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Old Jun 29, 2009, 05:00 PM
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How would I do this?

Basically I'm on a quest to create an "Automatic Ball throwing Machine" for our dog; to fire a tennis ball about 50 feet away. My basic design involving electronics requires two discs on individual motors running continuously. I'm fine with creating all the mechanisms, mounting everything etc; my only problem is how I'll be running the electronics.

I have two spare E-savage motors hanging around that I have no use for

http://modelsport.co.uk/?CallFunctio...n&ItemID=27624

which I think would fare nicely for what I'm doing. I won't be needing an ESC or a receiver so with the two bare wire leads of the motors could I have a direct lead to two batteries and a switch. So two low-cost 7.2V Nimh batteries of a high capacity. How much percentage throttle would the motor be running at? Would it be going at full throttle?

I know it won't last all day so how could I convert this to a mains supply?

Sorry I just have no idea about electronics..

Any help would be appreciated,
Edward
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Old Jun 29, 2009, 05:58 PM
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Bonnie Scotland
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With no speed controller the motors would be running at full throttle. However the actual RPM would depend on the mechanical load placed on the motors by your machine. These motors are designed to run at high speed and may only work in your design if going through a gearbox.

Surely part of the fun of having a dog is the interaction with it, not just switching on a machine to throw balls for it.
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Old Jun 29, 2009, 06:18 PM
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This wouldn't be automated yet. It would just be shooting balls away irrespective of whether the dogs brought them back. So you want a bin into which the dogs should drop the ball, a sensor which identifies a correct ball (you don't want the to through branches or other trash in), then an switch to start the loading and throwing mechanism, a mechanism to vary the direction and strength of through and occassionally fake a throw to keep those beast on their toes, and of course a little speaker which will bark approvingly at them if they go and get the ball and drop it into the bin correctly, cat-hiss at them if they are just being a nuiscance. Of course the thing has to be weatherproofed. And while you're at it, don't forget to add a burgler alerm as this may be getting close to the ideal keep the dogs happy so that I don't have to go and walk them machine

Seriously, not a bad idea to try and reuse some motors this way. But I-m also not enough of an electronics expert to help you out. Actually I think most of your problems will be mechanical (sufficient gear ratio not to overload the motors, loading and throwing the balls properly, etc).
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Old Jun 30, 2009, 05:24 AM
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If you look at baseball practice machines there are no motor controllers. Just a small motor continuously spinning a big flywheel which shoots the ball using mass and friction.


Quote:
Originally Posted by Edwong
Basically I'm on a quest to create an "Automatic Ball throwing Machine" for our dog; to fire a tennis ball about 50 feet away. My basic design involving electronics requires two discs on individual motors running continuously. I'm fine with creating all the mechanisms, mounting everything etc; my only problem is how I'll be running the electronics.

I have two spare E-savage motors hanging around that I have no use for

http://modelsport.co.uk/?CallFunctio...n&ItemID=27624

which I think would fare nicely for what I'm doing. I won't be needing an ESC or a receiver so with the two bare wire leads of the motors could I have a direct lead to two batteries and a switch. So two low-cost 7.2V Nimh batteries of a high capacity. How much percentage throttle would the motor be running at? Would it be going at full throttle?

I know it won't last all day so how could I convert this to a mains supply?

Sorry I just have no idea about electronics..

Any help would be appreciated,
Edward
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Old Jun 30, 2009, 09:35 AM
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Quote:
Originally Posted by electrotor
Surely part of the fun of having a dog is the interaction with it, not just switching on a machine to throw balls for it.
Well our dog wants balls throwing 24 hours of the day and unfortunately I can't do that. At the end of the day he usually has excess energy with which he uses to run round the outside table for no reason lol. Of course its not a social replacement for me. Its also cause I think this would be a fun thing to do!

I've already trained my dog to put balls in a bucket (in the past couple days) so shouldn't be hard for him to learn to stick it in a small basket for the machine. I was quite hoping to avoid a gearbox, I have no idea about that either you see

Could anyone point me to a gearbox that would suit this job for that motor?
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Old Jun 30, 2009, 10:05 AM
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neat idea,could be done with a simple timer to detect the ball rolling down a shoot from the basket. I would use an elevator system to lift the ball to 3 or 4 feet and drop it into a couple spinning wheels.(don't want to hit the dog in the face)

if you make this please post video
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Old Jun 30, 2009, 03:54 PM
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Bonnie Scotland
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OK, short of sedating your dog or giving up your entire life to satisfy the animals passion for ball retrieving you should try Googling "ball throwing machine DIY". It will throw up a few solutions by those who have done it already. The ones I looked at seemed rather complex though.
Good luck.

BTW couldn't you train you dog to throw its own balls (if you pardon the expression)?
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Old Jun 30, 2009, 05:44 PM
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http://www.buygodoggo.com/whatis.html
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Old Jun 30, 2009, 05:56 PM
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Jerry needs no help playing with his ball. (2 min 9 sec)


this is dang cool, but probably can't launch it that far. I think the spinning wheels idea would be the easiest and the cheapest mainly because a spring powered mechanism would be far more complicated and poses more risk of the dog getting tangled up or messing around with something. Gas powered would be expensive...

What I think would be the best for this project would be to have the motor set on a timer after I calculate the median amount of time it takes the dog to get the ball back.. or probably more than that. Thats about as far as I'll go electronic wise and for a budget. However that could cause problems with launching it, so a sensor would be far more ideal. I'd put the sensor probably where the dog will be running to because if I'm doing it with the ball and I want more than one ball in the basket then it will just be firing continuously. So the sensor will turn on the motor so as before the ball is dropped in the wheels are spinning so as no launch failure will be possible and won't be overheating the motors by letting them run continuously.

For avoiding any incidents of hitting the dog on launch, I've come up with an idea. You know you see roller coasters, they run on lines, What I plan on is to take 2/3 pieces of wire on the edge of the pipe that will curve the ball so as it launches from a higher point so poor dog doesn't get hit in the face.

For variation of where the ball goes I was thinking of getting one of those model display turntables, which could make it go anywhere. Here is what the design I think is going to be, with some extra notes along side, enjoy.




Edward
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Old Jun 30, 2009, 05:59 PM
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" Though GoDogGo is fun for your dog, it is not a childs toy."

now what would the world be like if we DID make our kids fetch balls

How does that actually launch the balls? Thats really all i'm interested in. It still looks expensive, I will make sure mine comes out cheaper!
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