shop they quizzed me on them. They were very clear not to do too much with them as they can cause injury) I only have the one ounce heavier ball and I use that during practise and warming up before a game.
What's the reason behind using a weighted ball? It seems to me its a simillar concept to using a donut on your bat in the on deck circle which some (like Coach Marc D on this site) would say is wrong since it might change mechanics and fatigue the arm before a game?
Using weighted ball is supposed to be a type of resistance training. Let them throw heavy and then switch right back to light to get the arm moving faster. When I say heavy, I'm talking an oz. more regular Ball and then an oz. less then regular ball and only 10 to 12 reps. It sound good in theory but if it works is beyond me. I don't know if there is a risk of injury with this amount of added weight either. I have seen as much as 16oz. used at 50% of the arm speed on videos. It does not sound like a good idea to me.
Yeah that's a bad idea. I used to have the full set, but I've only ever used the 8 ounce ball (the lightest of the heavy balls) I lost that set when my softball kit was stolen out of my car (and I cried for like a week after that, I'd had that mitt for 15 years) and I only bothered replacing the green one.
I'm trying to get my hands on a light-weight ball but its hard over here.