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Dreeass
Posts: 42
Joined: Sat Apr 06, 2013 12:05 am
Location: Ghent, Belgium

Motor questions

Wed Jul 03, 2013 12:22 pm

There is a project I got in my head to make something so I don't always have to feed my dog. But to make this, I need to learn about motors. So I got to know a bit about motors and what I wanted the motors to do is the following:

For the part where the dog's grain drops down, I thought a stepper motor would be the best. But how do I make the things that stop the grain from falling down the tube? I have no experience with this and would like to have some help.

The other part is the dog's water, how do I make that drop down or get in his bowl, I have no idea on how to do this. I thought of something like a water cooling with a desktop pc, but is that the best thing to do?
Increase attachment and avatar size limit or use a third party system?

MangoKid
Posts: 53
Joined: Tue Apr 02, 2013 12:24 pm

Re: Motor questions

Mon Jul 08, 2013 1:12 pm

A stepper would work great for dispensing the grain. The best way to control the flow is to use a turbine wheel. Image

This will help control the amount of grain delivered. The down side is that the control over amount of food is limited to the size of the turbine pocket.

For water dispensing it is best to just use an electronic value, solenoid or whatever you want to call it. When you turn this on water will flow through. When its off nothing flows through. They are pretty cheap and you can get them all over the place.

PiGraham
Posts: 3602
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Motor questions

Mon Jul 08, 2013 1:26 pm

Putting a valve on mains water runs a risk of flooding if the valve is opened when it should not be.
Some local regulations apply to any automatic valve system attached to mains water supply (in UK).
A safe option is to get a small water pump, such as a car windscreen washer pump, and pump water from a bottle into the dog's water bowl.

One option for dry food feeding is some form of vibratory feeder. These can be as simple as tray with a friction surface agitated by a motor with an off-centre weight. If the tray is mounted an flexible mounts the dry food will bounce along the tray in a controlled way. It should be possible to have hopper above the tray so that as the tray feeds more dry food falls onto it.

Some other options might be an Archimedes screw, a paddle-wheel / impeller, a conveyor belt, forced air, powered scoop...

GordonTGopher
Posts: 70
Joined: Sat Dec 01, 2012 11:25 am
Location: Letchworth Garden City

Re: Motor questions

Mon Jul 08, 2013 4:58 pm

This (and the linked blog post) may provide some inspiration http://www.raspberrypi.org/archives/3663

Gordon

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RaTTuS
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Location: North West UK

Re: Motor questions

Mon Jul 08, 2013 5:09 pm

PiGraham wrote:...., powered scoop...
it's getting late
I misread that as powered poop ....
/me sighs
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PiGraham
Posts: 3602
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Motor questions

Mon Jul 08, 2013 5:22 pm

I've been thinking about a wet food dispenser.

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