OK so I only need the ball to go 6 feet (ping pong table) and be fairly accurate. And really would be best to be able to play with spins.

Is this too much to ask? idk. tell me if I should continue to look into it?
http://www.newgy.com/

 

We now know that a ping ball can be shot 35 ft with reasonable accuracy via the " proof of concept model" For spin control need to move on to two motor pitcher with individual speed control. Might also want to be able to change the angle between the wheels. A power darlington transistor with heat sink and pot makes a simple speed control for small motors. With a tac output on each motor, one motor can be slaved to the other allowing for vernier control of differential speed while independently controlling master motors speed.

 

How far you want to go is up to you. If you are willing to put forth the effort and $ , we will stick with you with suggestions and schematics to the best of our abilities. Looks like it may be a long project to develope a ping pong pitching robot- but as a start here's a simple speed control. It would be better if a comercial 24-30 V DC powersupply was used, depending on motors used. G numbers reffer to " The Electronic Goldmine" stock numbers. The transistor, Q1, needs a heat sink of about 4" X 4" X 1/8" aluminum equivalent. That is one advantage of pulse width modulation, PWM, as Q1 would be fully on or off, reducing heat disipation.

 

Here is another version using the G17287 motors [ strobe: small white +5V, brown neg, green 50% duty 6PPR full amplitude square wave output ]. Wheels are 3/4" ply with 3/8" foam tires, effective circumference is one foot. Proposed that sound of ball striking oponents court would trigger solenoid S, injecting a ball between wheels. Problem arose when using balls of different mfg,Halex & Champro differ by 2+ mm.making pressure setting of snubber iffey- Halex sailed thru & fired in salvo.Back to drawing board. Discovering that the motor shaft was only2.75mm dia , two MRC 34 bearings were installed on end of worm gears. Distance 25+ ft on 12V DC.

 

4th try to upload thumbnail.
Looks like we picked up an old sketch for free.

 

Problem solved, firing solenoid [4Ω ] with 3300μF cap @ 30V with snubber removed, spring retainer added [ SS .25mm X 8mm X 95mm ]. Added foot plate. New balls compress foam 1/8", old smaller balls do not shoot as far because of less grip. Now what to do with tac.

 

Hi i am trying to make a tennis ball machine for a school project. I am going to use counter rotating wheels. i have tested using 2 240 power drills mounted and they fire the ball out however the ball doesn't go as fast or as far as i need. What kind of cheap motor do i need to power 2 counter rotating wheels strong enough to give some speed and distance on the ball? and do i need two motors or can i just use one? please help! any ideas about making this machine will be much appreciated
thanks

 

No science- just thinking outloud: For 60 mph launch with 1 ft circumfrence wheels will need about 5,000 RPM. Inertia supplies most of the power so wheels 5 to 10 times as heavy as a ball might work. Inertia of armatures also counts. Motors, 12 to 25 W, need to be rugged to stand side shock load ie shafts 1/4 in or better, or bearing suported on both side of wheels. For tennis, would go for 6 to 8 in dia wheels with compressable tires.

 

Electronic Goldmime # G 17154 has a small brute with proported 1 in by .32 in shaft for US $ 4.00. Reversable ??
' just called Goldmine and they say it is reversable. I would use two motors.
The motor # should be G17454, # appears both ways in ad, TEG was notified of error.