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Makers and Making: Baseball/Softball pitching machine?
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Jan 27th 2008 edited
Hi gents,
been reading this thread for a while, i am very interested in making my own baseball pitching machine after looking at ridiculous prices for manufactured ones.
i play baseball local to me and practice only happens once a week and rarely get more than 20 hits in a session so a machine is much needed to improve my game.
i have ordered several items of kit in the past and spotted these jugs parts for sale on a dutch baseball gear suppliers website.
www.forelle.com
i cant link directly but if you look at baseball/softball> trainings equipment>Accessories you can see some parts available from jugs including a wheel, control and motor separatley.
i dont know how much the items would cost but hopefully it will be a reasonable cost and maybe something that could be reverse engineered.
i need to save up some cash to start my project and will keep an eye on my feeds for updates to this thread.
Also heres an alternative pitching/bowling machine, maybe some tips or info could be found for UK builders(look at bola user manual)
www.bola.co.uk
Good luck all
cheers
jason
been reading this thread for a while, i am very interested in making my own baseball pitching machine after looking at ridiculous prices for manufactured ones.
i play baseball local to me and practice only happens once a week and rarely get more than 20 hits in a session so a machine is much needed to improve my game.
i have ordered several items of kit in the past and spotted these jugs parts for sale on a dutch baseball gear suppliers website.
www.forelle.com
i cant link directly but if you look at baseball/softball> trainings equipment>Accessories you can see some parts available from jugs including a wheel, control and motor separatley.
i dont know how much the items would cost but hopefully it will be a reasonable cost and maybe something that could be reverse engineered.
i need to save up some cash to start my project and will keep an eye on my feeds for updates to this thread.
Also heres an alternative pitching/bowling machine, maybe some tips or info could be found for UK builders(look at bola user manual)
www.bola.co.uk
Good luck all
cheers
jason
Jan 29th 2008
Hi Tim
Sorry for the delay in replying. I have just returned from a ski trip to Borovets, Bulgaria. My home is a complete mess at the moment.
Thank you for your further research. I will try and do the tests this weekend, but have ordered some pots anyway. (Bag of 20 from ebay as it is just as cheap as buying one with postage).
Andy
Sorry for the delay in replying. I have just returned from a ski trip to Borovets, Bulgaria. My home is a complete mess at the moment.
Thank you for your further research. I will try and do the tests this weekend, but have ordered some pots anyway. (Bag of 20 from ebay as it is just as cheap as buying one with postage).
Andy
Jan 31st 2008 edited
Pots arrived today, so made a bit of time for testing as the weekend could be busy.
With the hand throttle closed I got a reading of 4.23v. As I opened the throttle, the motor started at 3.21v and hit full speed at 0.85v (that’s if I’m doing it correctly, but sounds about right I think.)
There was no 10k in the bag of pots, so started with 22k. This altered the speed, but with only a small movement range on the pot, approx 70 degrees. I tried a 470 ohm next (there was a 4k7 but it was a log pot) and this altered the speed over a 180 degree turn approximately.
I turned this pot until the motor just started and took a reading which was around 300 ohms. At 47 ohms, the motor hit full speed.
There are two 470 ohm pots in the bag so I probably use these. I think a 350 ohm pot would be better to get closer to the 270 degree movement, but I do not think they are made with this value.
But all in all, a good result! Thank you, Tim.
With the hand throttle closed I got a reading of 4.23v. As I opened the throttle, the motor started at 3.21v and hit full speed at 0.85v (that’s if I’m doing it correctly, but sounds about right I think.)
There was no 10k in the bag of pots, so started with 22k. This altered the speed, but with only a small movement range on the pot, approx 70 degrees. I tried a 470 ohm next (there was a 4k7 but it was a log pot) and this altered the speed over a 180 degree turn approximately.
I turned this pot until the motor just started and took a reading which was around 300 ohms. At 47 ohms, the motor hit full speed.
There are two 470 ohm pots in the bag so I probably use these. I think a 350 ohm pot would be better to get closer to the 270 degree movement, but I do not think they are made with this value.
But all in all, a good result! Thank you, Tim.
Jan 31st 2008
Cool! I just happened to see you posted a few minutes ago Andy.
You might want to measure the voltage on the "output" line of the pot as you're testing it. You should see similar voltages causing similar motor speeds as you saw from the hand throttle.
Judging from your figures above, 300 ohms for a 470 ohm pot on a 5v line should be 300 / 470 * 5 = 3.2V Hey that's the same as the hand throttle!
At the other end it's 47 / 470 * 5 = 0.5V. That's in the ball park!
I'm not sure why a higher ohm pot didn't work. My only guess is that at higher resistances the voltage isn't held very "firmly" on the output. I'm applying some intuition to the physics of electricity, so that might not make any sense.
You might want to be careful about going too low in the pot ohms. Let's see, 5 V over 470 ohms is 5/470 = 0.011 Amps or 11 mA. Actuually that's fine. I think it's 5 * 11 = 55mWatts. I took a quick look at a list of pots at jameco for reference, and most were 1/2 watt, but even a 1/5th watt potentiometer could handle up to 200mWatt. 470 is probably a good choice, and I wouldn't worry too much unless you go down to 100ohms or less.
I'm glad it's working both for your project and for anyone else who might be looking to find a motor controller.
Thanks for the update! Glad to see something is making sense!
You might want to measure the voltage on the "output" line of the pot as you're testing it. You should see similar voltages causing similar motor speeds as you saw from the hand throttle.
Judging from your figures above, 300 ohms for a 470 ohm pot on a 5v line should be 300 / 470 * 5 = 3.2V Hey that's the same as the hand throttle!
At the other end it's 47 / 470 * 5 = 0.5V. That's in the ball park!
I'm not sure why a higher ohm pot didn't work. My only guess is that at higher resistances the voltage isn't held very "firmly" on the output. I'm applying some intuition to the physics of electricity, so that might not make any sense.
You might want to be careful about going too low in the pot ohms. Let's see, 5 V over 470 ohms is 5/470 = 0.011 Amps or 11 mA. Actuually that's fine. I think it's 5 * 11 = 55mWatts. I took a quick look at a list of pots at jameco for reference, and most were 1/2 watt, but even a 1/5th watt potentiometer could handle up to 200mWatt. 470 is probably a good choice, and I wouldn't worry too much unless you go down to 100ohms or less.
I'm glad it's working both for your project and for anyone else who might be looking to find a motor controller.
Thanks for the update! Glad to see something is making sense!
Jan 31st 2008
One follow on thought. You might have better success placing other resistors in parallel with the pot inorder to increase the usable portion of the pot's rotation.
Lets see if I can illustrate:
gnd--/\/\/\/\/\--o/\/\/\o/\/\/\o--/\/\/\/\/\--5v
each /\/\/\/\/\ is a resistor
The o/\/\/\o/\/\/\o is the pot, with the center 'o' as the "output"
You should be able to adjust the resistors on both sides of the pot so that the output of the pot goes from 0.5v to 3.2v over the entire sweep of the pot. At least you should be able to move in that direction.
I'd have to play around with some numbers to figure out what resistors to recommend on both sides, and I don't have time right now. Perhaps tomorrow if you haven't already figured it out.
-Tim
Lets see if I can illustrate:
gnd--/\/\/\/\/\--o/\/\/\o/\/\/\o--/\/\/\/\/\--5v
each /\/\/\/\/\ is a resistor
The o/\/\/\o/\/\/\o is the pot, with the center 'o' as the "output"
You should be able to adjust the resistors on both sides of the pot so that the output of the pot goes from 0.5v to 3.2v over the entire sweep of the pot. At least you should be able to move in that direction.
I'd have to play around with some numbers to figure out what resistors to recommend on both sides, and I don't have time right now. Perhaps tomorrow if you haven't already figured it out.
-Tim
Jan 31st 2008
Well I couldn't resist the urge to keep thinking about this, so when I had a break I worked it out.
I think you should try approximately 87 ohms between Gnd and the pot and 313 between the pot and 5V. You probably can't find exactly those values in resistors, but something close should work. For testing you could try using two pots set to those values.
Please let me know how that works!
I think you should try approximately 87 ohms between Gnd and the pot and 313 between the pot and 5V. You probably can't find exactly those values in resistors, but something close should work. For testing you could try using two pots set to those values.
Please let me know how that works!
Feb 2nd 2008 edited
Hi, I thought I'd update you all on my own (slow) progress.
I've been focusing on the controls lately. So that has been building some of the circuits around the microcontroller to handle the motor power and RPM sensing. The motor circuit is basically the same MOSFET circuit I've linked to before. I have also added a second MOSFET to provide a breaking mode. All off that has been working out well with smaller 12v motors for testing and a wireless breadboard to build the circuit.
To sense the RPM I'm using an IR phototransistor with a built in LED emittor. When something reflective, like a bit of aluminum foil, is in front of it, the IR light from the LED bounces back on the phototransistor which provides a signal for the microcontroller. I have one peice of foil attached to the side of the wheel, so the microcontroller gets a signal once per revolution.
The reason I'm sensing the motor RPM is I want to have better control over the speed. I suspect the vast majority of machines don't do this, so it's not critical. However, I've found that the wheel speed, and thus ball speed can vary significantly as the machine is used. As each ball is thrown, the motors are slowed down, and then speed back up again to eventually reach the "equilibrium" speed for the power setting. But if the balls are thrown fairly often, like once every 4 seconds, the motor doesn't reach equilibrium speed, but as fast as it gets to in 4 seconds of recovery. Thus if the recovery time is not always the same (e.g., if the ball feeder skips) the ball speed will vary.
So with RPM sensing I can provide feedback to the microcontroller, and to recover the speed faster I can provide more power temporarily. I'm using an approach called PID to use the feedback to control the motor power. If you're interested, you can read an article I found very helpful called <a href="http://www.embedded.com/2000/0010/0010feat3.htm">PID without a PhD</a>
After a fair amount of trial and debugging, I've gotten it to work pretty well. The following graph shows a test.
<center><a href="http://www.flickr.com/photos/76392020@N00/2236610873/" title="PID vs Set Power by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2168/2236610873_da5c22168a_o.gif" width="436" height="286" alt="PID vs Set Power" /></a></center>
The red line is what happens if I start with a stopped motor and just set the power to 142 (out of 255) and hold it there. After about 3 seconds, the motor reaches 3,000 RPM. The blue line is starting from zero and telling the PID controller to take the motor to 3,000 RPM. The PID controller gets there in about 0.7 seconds, although it does overshoot a little.
I'm pretty happy with the results so far.
I have a few more parts of the electronics to build out as a test on the breadboard. The main pieces are interfacing to an hbridge IC to power the elevation and sweep motors (should be straightforward) and sensors for elevation and sweep position. After learning more about Hall efect sensors via Andy, I'm thinking I might actually try that for those position sensors. I may try to build a little sliding contraption that moves a magnet back and forth past a Hall sensor as the machine changes the sweep and elevation position. I'm thinking that might work out better than my previous idea of linear (back and forth slider) pots.
Once I work out those details in the electronics, I'll try to design the whole circuit and make a DIY printed circuit board (PCB).
Again, progress has been slow, but there is progress! I hope to have something pretty solid by Spring.
I've been focusing on the controls lately. So that has been building some of the circuits around the microcontroller to handle the motor power and RPM sensing. The motor circuit is basically the same MOSFET circuit I've linked to before. I have also added a second MOSFET to provide a breaking mode. All off that has been working out well with smaller 12v motors for testing and a wireless breadboard to build the circuit.
To sense the RPM I'm using an IR phototransistor with a built in LED emittor. When something reflective, like a bit of aluminum foil, is in front of it, the IR light from the LED bounces back on the phototransistor which provides a signal for the microcontroller. I have one peice of foil attached to the side of the wheel, so the microcontroller gets a signal once per revolution.
The reason I'm sensing the motor RPM is I want to have better control over the speed. I suspect the vast majority of machines don't do this, so it's not critical. However, I've found that the wheel speed, and thus ball speed can vary significantly as the machine is used. As each ball is thrown, the motors are slowed down, and then speed back up again to eventually reach the "equilibrium" speed for the power setting. But if the balls are thrown fairly often, like once every 4 seconds, the motor doesn't reach equilibrium speed, but as fast as it gets to in 4 seconds of recovery. Thus if the recovery time is not always the same (e.g., if the ball feeder skips) the ball speed will vary.
So with RPM sensing I can provide feedback to the microcontroller, and to recover the speed faster I can provide more power temporarily. I'm using an approach called PID to use the feedback to control the motor power. If you're interested, you can read an article I found very helpful called <a href="http://www.embedded.com/2000/0010/0010feat3.htm">PID without a PhD</a>
After a fair amount of trial and debugging, I've gotten it to work pretty well. The following graph shows a test.
<center><a href="http://www.flickr.com/photos/76392020@N00/2236610873/" title="PID vs Set Power by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2168/2236610873_da5c22168a_o.gif" width="436" height="286" alt="PID vs Set Power" /></a></center>
The red line is what happens if I start with a stopped motor and just set the power to 142 (out of 255) and hold it there. After about 3 seconds, the motor reaches 3,000 RPM. The blue line is starting from zero and telling the PID controller to take the motor to 3,000 RPM. The PID controller gets there in about 0.7 seconds, although it does overshoot a little.
I'm pretty happy with the results so far.
I have a few more parts of the electronics to build out as a test on the breadboard. The main pieces are interfacing to an hbridge IC to power the elevation and sweep motors (should be straightforward) and sensors for elevation and sweep position. After learning more about Hall efect sensors via Andy, I'm thinking I might actually try that for those position sensors. I may try to build a little sliding contraption that moves a magnet back and forth past a Hall sensor as the machine changes the sweep and elevation position. I'm thinking that might work out better than my previous idea of linear (back and forth slider) pots.
Once I work out those details in the electronics, I'll try to design the whole circuit and make a DIY printed circuit board (PCB).
Again, progress has been slow, but there is progress! I hope to have something pretty solid by Spring.
Feb 3rd 2008 edited
Clever idea, Tim. That sort of thing never occurred to me. Are you still going to use the carousel to control the ball feed or are you going to eventually use a device to push the ball into the drive wheels at the most suitable or required time? I was looking at solenoid type devices, but the “travel” (I can’t remember the proper term) of such a device is not very far and not enough to move the ball into the wheels. But, such a device attached to a lever might work.
I’ve managed to do a bit more with the pots, though all very rushed. Terrible weekend. I spent a bit of time attaching wires and croc clips to the pots.
(Hmm- bad link. Copy and paste job)
http://www.flickr.com/photos/21505629@N07/2239023321/in/set-72157603658480754/
I have no doubt that you will groan and shake your head after viewing the photo, Tim, as you strike me as being someone who is neat and particular in their work.
But the good news is your idea works, only the opposite way to your calculations. It worked with the lower resistance on the + and the higher resistance connected to the ground. I used the 470 ohm pot and the 22k pot, being the two lowest I have, as the test resistors and tweaked them until I got the full 270 degree turn on the control pot. The ground pot extends the low speed and the + pot the top end speed. (Does this make sense to you?) I then dismantled the cables and took the resistance readings of the pots. Your calculations were pretty much spot on.
Unfortunately the pots are a bit too cheap and cheerful. As the control pot approaches its minimum resistance (or max motor speed), the motor started cutting out as though there is a bad connection. The other 470 ohm pot is actually a 515 ohm one.
As for voltage readings, it is more or less from 3.31v to 0.6v “output” and 5.06 to 4.7v + to gnd.
So, just need to get some decent pots and a couple of resistors.
My friend still hasn’t got around to drilling the bolts yet. I’m off to Thailand next week for a couple of weeks, so if he hasn’t managed to do them by the time I return, I think I’ll have to get a mini lathe.
Andy.
I’ve managed to do a bit more with the pots, though all very rushed. Terrible weekend. I spent a bit of time attaching wires and croc clips to the pots.
(Hmm- bad link. Copy and paste job)
http://www.flickr.com/photos/21505629@N07/2239023321/in/set-72157603658480754/
I have no doubt that you will groan and shake your head after viewing the photo, Tim, as you strike me as being someone who is neat and particular in their work.
But the good news is your idea works, only the opposite way to your calculations. It worked with the lower resistance on the + and the higher resistance connected to the ground. I used the 470 ohm pot and the 22k pot, being the two lowest I have, as the test resistors and tweaked them until I got the full 270 degree turn on the control pot. The ground pot extends the low speed and the + pot the top end speed. (Does this make sense to you?) I then dismantled the cables and took the resistance readings of the pots. Your calculations were pretty much spot on.
Unfortunately the pots are a bit too cheap and cheerful. As the control pot approaches its minimum resistance (or max motor speed), the motor started cutting out as though there is a bad connection. The other 470 ohm pot is actually a 515 ohm one.
As for voltage readings, it is more or less from 3.31v to 0.6v “output” and 5.06 to 4.7v + to gnd.
So, just need to get some decent pots and a couple of resistors.
My friend still hasn’t got around to drilling the bolts yet. I’m off to Thailand next week for a couple of weeks, so if he hasn’t managed to do them by the time I return, I think I’ll have to get a mini lathe.
Andy.
Feb 4th 2008
Hi Andy,
Yes, I'm still planning to use the carousel. It seems to be working decently. My problems are more about skipping balls, and some jamming. Once the balls get through the carousel, rolling down the tube and getting to the wheels with gravity is working okay.
I realized last night that positioning a sensor to know when a ball is in position and ready to drop (when I turn the carousel back on) is going to be tricky. I have some sensors from an old laser printer I stripped, but it's not going to be easy to find a place for one.
I previously tried to work out the machanics for a solenoid that would shift a collar back and forth to release one ball at a time. I also had lots of problems with solenoids. The stroke/travel was pretty short, and they weren't very strong. So I gave up and went with the carousel.
I'll post a picture of my work area and you'll feel much better about yours and have a different opinion about my neatness habits!
Glad the additional resistors/pots theory worked. I don't understand how I got it backwards, but your empirical results trump my theory!
If you end up using a different (than 470 ohms) pot for the speed control, you'll have to adjust the values of the resistors on either side too. If you haven't picked up on this, the basic idea is a voltage divider, which you can read about in <a href="http://en.wikipedia.org/wiki/Voltage_divider">this Wikipedia entry</a>, and I can explain it some more too. Or you can use pots to find values that work.
Good luck getting your friend drilling! I've been prompted to purchase some tools for this project, but I haven't gone so far as a lathe! I'd love to have access to one though.
Yes, I'm still planning to use the carousel. It seems to be working decently. My problems are more about skipping balls, and some jamming. Once the balls get through the carousel, rolling down the tube and getting to the wheels with gravity is working okay.
I realized last night that positioning a sensor to know when a ball is in position and ready to drop (when I turn the carousel back on) is going to be tricky. I have some sensors from an old laser printer I stripped, but it's not going to be easy to find a place for one.
I previously tried to work out the machanics for a solenoid that would shift a collar back and forth to release one ball at a time. I also had lots of problems with solenoids. The stroke/travel was pretty short, and they weren't very strong. So I gave up and went with the carousel.
I'll post a picture of my work area and you'll feel much better about yours and have a different opinion about my neatness habits!
Glad the additional resistors/pots theory worked. I don't understand how I got it backwards, but your empirical results trump my theory!
If you end up using a different (than 470 ohms) pot for the speed control, you'll have to adjust the values of the resistors on either side too. If you haven't picked up on this, the basic idea is a voltage divider, which you can read about in <a href="http://en.wikipedia.org/wiki/Voltage_divider">this Wikipedia entry</a>, and I can explain it some more too. Or you can use pots to find values that work.
Good luck getting your friend drilling! I've been prompted to purchase some tools for this project, but I haven't gone so far as a lathe! I'd love to have access to one though.
Feb 5th 2008
Andy,
Since you brought it up again, I'm rethinking the carousel idea. I'm wondering if I could get something that releases an individual ball on cue, more along the lines of something that might use a solenoid (back and forth movement), but using a gearmotor for greater power. Hmmm... I 'll keep thinking about it.
-Tim
Since you brought it up again, I'm rethinking the carousel idea. I'm wondering if I could get something that releases an individual ball on cue, more along the lines of something that might use a solenoid (back and forth movement), but using a gearmotor for greater power. Hmmm... I 'll keep thinking about it.
-Tim
Feb 6th 2008
Tim
With a system like yours I'd have thought you would stack the balls behind the propulsion wheels and just prod them forward when the time is right. There is a bit of a delay between the carousel and the wheels.
Off to airport now. I'll catch up in a couple of weeks.
With a system like yours I'd have thought you would stack the balls behind the propulsion wheels and just prod them forward when the time is right. There is a bit of a delay between the carousel and the wheels.
Off to airport now. I'll catch up in a couple of weeks.
Feb 6th 2008
Andy,
I've thought of such a prodding approach, but I can't visualize a good way to do it. There is a delay from the carousel to the wheels, but I'm thinking I can build that into the programming, so the ball is released from the carousel a bit before it's actually supposed to be thrown.
Have a good trip.
-Tim
I've thought of such a prodding approach, but I can't visualize a good way to do it. There is a delay from the carousel to the wheels, but I'm thinking I can build that into the programming, so the ball is released from the carousel a bit before it's actually supposed to be thrown.
Have a good trip.
-Tim
Mar 9th 2008 edited
It’s all very quiet on here.
This weekend I have started making the TBM frame. I have also managed to build most of the carousel, based on Tim’s one.
(Bad link as usual. Please copy and paste to view)
http://www.flickr.com/photos/21505629@N07/sets/72157603658480754/
Fortunately I don’t have to fit the TBM in the back of a car, so plenty of space to play with. I have ordered two bearings for the carousel, the pots and resistors for the e-scooter motor controllers and decided to get two more motor controllers for the carousel and forehand/backhand oscillator. The two extra controllers are for the Molon gear motors which draw only a small current so weren’t expensive. Also ordered a few switches.
Tim, I am looking at the following remote control receiver to connect to the carousel motor so the balls are started when I am ready.
http://www.quasarelectronics.com/3058.htm
Have you got anything like this on your TBM? I have enquired about the range from transmitter to receiver from Quasar, so waiting to hear. Whether it will be any good or not, I don’t know.
Thinking of the ball prodding device, a rack and pinion set up with a stepper motor might work as motor can be accurately controlled by your microcontroller.
http://catalog.orientalmotor.com/viewitems/linear-motion--1080/lh-series-linear-heads?&forward=1
The above examples are a horrendous price and the fastest not exactly speedy (build more for torque I think), but you may be able to rig your own up. But, as you say, allowing for the delay sounds a good option.
Still no sign of the drive wheels and bolts. My friend said he will try as soon as possible to get them done. I have thought again about a lathe, but it is hard to justify buying one when I am not sure what future projects it can be used for. Also to do the wheels requires a big lathe with a 200mm+ swing-over-bed clearance (£600+), or a small metal lathe AND a wood lathe.
This weekend I have started making the TBM frame. I have also managed to build most of the carousel, based on Tim’s one.
(Bad link as usual. Please copy and paste to view)
http://www.flickr.com/photos/21505629@N07/sets/72157603658480754/
Fortunately I don’t have to fit the TBM in the back of a car, so plenty of space to play with. I have ordered two bearings for the carousel, the pots and resistors for the e-scooter motor controllers and decided to get two more motor controllers for the carousel and forehand/backhand oscillator. The two extra controllers are for the Molon gear motors which draw only a small current so weren’t expensive. Also ordered a few switches.
Tim, I am looking at the following remote control receiver to connect to the carousel motor so the balls are started when I am ready.
http://www.quasarelectronics.com/3058.htm
Have you got anything like this on your TBM? I have enquired about the range from transmitter to receiver from Quasar, so waiting to hear. Whether it will be any good or not, I don’t know.
Thinking of the ball prodding device, a rack and pinion set up with a stepper motor might work as motor can be accurately controlled by your microcontroller.
http://catalog.orientalmotor.com/viewitems/linear-motion--1080/lh-series-linear-heads?&forward=1
The above examples are a horrendous price and the fastest not exactly speedy (build more for torque I think), but you may be able to rig your own up. But, as you say, allowing for the delay sounds a good option.
Still no sign of the drive wheels and bolts. My friend said he will try as soon as possible to get them done. I have thought again about a lathe, but it is hard to justify buying one when I am not sure what future projects it can be used for. Also to do the wheels requires a big lathe with a 200mm+ swing-over-bed clearance (£600+), or a small metal lathe AND a wood lathe.
Mar 9th 2008
Hi Andy!
Nice pictures! It's funny for me to see the similar carousel, but out of wood. Those wheels look handy too! I commandeered my children's wagon, clamping mine on top!
There hasn't been much activity here, but I still check it a few times a day. Nice to hear about your progress and thoughts. I've been getting decent time on my machine. Lately I've been adding poteniometers that get turned to sense position when the sweep or elevation changes. It's amazing how long it takes me to make up the little bits of metal that hold them in place or and arm that gets pushed to turn them. I'll try to post some pictures this week.
I was also working some more on attaching the threaded rod to my motors that change the sweep and elevation. I had a new idea to get the rod attachment straight and centered. That is to file down about an inch at one end of the rod to the same diameter as the motor shaft, then put both the motor shaft and the end of the rod in the same hold drilled through another shaft (a cut off bolt actually). I hope that's clear enough. I clamped down a hand drill to spin the rod with a bushing held near the other end to make a crude lathe-like thing. It worked decently, but I might try it again to see if practice helps. The motors have a tolerable amount of vibration, but I'd still like less.
I've also been rethinking my carousel, so I'm interested to hear how yours is going. I think I might be able to tweak mine to work okay with less skipping. I think part of my trouble is that it spins too fast and doesn't have sloping sides around it that are steep enough. It spins kind of fast because I wanted to have shots up to 1 per second, but that might be excessive.
I don't have any remote yet, but I'd been thinking of an rc keyfob-like thing. I've seen them, but couldn't find one quickly to link to now.
That rack and pinion stuff does look expensive, but I'll have to see if it gives me any ideas. I originally thought about a stepper motor, but I think most are not nearly strong enough / fast enough for this job. But I could be wrong.Good luck
-Tim
Nice pictures! It's funny for me to see the similar carousel, but out of wood. Those wheels look handy too! I commandeered my children's wagon, clamping mine on top!
There hasn't been much activity here, but I still check it a few times a day. Nice to hear about your progress and thoughts. I've been getting decent time on my machine. Lately I've been adding poteniometers that get turned to sense position when the sweep or elevation changes. It's amazing how long it takes me to make up the little bits of metal that hold them in place or and arm that gets pushed to turn them. I'll try to post some pictures this week.
I was also working some more on attaching the threaded rod to my motors that change the sweep and elevation. I had a new idea to get the rod attachment straight and centered. That is to file down about an inch at one end of the rod to the same diameter as the motor shaft, then put both the motor shaft and the end of the rod in the same hold drilled through another shaft (a cut off bolt actually). I hope that's clear enough. I clamped down a hand drill to spin the rod with a bushing held near the other end to make a crude lathe-like thing. It worked decently, but I might try it again to see if practice helps. The motors have a tolerable amount of vibration, but I'd still like less.
I've also been rethinking my carousel, so I'm interested to hear how yours is going. I think I might be able to tweak mine to work okay with less skipping. I think part of my trouble is that it spins too fast and doesn't have sloping sides around it that are steep enough. It spins kind of fast because I wanted to have shots up to 1 per second, but that might be excessive.
I don't have any remote yet, but I'd been thinking of an rc keyfob-like thing. I've seen them, but couldn't find one quickly to link to now.
That rack and pinion stuff does look expensive, but I'll have to see if it gives me any ideas. I originally thought about a stepper motor, but I think most are not nearly strong enough / fast enough for this job. But I could be wrong.Good luck
-Tim
Mar 16th 2008
Tim
I haven’t done much this week. The bits and pieces I ordered arrived about mid week so I’ve managed to mount the carousel on another chunk of kitchen worktop using the small bearings. It’s a bit rough and ready and doesn’t rotate dead evenly but I think it will be alright. As the carousel rotated, though, the balls were snagging on the plywood and not rolling causing a lot of drag so it is not the best material to use. I have got round this by putting plastic sleeves made from 3”pipe into the slots. I’ve put a pic on Flickr.
At the moment I am trying to join the carousel shaft to the Molon motor shaft. Both are 8mm but for some reason suppliers only seem to sell shaft couplers up to 6mm. I’ve drilled out an 8mm nut and tapped the side with a 4mm bolt for the motor shaft, so I’ll weld it to another 8mm nut on the carousel shaft next time. I know what you mean about small bits taking a long time.
I’m still working out how to do the ball hopper. With next week being Easter I might be able to get something up and running, depending how busy things are on the camp site.
The idea with the potentiometers sounds good. It’ll be interesting to see the photos.
Andy
I haven’t done much this week. The bits and pieces I ordered arrived about mid week so I’ve managed to mount the carousel on another chunk of kitchen worktop using the small bearings. It’s a bit rough and ready and doesn’t rotate dead evenly but I think it will be alright. As the carousel rotated, though, the balls were snagging on the plywood and not rolling causing a lot of drag so it is not the best material to use. I have got round this by putting plastic sleeves made from 3”pipe into the slots. I’ve put a pic on Flickr.
At the moment I am trying to join the carousel shaft to the Molon motor shaft. Both are 8mm but for some reason suppliers only seem to sell shaft couplers up to 6mm. I’ve drilled out an 8mm nut and tapped the side with a 4mm bolt for the motor shaft, so I’ll weld it to another 8mm nut on the carousel shaft next time. I know what you mean about small bits taking a long time.
I’m still working out how to do the ball hopper. With next week being Easter I might be able to get something up and running, depending how busy things are on the camp site.
The idea with the potentiometers sounds good. It’ll be interesting to see the photos.
Andy
Mar 16th 2008
Hi Andy,
Good luck with the carousel. I also got the sense that slippery was good to keep the balls from jaming. I considered 3" PVC inserts too! Sounds like with the drilling, tapping, and welding that you're working things out pretty well.
I didn't get much time to work on my machine this week or weekend, but I did manage to take some pictures.
Here's picture of my drill press set up to cut a slot in an arm I use to turn the potentiometer that senses the sweep position.
<a href="http://www.flickr.com/photos/76392020@N00/2338491905/" title="Cutting Pot Arm by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2233/2338491905_b07433d6fe_m.jpg" width="240" height="160" alt="Cutting Pot Arm" /></a>
I put a dremel cutoff wheel in my drill press and an x-y sliding vise to hold the arm and move it into the cutting wheel. This arm was a cut off part of a bolt to begin with.
Here are two pictures of it mounted in place.
<a href="http://www.flickr.com/photos/76392020@N00/2338491481/" title="Sweep Pot II by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2014/2338491481_630a1e10d0_m.jpg" width="240" height="160" alt="Sweep Pot II" /></a>
<a href="http://www.flickr.com/photos/76392020@N00/2338491601/" title="Sweep Pot 1 by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2341/2338491601_88438c53c6_m.jpg" width="240" height="160" alt="Sweep Pot 1" /></a>
I would have mounted this pot in line with the pivot point (hinge) that the base swings back and forth around when it sweeps, but there wasn't room. So I worked out this system with the arm.
Lastly, here's the poteniometer that senses the elevation.
<a href="http://www.flickr.com/photos/76392020@N00/2339324684/" title="Elevation Pot by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2404/2339324684_a6d379af66_m.jpg" width="240" height="160" alt="Elevation Pot" /></a>
That's another cut off bolt as the arm. I taped a whole for a set screw, and a couple more to attached it to a bar that is attached to the base.
These potentiometers will vary a voltage, whicn will be measured by an analog to digital converter (ADC) in the microcontroller. It looks like I'll get about 100 points of resolution in the the sweep position sensor. That is the ADC output will vary from 1 to 100 over the range of the sweep position. That's plenty of resolution to sense the sweep position, so I think that should work out pretty well.
Good luck with the carousel. I also got the sense that slippery was good to keep the balls from jaming. I considered 3" PVC inserts too! Sounds like with the drilling, tapping, and welding that you're working things out pretty well.
I didn't get much time to work on my machine this week or weekend, but I did manage to take some pictures.
Here's picture of my drill press set up to cut a slot in an arm I use to turn the potentiometer that senses the sweep position.
<a href="http://www.flickr.com/photos/76392020@N00/2338491905/" title="Cutting Pot Arm by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2233/2338491905_b07433d6fe_m.jpg" width="240" height="160" alt="Cutting Pot Arm" /></a>
I put a dremel cutoff wheel in my drill press and an x-y sliding vise to hold the arm and move it into the cutting wheel. This arm was a cut off part of a bolt to begin with.
Here are two pictures of it mounted in place.
<a href="http://www.flickr.com/photos/76392020@N00/2338491481/" title="Sweep Pot II by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2014/2338491481_630a1e10d0_m.jpg" width="240" height="160" alt="Sweep Pot II" /></a>
<a href="http://www.flickr.com/photos/76392020@N00/2338491601/" title="Sweep Pot 1 by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2341/2338491601_88438c53c6_m.jpg" width="240" height="160" alt="Sweep Pot 1" /></a>
I would have mounted this pot in line with the pivot point (hinge) that the base swings back and forth around when it sweeps, but there wasn't room. So I worked out this system with the arm.
Lastly, here's the poteniometer that senses the elevation.
<a href="http://www.flickr.com/photos/76392020@N00/2339324684/" title="Elevation Pot by timwhunt, on Flickr"><img src="http://farm3.static.flickr.com/2404/2339324684_a6d379af66_m.jpg" width="240" height="160" alt="Elevation Pot" /></a>
That's another cut off bolt as the arm. I taped a whole for a set screw, and a couple more to attached it to a bar that is attached to the base.
These potentiometers will vary a voltage, whicn will be measured by an analog to digital converter (ADC) in the microcontroller. It looks like I'll get about 100 points of resolution in the the sweep position sensor. That is the ADC output will vary from 1 to 100 over the range of the sweep position. That's plenty of resolution to sense the sweep position, so I think that should work out pretty well.
Mar 17th 2008
Hello
I just found this the other day. I built a pitching machine using a treadmill motor. It is variable speed and I used the controls from the treadmill to regulate the speed. The best part was that the treadmill was free. If this was stated earilier I am sorry. I did not read it anywhere and thought I would give you my 2 cents.
Jim
I just found this the other day. I built a pitching machine using a treadmill motor. It is variable speed and I used the controls from the treadmill to regulate the speed. The best part was that the treadmill was free. If this was stated earilier I am sorry. I did not read it anywhere and thought I would give you my 2 cents.
Jim
Mar 17th 2008
Hey Jim,
Thanks for chiming in! I'm not sure is anyone proposed treadmill motors, but certainly no one was able to say they got it to work. What kinds of wheels did you use? What kind of RPM did the motor provide, and what sorts of ball speeds did you get? Did you use one or two wheels? Any pictures?
As you can see, lots of questions! It's great to hear of and learn from someone who suceeded.
Regards,
Tim
Thanks for chiming in! I'm not sure is anyone proposed treadmill motors, but certainly no one was able to say they got it to work. What kinds of wheels did you use? What kind of RPM did the motor provide, and what sorts of ball speeds did you get? Did you use one or two wheels? Any pictures?
As you can see, lots of questions! It's great to hear of and learn from someone who suceeded.
Regards,
Tim
Mar 17th 2008
I used a white pitching machine tire like this one: http://www.nebraskatire.com/hot_deals/misc/misc_hot_deals.htm
It does not rip up balls like other tires do.
I only used one wheel. I have used this machine for 2 years now. It produces speeds about 60-65 mph. I will have to see what the RPMs of the motor. It is put away for the winter but i will be getting it oput soon. It cost a total of $75. The only thing i bought was the tire. My son is 12 and it is fast enoght for him. I also made it so it would throw softballs. I know that the picthing machines from the US uses DC Motors and that is why I used the treadmill. Also I wanted to make it variable spped and that was the only way i could think of doing it. I would like to try and make a 2 wheeled machine. I need one more motor and time. I will try to get some pictures. It is not the preetiest thing but it works well.
Jim
It does not rip up balls like other tires do.
I only used one wheel. I have used this machine for 2 years now. It produces speeds about 60-65 mph. I will have to see what the RPMs of the motor. It is put away for the winter but i will be getting it oput soon. It cost a total of $75. The only thing i bought was the tire. My son is 12 and it is fast enoght for him. I also made it so it would throw softballs. I know that the picthing machines from the US uses DC Motors and that is why I used the treadmill. Also I wanted to make it variable spped and that was the only way i could think of doing it. I would like to try and make a 2 wheeled machine. I need one more motor and time. I will try to get some pictures. It is not the preetiest thing but it works well.
Jim
Mar 17th 2008
Oh one more thing, this person used to seel plans to build your own. I know that he does not so it anymore but you can look at his machines. http://savedbygracemachines.com/mighty_one.htm
Jim
Jim
Mar 18th 2008
Jim,
Thanks for the additional info. I was surprised to see the wheel advertised as for a pitching machine. Did it come well balanced?
Did you have any trouble mounting the wheel on the motor? That's seems trickey unless one has a lathe to make an adaptor.
Do you plug yours in to household current (or is it run by battery)?
Pitching machines are a bit different than tennis machines like the one I'm building, but they have important similarities and I can appreciate the accomplishment of building one that works! I'm looking forward to seeing the pictures.
Regards,
Tim
Thanks for the additional info. I was surprised to see the wheel advertised as for a pitching machine. Did it come well balanced?
Did you have any trouble mounting the wheel on the motor? That's seems trickey unless one has a lathe to make an adaptor.
Do you plug yours in to household current (or is it run by battery)?
Pitching machines are a bit different than tennis machines like the one I'm building, but they have important similarities and I can appreciate the accomplishment of building one that works! I'm looking forward to seeing the pictures.
Regards,
Tim
Mar 24th 2008
Tim
The pictures look good. Nice delicate work. Clever stuff.
I managed to connect the Molon motor to the carousel only to find the motor wasn’t strong enough. It turned the carousel okay but quickly stalled when little resistance was applied. So back to the drawing board on that one.
It is getting busy on the camp site so I’ll have less time to work on the TBM. I was hoping to have something usable by now. Never mind.
I’ve tested the small controllers I ordered recently, but for some reason the motors give a high pitched sound when they are not rotating or at low speed. Very strange.
Andy
The pictures look good. Nice delicate work. Clever stuff.
I managed to connect the Molon motor to the carousel only to find the motor wasn’t strong enough. It turned the carousel okay but quickly stalled when little resistance was applied. So back to the drawing board on that one.
It is getting busy on the camp site so I’ll have less time to work on the TBM. I was hoping to have something usable by now. Never mind.
I’ve tested the small controllers I ordered recently, but for some reason the motors give a high pitched sound when they are not rotating or at low speed. Very strange.
Andy
Mar 24th 2008
Thanks Andy,
Sorry to hear the motor wasn't strong enough. Do you have a link handy to where you found it online. I admit I'm being lazy because you probably posted one before, but I'm a little short on time for searching for it. I can't remember, it could even be a motor I used!
I wanted to have mine done about 2 years ago!!
That pitched sound you hear is completely normal. Mine does it too. That's the PWM frequency as the pulses of current cause something in the motor to oscillate. I suspect it's there when it's spinning faster too, but harder to hear with the other noises, Maybe not, I haven't paid close attention.
I've been very busy with work so I haven't had much time on mine.
Good luck!
Tim
Sorry to hear the motor wasn't strong enough. Do you have a link handy to where you found it online. I admit I'm being lazy because you probably posted one before, but I'm a little short on time for searching for it. I can't remember, it could even be a motor I used!
I wanted to have mine done about 2 years ago!!
That pitched sound you hear is completely normal. Mine does it too. That's the PWM frequency as the pulses of current cause something in the motor to oscillate. I suspect it's there when it's spinning faster too, but harder to hear with the other noises, Maybe not, I haven't paid close attention.
I've been very busy with work so I haven't had much time on mine.
Good luck!
Tim
Mar 25th 2008
Hi Tim,
I got the motors from the Surplus Center.
http://www.surpluscenter.com/item.asp?UID=2008011307522906&item=5-1257&catname=electric
Thanks for the information on the new controllers. It had me a bit rattled for a while. The controllers from the e-scooters don’t have this noise.
Andy
I got the motors from the Surplus Center.
http://www.surpluscenter.com/item.asp?UID=2008011307522906&item=5-1257&catname=electric
Thanks for the information on the new controllers. It had me a bit rattled for a while. The controllers from the e-scooters don’t have this noise.
Andy
Mar 25th 2008
Thanks for the link Andy! I'm surprised they don't have enough torque. The listing says "Torque 38 in. lbs. full load", although I suspect that's at 24v and you're probably using them at 12v. Still I would have expected that to be enough torque.
Good luck!
Tim
Good luck!
Tim
Mar 26th 2008
Hello,
I'm currently making a tennis ball machine and was looking around on
the internet for different mechanism to launch the ball`s.... and found you guy`s thats great!
Looking at your forum and the pictures, i have got a hole other perception on it.
I'am using two electric steps cut in half "http://www.stepbridge.nl/images/orangestep.jpg"
and welded together. A good thing about it is that I don`t have
to worry about balance the wheels and mounting the wheels directly on the motor."It uses a belt drive"
The motor I use is a "Torpedo 850 Marine Electric Motor"
it has low TORQUE but high rpm`s.
The wheels of the steps are very light but the tread of the wheels are small about 2,5 cm ~ 1inch
the diameter of the wheelis about 13cm ~ 5inch.
I have tested it and can say little about the speed but it shoots the hole tennis field.
My machine is still far from completion, but in the weekend I will try to post some pic`s.
Thanks,
Willy
I'm currently making a tennis ball machine and was looking around on
the internet for different mechanism to launch the ball`s.... and found you guy`s thats great!
Looking at your forum and the pictures, i have got a hole other perception on it.
I'am using two electric steps cut in half "http://www.stepbridge.nl/images/orangestep.jpg"
and welded together. A good thing about it is that I don`t have
to worry about balance the wheels and mounting the wheels directly on the motor."It uses a belt drive"
The motor I use is a "Torpedo 850 Marine Electric Motor"
it has low TORQUE but high rpm`s.
The wheels of the steps are very light but the tread of the wheels are small about 2,5 cm ~ 1inch
the diameter of the wheelis about 13cm ~ 5inch.
I have tested it and can say little about the speed but it shoots the hole tennis field.
My machine is still far from completion, but in the weekend I will try to post some pic`s.
Thanks,
Willy
Mar 26th 2008
Hi Willy,
I'll be very interested to follow your progress. Parts from scooters (steps) have been considered by several of us. I'm just using batteries from a scooter now, but Andy has experimented with speed controllers.
I'm a little worried that you won't get as much ball speed as you'd like. But if you've tested it and it goes the length of the court, perhaps it's okay. Generally, we're looking for top ball speeds without spin at least 60 miles per hour. (adding spin requires slowing a motor to less than max, so the resulting ball speed is less than max). To get 60 mph ball speed, I'd guess you need the equivalent wheel speed of 70 mph. However, I wouldn't think you'd get such high speeds from the scooters. Of course when you're riding them you can't go nearly that fast, but they could spin the wheels a lot faster when they are just spinning freely.
I'd be curious to hear what your wheel RPM is. Can you try the sound recording approach to measuring your wheel RPM? We've discussed that in this thread, but it's basically putting tape on the wheel, spinning it and letting the tape hit something (like your finger), recording the sound and analyzing the sound file to see how many ticks (tape strikes) per second, etc.
Good luck!
Tim
I'll be very interested to follow your progress. Parts from scooters (steps) have been considered by several of us. I'm just using batteries from a scooter now, but Andy has experimented with speed controllers.
I'm a little worried that you won't get as much ball speed as you'd like. But if you've tested it and it goes the length of the court, perhaps it's okay. Generally, we're looking for top ball speeds without spin at least 60 miles per hour. (adding spin requires slowing a motor to less than max, so the resulting ball speed is less than max). To get 60 mph ball speed, I'd guess you need the equivalent wheel speed of 70 mph. However, I wouldn't think you'd get such high speeds from the scooters. Of course when you're riding them you can't go nearly that fast, but they could spin the wheels a lot faster when they are just spinning freely.
I'd be curious to hear what your wheel RPM is. Can you try the sound recording approach to measuring your wheel RPM? We've discussed that in this thread, but it's basically putting tape on the wheel, spinning it and letting the tape hit something (like your finger), recording the sound and analyzing the sound file to see how many ticks (tape strikes) per second, etc.
Good luck!
Tim
Mar 26th 2008
Hi folks -
I came across your thread while looking for solutions to building a baseball pitching machine. I have been skimming through your ideas and they have given me hope on building one that will replace the one I purchased a year ago. (The wheels disintegrate regularly!).
First off, (and excuse me for getting into baseball pitching machine 101!) I was most interested in those pitching tires that Jim mentioned back on March 17. I'm assuming these tires/wheels are about 4-8 lbs. I'm assuming you guys are using far lighter wheels, but I'm not sure. I did my own review of motors and while most of you guys seem to prefer dc motors, I'm looking into ac motors since most of the ball fields in my area have electrical capabilities. I can get a 1/5 hp motor that can do 10,000 rpms. This motor is from Grainger:
http://www.grainger.com/Grainger/items/2M139?BaseItem=2M037
Since I am a mere "apprentice level" baseball pitcing machine person at this point, I'm wondering what you guys think of this motor and can it handle/spin a tire the size/weight of that pitching tire (8 inches - 4.80-8.0)? I also found this nice controler for the speed of the motor also at grainger:
http://www.grainger.com/Grainger/items/4X796
Any thoughts on these items would be appreciated!
Keith
I came across your thread while looking for solutions to building a baseball pitching machine. I have been skimming through your ideas and they have given me hope on building one that will replace the one I purchased a year ago. (The wheels disintegrate regularly!).
First off, (and excuse me for getting into baseball pitching machine 101!) I was most interested in those pitching tires that Jim mentioned back on March 17. I'm assuming these tires/wheels are about 4-8 lbs. I'm assuming you guys are using far lighter wheels, but I'm not sure. I did my own review of motors and while most of you guys seem to prefer dc motors, I'm looking into ac motors since most of the ball fields in my area have electrical capabilities. I can get a 1/5 hp motor that can do 10,000 rpms. This motor is from Grainger:
http://www.grainger.com/Grainger/items/2M139?BaseItem=2M037
Since I am a mere "apprentice level" baseball pitcing machine person at this point, I'm wondering what you guys think of this motor and can it handle/spin a tire the size/weight of that pitching tire (8 inches - 4.80-8.0)? I also found this nice controler for the speed of the motor also at grainger:
http://www.grainger.com/Grainger/items/4X796
Any thoughts on these items would be appreciated!
Keith
Mar 26th 2008
Hi Tim,
The scooter has a default motor 24v/3000rpm and 16/88 gearing, 5 inch wheels so the spin around 8mph.
Then I changed the gearing to 48/88 ~24.5mph, but when I tested it the ball wasn`t scoothing very far even before the net.
After the test results a decided to use a different the motor the Torpedo 850.
Read from the datasheet 12V, max. 9778rpm
But I don`t think the wheel is realy spinning at that speed, but there spinning rrrealy fast....
For the calculation I used around 8000rpm`s and with the gearing 48/88 that is ~65mph so that`s close to what you calculated.
When I look at the power cunsumtion when the motor is running idle rpm`s it is 5.5Amps so it well with in the spec`s.
I'll keep you posted.
Cheers,
Willy
The scooter has a default motor 24v/3000rpm and 16/88 gearing, 5 inch wheels so the spin around 8mph.
Then I changed the gearing to 48/88 ~24.5mph, but when I tested it the ball wasn`t scoothing very far even before the net.
After the test results a decided to use a different the motor the Torpedo 850.
Read from the datasheet 12V, max. 9778rpm
But I don`t think the wheel is realy spinning at that speed, but there spinning rrrealy fast....
For the calculation I used around 8000rpm`s and with the gearing 48/88 that is ~65mph so that`s close to what you calculated.
When I look at the power cunsumtion when the motor is running idle rpm`s it is 5.5Amps so it well with in the spec`s.
I'll keep you posted.
Cheers,
Willy
Mar 26th 2008
Hi Willy,
That sounds like some good moves and work. Where did you get that motor and any links to info online. Finding motors always seems hard.
Good luck with it, and do keep us posted (with pictures!)
-Tim
That sounds like some good moves and work. Where did you get that motor and any links to info online. Finding motors always seems hard.
Good luck with it, and do keep us posted (with pictures!)
-Tim
Mar 26th 2008
Hi Keith,
I wish I had more informed opinions to offer you on those things. We are using much lighter wheels, and I don't have much sense of what it will take to use heavier ones. I suspect the shaft on that motor is heavy enough, but I don't really know. It's only an inch long, which I guess is okay but you'll need a well made adaptor for it. 10,000 RPM should be much more than you'll need. It's 1/5th horse power, while I think the motors I'm using with the lighter wheels are 1/8th. I think yours would still get to a good top speed, but it might take some time t spin the heavy wheels up to speed and get back to speed after a toss.
I also noticed the motor has sleeve bearings (not ball bearings), which might be fine, but I'd read up on it a bit.
Those Granger parts are going to add up and be kind of expense, especially if you have a two motor/wheel design.
Good luck with it!
-Tim
I wish I had more informed opinions to offer you on those things. We are using much lighter wheels, and I don't have much sense of what it will take to use heavier ones. I suspect the shaft on that motor is heavy enough, but I don't really know. It's only an inch long, which I guess is okay but you'll need a well made adaptor for it. 10,000 RPM should be much more than you'll need. It's 1/5th horse power, while I think the motors I'm using with the lighter wheels are 1/8th. I think yours would still get to a good top speed, but it might take some time t spin the heavy wheels up to speed and get back to speed after a toss.
I also noticed the motor has sleeve bearings (not ball bearings), which might be fine, but I'd read up on it a bit.
Those Granger parts are going to add up and be kind of expense, especially if you have a two motor/wheel design.
Good luck with it!
-Tim
Mar 27th 2008
Tim,
Here is some online info:
http://www1.nl2.conrad.com/scripts/wgate/zcop_nl2/~flNlc3Npb249UDkwX05MX0IyQzpDX0FHQVRFMTE6MDAwMC4wMDY0LmU3YWIyMGRmJn5odHRwX2NvbnRlbnRfY2hhcnNldD1pc28tODg1OS0xJn5TdGF0ZT05NTMyODY0OTg=?~template=PCAT_AREA_S_BROWSE&p_selected_area=%24ROOT&perform_special_action=&glb_user_js=Y&shop=NL2&product_show_id=&p_page_to_display=DirektSearch&~cookies=1&zhmmh_lfo=&zhmmh_area_kz=&s_haupt_kategorie=&p_searchstring=motor+850&p_searchstring_artnr=&r3_matn=&insert_kz=&area_s_url=&area_url=&direkt_aufriss_area=&p_countdown=&p_80=&p_80_category=&p_80_article=&p_next_template_after_login=&mindestbestellwert=&login=&password=&bpemail=&bpid=&url=&show_wk=&use_search=3&p_back_template=&template=&kna_news=&p_status_scenario=&documentselector=&p_load_area=$ROOT&p_artikelbilder_mode=&p_sortopt=&page=&p_catalog_max_results=10
http://images.conrad.com/m/2000_2999/2200/2220/2223/222377_LB_00_FB.EPS.jpg
http://www2.produktinfo.conrad.com/datenblaetter/200000-224999/222377-da-01-en-E-Motor_Torpedo_850.pdf
http://www2.produktinfo.conrad.com/datenblaetter/200000-224999/222377-an-01-en-E-Motor-Torpedo_850.pdf
Willy
Here is some online info:
http://www1.nl2.conrad.com/scripts/wgate/zcop_nl2/~flNlc3Npb249UDkwX05MX0IyQzpDX0FHQVRFMTE6MDAwMC4wMDY0LmU3YWIyMGRmJn5odHRwX2NvbnRlbnRfY2hhcnNldD1pc28tODg1OS0xJn5TdGF0ZT05NTMyODY0OTg=?~template=PCAT_AREA_S_BROWSE&p_selected_area=%24ROOT&perform_special_action=&glb_user_js=Y&shop=NL2&product_show_id=&p_page_to_display=DirektSearch&~cookies=1&zhmmh_lfo=&zhmmh_area_kz=&s_haupt_kategorie=&p_searchstring=motor+850&p_searchstring_artnr=&r3_matn=&insert_kz=&area_s_url=&area_url=&direkt_aufriss_area=&p_countdown=&p_80=&p_80_category=&p_80_article=&p_next_template_after_login=&mindestbestellwert=&login=&password=&bpemail=&bpid=&url=&show_wk=&use_search=3&p_back_template=&template=&kna_news=&p_status_scenario=&documentselector=&p_load_area=$ROOT&p_artikelbilder_mode=&p_sortopt=&page=&p_catalog_max_results=10
http://images.conrad.com/m/2000_2999/2200/2220/2223/222377_LB_00_FB.EPS.jpg
http://www2.produktinfo.conrad.com/datenblaetter/200000-224999/222377-da-01-en-E-Motor_Torpedo_850.pdf
http://www2.produktinfo.conrad.com/datenblaetter/200000-224999/222377-an-01-en-E-Motor-Torpedo_850.pdf
Willy
Mar 27th 2008
Thanks for the info Willy. I only had time for a quick look but that looks like a good motor. too bad it doesn't have a longer shaft for direct wheel attachment, but that's not an issue for you.
Mar 28th 2008
Hi Tim,
I finaliy finished reading the whole forum...,.
But I`am curious about how it is going with your circuit board?
I`am a electronic engineer and have a far amount of experience in designing and controlling H-bridges .
In my previous hobby project I made my lathe-machine automaic x/y (3*microcontroller <> i2C-bus <> rs232 <> computer <> software).
I`am planning to use this concept in my tennisball machine.
But I first have to do a lot of machenical stuff placing the sensors etc... .
I`am a bit limited in my speare time like all of use, but if you have questions a will try to help.
Willy
I finaliy finished reading the whole forum...,.
But I`am curious about how it is going with your circuit board?
I`am a electronic engineer and have a far amount of experience in designing and controlling H-bridges .
In my previous hobby project I made my lathe-machine automaic x/y (3*microcontroller <> i2C-bus <> rs232 <> computer <> software).
I`am planning to use this concept in my tennisball machine.
But I first have to do a lot of machenical stuff placing the sensors etc... .
I`am a bit limited in my speare time like all of use, but if you have questions a will try to help.
Willy
Mar 28th 2008
Hi Willy,
Thanks for offering to help. I might need it. I've been learning by doing and so far seem successful, but I haven't build any large circuits so far. Perhaps I'll post my draft schematic and layout when I have them to see if you have any suggestions. Glad to know you have some experience there!
Time is very limited for me right now. With usual work and family responsibilities the most I generally get is 3-4 hours each weekend. But right now work is extreemly busy, so I don't have any free time at all. Hopefully that will improve in a few weeks.
-Tim
Thanks for offering to help. I might need it. I've been learning by doing and so far seem successful, but I haven't build any large circuits so far. Perhaps I'll post my draft schematic and layout when I have them to see if you have any suggestions. Glad to know you have some experience there!
Time is very limited for me right now. With usual work and family responsibilities the most I generally get is 3-4 hours each weekend. But right now work is extreemly busy, so I don't have any free time at all. Hopefully that will improve in a few weeks.
-Tim
Mar 29th 2008
Hi all,
I have been reading your forum and thought I'd chime in and try to help out. I've built three very different and very frustrating machines over the past five years. Frustrating primarily for the same reasons you guys have been experiencing, balance and speed of the wheel.The best wheels I've found, considering(1)characteristics which allow the wheel to be turned at high speeds safely(3500rpm)(2)a balance of flexability and ruggedness, doesn't tear up the ball or the wheel too quickly(3)balance, as is, without requiring extreme measures or fancy gadgets or extra expense to have a well balanced wheel(4)cost and availability, are electric wheelchair wheels.These are 8" to 10" wheels which are generally very well made, some more than others,but the bores are in the range of most small motors and are very concentric with the tire bead and the tires are made of a compound that doesn't excessively mark or smudge the ball but is tough enough to last for a good long while.Tires are well balanced and generally have good tread tracking(don't wobble or have lateral runout).Jazzy, electric mobility, etc. no particular favorite they all seem to do equally well and are readily available in most places. Medical suppliers who deal in them tend to change tires and wheels often for patients, discarding a barely used wheel and sometimes tire as well. To get the needed rpm's, power and quick speed recovery out of a common motor I've had best results with Jacuzzi hot tub pump motors, most larger hot tubs have a 3/4 hp-3450 rpm continuous duty motor which are easy to obtain and the wheelchair wheels can be mounted easy enough with perhaps a bushing and a set screw being involved.Well I hope this helps someone, good luck!
I have been reading your forum and thought I'd chime in and try to help out. I've built three very different and very frustrating machines over the past five years. Frustrating primarily for the same reasons you guys have been experiencing, balance and speed of the wheel.The best wheels I've found, considering(1)characteristics which allow the wheel to be turned at high speeds safely(3500rpm)(2)a balance of flexability and ruggedness, doesn't tear up the ball or the wheel too quickly(3)balance, as is, without requiring extreme measures or fancy gadgets or extra expense to have a well balanced wheel(4)cost and availability, are electric wheelchair wheels.These are 8" to 10" wheels which are generally very well made, some more than others,but the bores are in the range of most small motors and are very concentric with the tire bead and the tires are made of a compound that doesn't excessively mark or smudge the ball but is tough enough to last for a good long while.Tires are well balanced and generally have good tread tracking(don't wobble or have lateral runout).Jazzy, electric mobility, etc. no particular favorite they all seem to do equally well and are readily available in most places. Medical suppliers who deal in them tend to change tires and wheels often for patients, discarding a barely used wheel and sometimes tire as well. To get the needed rpm's, power and quick speed recovery out of a common motor I've had best results with Jacuzzi hot tub pump motors, most larger hot tubs have a 3/4 hp-3450 rpm continuous duty motor which are easy to obtain and the wheelchair wheels can be mounted easy enough with perhaps a bushing and a set screw being involved.Well I hope this helps someone, good luck!
Mar 30th 2008
Thank you Octane! That's really helpful to hear. I hadn't heard of anyone considering electric wheelchair wheels, and it's great to have a good option. Were they really that well balanced? I wouldn't have expected that they need to be balanced for their intended use.
I've come across jacuzzi pump motor but for some reason I guess they didn't seem to match what I was looking for. I assume they are AC motors, so you'd have to be able to plug the machine in. Can you vary their speed easily?
Any pictures?
-Tim
I've come across jacuzzi pump motor but for some reason I guess they didn't seem to match what I was looking for. I assume they are AC motors, so you'd have to be able to plug the machine in. Can you vary their speed easily?
Any pictures?
-Tim
Mar 31st 2008
Apr 1st 2008
Hi guys,
I'm hoping to make a cricket bowling machine and stumbled across this forum by chance. I'm a complete duffer at anything like this, so I'm making it all up as I go along.
Excuse my ignorance, but having picked out a motor and a wheel, how on earth do I connect the two directly? Presumably I don't want a wheel with casters in the bore.
Thanks.
I'm hoping to make a cricket bowling machine and stumbled across this forum by chance. I'm a complete duffer at anything like this, so I'm making it all up as I go along.
Excuse my ignorance, but having picked out a motor and a wheel, how on earth do I connect the two directly? Presumably I don't want a wheel with casters in the bore.
Thanks.
Apr 1st 2008
Willy,
Thanks for the pics!! Those wheels are a bit narrower than I had expected. Seems like you've doubled them up at least on one side, which makes it a little more involved but seems to make a nice concave rim.
Thanks for the pics!! Those wheels are a bit narrower than I had expected. Seems like you've doubled them up at least on one side, which makes it a little more involved but seems to make a nice concave rim.
Apr 1st 2008
Tayles,
I originally thought one could just order some standard adaptors to match motors to wheels, but I haven't found them if they exist. The specifics depend of course on your motor and wheel. If you're using a castor wheel, the best would be an adaptor sleeve that fits over the motor shaft and in the hub of the wheel (with any bearings removed). BUT, it seems that generally you have to make or have something like that made. If you're really lucky, you'll have access to a metal lathe to make the part. I've had some success finding a bolt to fit a wheel (e.g., 3/4 inch diam) and drilling out the center to fit the motor shaft.
Maybe others have better solutions, but I haven't found any easy answers. Eventually, I ended up buying wheels and motors that matched without any adaptor needed.
-Tim
I originally thought one could just order some standard adaptors to match motors to wheels, but I haven't found them if they exist. The specifics depend of course on your motor and wheel. If you're using a castor wheel, the best would be an adaptor sleeve that fits over the motor shaft and in the hub of the wheel (with any bearings removed). BUT, it seems that generally you have to make or have something like that made. If you're really lucky, you'll have access to a metal lathe to make the part. I've had some success finding a bolt to fit a wheel (e.g., 3/4 inch diam) and drilling out the center to fit the motor shaft.
Maybe others have better solutions, but I haven't found any easy answers. Eventually, I ended up buying wheels and motors that matched without any adaptor needed.
-Tim
Apr 2nd 2008
Thanks Tim. I feared as much. I don't have access to a lathe, so I was looking for some kind of ready-made adapter - something like this: http://www.maplin.co.uk/Module.aspx?ModuleNo=43523&criteria=ADAPT&doy=2m4
Unfortunately, this particular adapter won't be much use because I cannot find a motor with a 6mm shaft that would be suitable. And a wheel with a 8mm bore (this is the width of the thread, I've discovered) would be similarly unsuitable. I would probably have to do as you have done and find matching wheels and motors. Out of interest, what combinations did you go with?
Unfortunately, this particular adapter won't be much use because I cannot find a motor with a 6mm shaft that would be suitable. And a wheel with a 8mm bore (this is the width of the thread, I've discovered) would be similarly unsuitable. I would probably have to do as you have done and find matching wheels and motors. Out of interest, what combinations did you go with?
Apr 2nd 2008
Hi Tayles,
I'm using motors from Protech, and you can find info about them in earlier posts in this thread (sorry I don't have time to repeat it right now).
As for wheels, I'm using replacement wheels from a tennis machine manufacturer. The manufactures can be pretty skiddish about people making their own machines because they want to sell machines, not just wheels. I've heard that the manufacturer of my wheels has since significantly increased their price. I try not to post too many specifics here out of that sensitivity, but you can email me at timwhunt at yahoo dot com.
I'm using motors from Protech, and you can find info about them in earlier posts in this thread (sorry I don't have time to repeat it right now).
As for wheels, I'm using replacement wheels from a tennis machine manufacturer. The manufactures can be pretty skiddish about people making their own machines because they want to sell machines, not just wheels. I've heard that the manufacturer of my wheels has since significantly increased their price. I try not to post too many specifics here out of that sensitivity, but you can email me at timwhunt at yahoo dot com.
Apr 2nd 2008
OK, thanks. I'll have a look back at some earlier posts. I've actually found a wheel and chain for an electric scooter, so I could just mount the motor separately and have it drive the wheel via the chain. That might be a better solution that trying to fix the wheel directly to the motor.
Apr 16th 2008
Hi Tim, all,
The last weekend a had some good progress in remodel my rim and wheels.
So I decided to test the setup at a field near by, took some cone`s to measure the distance.
At 45deg my rig shoot 40meters!
I'am curious what is your experience when playing a spin ball(influence on the distance)?
Also I made some new pic`s: http://picasaweb.google.nl/wieohwiew/Tennis
Willy
The last weekend a had some good progress in remodel my rim and wheels.
So I decided to test the setup at a field near by, took some cone`s to measure the distance.
At 45deg my rig shoot 40meters!
I'am curious what is your experience when playing a spin ball(influence on the distance)?
Also I made some new pic`s: http://picasaweb.google.nl/wieohwiew/Tennis
Willy
Apr 16th 2008
Hi Willy,
Sound good! Thanks for posting the pictures too. Your machine looks quite serious with all that metal and welding!
I once measured the distance, but I can't remember it, and I'm not sure what the angle was. But 40m sounds pretty good!
If you can use a video camera, it would be interesting to see what the ball speed you're getting is. I've done that by estimating how far the ball moved between frames, taken a 60th of a second apart.
I think spin can have a significant impact on distance, at the same ball speed, but I've never taken any measurements. However, since you'll be loosing ball speed by increasing spin, I'm not sure what will produce the longest distance.
This past weekend was the first time in several weeks that I had anytime for working on my machine. I tried experimenting with alternatives to using a carousel, and ultimately didn't find anything that looked promising. I was trying to create a ball holder and shoot/funnel that would allow the balls to come out in single file (through a tube only big enough for one ball at a time) all by gravity without getting stuck. I was amazed and disapointed at how easily the balls can get stuck. Even with a hole wider than twice the balls' diameter at the bottom of a bowl, they managed to get stuck pretty much every time. They have a surprising ability to form little bridges.
So that keeps me working with a carousel, but I'm trying to figure out how I can make one that's more reliable, so fewer holes pass by without getting a ball in them.
Sound good! Thanks for posting the pictures too. Your machine looks quite serious with all that metal and welding!
I once measured the distance, but I can't remember it, and I'm not sure what the angle was. But 40m sounds pretty good!
If you can use a video camera, it would be interesting to see what the ball speed you're getting is. I've done that by estimating how far the ball moved between frames, taken a 60th of a second apart.
I think spin can have a significant impact on distance, at the same ball speed, but I've never taken any measurements. However, since you'll be loosing ball speed by increasing spin, I'm not sure what will produce the longest distance.
This past weekend was the first time in several weeks that I had anytime for working on my machine. I tried experimenting with alternatives to using a carousel, and ultimately didn't find anything that looked promising. I was trying to create a ball holder and shoot/funnel that would allow the balls to come out in single file (through a tube only big enough for one ball at a time) all by gravity without getting stuck. I was amazed and disapointed at how easily the balls can get stuck. Even with a hole wider than twice the balls' diameter at the bottom of a bowl, they managed to get stuck pretty much every time. They have a surprising ability to form little bridges.
So that keeps me working with a carousel, but I'm trying to figure out how I can make one that's more reliable, so fewer holes pass by without getting a ball in them.
Apr 18th 2008
Hi Tim,
I just opened my physics book and if you know the distance and the angle from the ball, you can calculate the begin speed V0 of the ball.
formula: S=Vx*T = (2*(V0^2)*sin(fi)*cos(fi))/g 40m=(2*(V0^2)*sin(45deg)*cos(45deg))/9.8
-> V0=19.79m/s
Is this answer close to answer you get from the camera frames?
To day I have a day off! And planning to mount my metal frame in a wood casing with the x/y axis.
I Keep you posted with pic`s
Willy
I just opened my physics book and if you know the distance and the angle from the ball, you can calculate the begin speed V0 of the ball.
formula: S=Vx*T = (2*(V0^2)*sin(fi)*cos(fi))/g 40m=(2*(V0^2)*sin(45deg)*cos(45deg))/9.8
-> V0=19.79m/s
Is this answer close to answer you get from the camera frames?
To day I have a day off! And planning to mount my metal frame in a wood casing with the x/y axis.
I Keep you posted with pic`s
Willy
Apr 18th 2008
Hi Willy,
19.79m/s = 44.3 miles per hour. I suspect that is low. I've gotten up to 80MPH, and someone else was closer to 100mph. I believe you're in that range if you're throwing balls 40 meters.
I also suspect that physics equation only works where the ball is not slowed by the air. Seems to me that the rate at which a ball slows down would have a signicant impact on the distance and not taking that into account would underestimate the initial speed of the ball. Tennis balls do slow down significantly. I cannot find the link now, but I've seen studies of pros groundstrokes starting around 70+ MPH and slowing to 50ish MPH by the other side of the court. Part of that is due to the bounce, but a lot is just from the air.
Good luck with the building!
-Tim
19.79m/s = 44.3 miles per hour. I suspect that is low. I've gotten up to 80MPH, and someone else was closer to 100mph. I believe you're in that range if you're throwing balls 40 meters.
I also suspect that physics equation only works where the ball is not slowed by the air. Seems to me that the rate at which a ball slows down would have a signicant impact on the distance and not taking that into account would underestimate the initial speed of the ball. Tennis balls do slow down significantly. I cannot find the link now, but I've seen studies of pros groundstrokes starting around 70+ MPH and slowing to 50ish MPH by the other side of the court. Part of that is due to the bounce, but a lot is just from the air.
Good luck with the building!
-Tim
Apr 20th 2008
Oke, I didn`t know that the air resistance had such a in packed on the ball!
I thing I gonna make a movie and look at the frames.
Before you wrote that you have some problems with the carousel. Why are you experimenting with alternatives, are the ball getting stucked frequently?
I curious because my next chalenge is the carousel or some thing like that.
I made some new pic`s!
Willy
I thing I gonna make a movie and look at the frames.
Before you wrote that you have some problems with the carousel. Why are you experimenting with alternatives, are the ball getting stucked frequently?
I curious because my next chalenge is the carousel or some thing like that.
I made some new pic`s!
Willy
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