Principles behind a ball pitching machine

  • Thread starter dilby
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Hi all -

I'm not an engineer or even very good at physics, but I was hoping to learn about something I'm interested in. I bought a ball pitching machine that i've outgrown and I'm wondering about either modifying it or even building my own and wanted to know about some of the key principles behind it's physics.

In short, a ball rolls down a tube that is slightly intersected with a large spinning wheel, which has a speed control. The ball brushes this wheel and is projected out. The wheel itself is quite large (30cm), and makes for a relatively immobile machine. I was wondering whether I could reduce the size of this wheel and was wondering how this would affect the performance. (Also other factors i imagine might be the wheel's speed and even perhaps width). So are there principles out there that anyone knows of that I can be pointed in the direction of?

I'm sorry that is probably so poorly explained!

Many thanks!
 

berkeman

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Welcome to the PF. :smile:

Can you post some pictures? I'm more familiar with pitching machines that have two spinning wheels, but it does look like there are some single wheel pitching machines...

1567977886298.png
 
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and makes for a relatively immobile machine. I was wondering whether I could reduce the size of this wheel and was wondering how this would affect the performance
learn www.google.ru/search?q=angular+speed Another way is to make pneumatic gun.
 

berkeman

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Another way is to make pneumatic gun.
That's a good suggestion, but I think it will produce mostly knuckleballs. Can you say why that would probably be true? What does a spinning wheel pitching machine do that a pneumatic gun machine would not? :smile:
 
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but I think it will produce mostly knuckleballs
wheel can do it too.
What does a spinning wheel pitching machine do that a pneumatic gun machine would not?
gun is good to control elevation. however, this feature can be realized for wheel too. in many cases, wheel has simplest design == i cannot argue it :)
 

berkeman

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wheel can do it too.
Nope. At least not a single-wheel machine. (have you ever played baseball?)

I wonder if the 2-wheel machines use a slightly slower speed on the top wheel to avoid knuckleballs.
 
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berkeman

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wheel can be rebuild to catapult, so no spin will be produced.
That's not how these pitching machines work. You likely have batting cages near you. Time for a road trip! :smile:
 
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That's not how these pitching machines work.
they just kick ball & that kicking can be done in many ways..

1. wheel.
2. spinning blade.
3. slingshot.
4. pneumatic.
5. even acoustic, but it's overkill :)
 

phinds

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they just kick ball & that kicking can be done in many ways..

1. wheel.
2. spinning blade.
3. slingshot.
4. pneumatic.
5. even acoustic, but it's overkill :)
Clearly you do not understand the dynamics of what is being discussed, if you think you can just lump the performance characteristics of a slingshot and a single wheel system. I suggest that for now you quit while you are behind and study the relevant sperical motion and how it specifically affects a baseball before posting any further.
 

phinds

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@dilby think about what you have to do with a smaller wheel to achieve the same exit speed as with a larger wheel, how long the ball will be in contact with the wheel in each case, and what will be the difference in the dynamics of the ball between the two.
 

berkeman

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they just kick ball & that kicking can be done in many ways..
No. Like I suggested, you probably have not actually played this sport. That's fine, but please don't mislead the OP into thinking that your advice is good. Thanks.
 

jrmichler

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In short, a ball rolls down a tube that is slightly intersected with a large spinning wheel, which has a speed control. The ball brushes this wheel and is projected out. The wheel itself is quite large (30cm), and makes for a relatively immobile machine. I was wondering whether I could reduce the size of this wheel and was wondering how this would affect the performance. (Also other factors i imagine might be the wheel's speed and even perhaps width). So are there principles out there that anyone knows of that I can be pointed in the direction of?
If all you want is a general understanding so that you can play "what if", then the ESP method works very well. ESP, in this case, stands for Exaggeration of System Parameters. Make three sketches:

Sketch 1 is a simplified sketch of your machine - a 7 cm diameter ball, a 30 cm wheel, and the backplate that supports the ball.

Sketch 2 is a similar sketch, except make the wheel about 3 cm, or better, 1 cm diameter. Visualize how the ball approaches the wheel, and is pushed through the machine. Notice the similarities and differences from Sketch 1.

Sketch 3 is a similar sketch, except make the wheel about 300 cm diameter. You only need to show a small portion of the wheel. Visualize how the ball approaches the wheel, and is pushed through the machine. Notice the similarities and differences from Sketches 1 and 2. Also study Post #11.

Think about what happens when the ball first touches the wheel, what happens when the wheel makes firm contact with the ball, and the effect of small changes in ball diameter. Think about the performance, the size of the machine, and the relative cost of the machine.
 

DEvens

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Hmm... 1 wheel, 2 wheel, even 3 wheel. Curves, fastballs, sliders, knuckle balls, even left or right handed for some models. It seems to be heavily dependent on attachments and adjustments. It might be a lot of fun to go examine one of these things in operation. I wonder if there's something near me that has such a thing.

 

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