Opening and Closing a drawer

Hi all,

I'm comfortable writing software, but when it comes to designing hardware mechanisms etc I have very little idea of the options and generally how one would approach different problems.

So I want to do something which seems fairly simple - an Arduino opening/closing a small drawer.

I imagine some kind of motor could push/pull it open/closed, but how can I tell when it's open/closed and turn the motor off?

Then I thought maybe a servo of some kind, as I can just set the position for it to have, but am I just making it more complicated/expensive than it ought to be?

Help, I am such a noob :smiley:

Cheers
J

What distance must the drawer move between open and closed? And how much force is needed to move the drawer?

The choice of mechanism will be heavily influenced by the space available.

Do you want it to be possible to open and close the drawer manually as well as by power?

A micro-switch is one option for identifying when the end-position has been reached. It could also be used to cut power to the motor and I can conceive of a system that does not need any micro-controller.

...R

Does your drawer have safety features that stop it from being completely opened and falling? Do you need to partially open or close the drawer? If so, how will you know?

Please do the mechanical design before trying to automate the process.

Paul

Robin2:
What distance must the drawer move between open and closed? And how much force is needed to move the drawer?

The choice of mechanism will be heavily influenced by the space available.

Do you want it to be possible to open and close the drawer manually as well as by power?

A micro-switch is one option for identifying when the end-position has been reached. It could also be used to cut power to the motor and I can conceive of a system that does not need any micro-controller.

...R

To give some context, I'm attempting to make a primitive microchip cat feeder.

So far I can read the cat's RFID chips, so the next bit was hooking that up to something which opens and closes to allow access to the food. I was trying to think of the simplest way to achieve this and seemed to me that something similar to a drawer which just opens/closes would be the least complicated?

So I imagine it would only need to open 15-20cm, and isn't going to weigh much (I guess 100g max plus the weight of the drawer itself?). As for opening/closing manually, clearly it doesn't need to be secure, but not intended to be opened manually at all.

spectre1989:
To give some context, I'm attempting to make a primitive microchip cat feeder.

Now, why didn't you start with that?

Does it have to be a drawer? Would an Archimedes Screw do it for you? (Like a vending machine).

SteveMann:
Now, why didn't you start with that?

Because I'm an idiot!

SteveMann:
Does it have to be a drawer? Would an Archimedes Screw do it for you? (Like a vending machine).

I'm trying to picture how that would work - do you mean for an actual cat food dispenser? To be clear, the "drawer" idea was for some way of concealing cat A's bowl from cat B etc, I have one particularly greedy cat who will steal from the others given half a chance. Of course, combining something like this with an actual dispenser system would be great too.

A drawer is a bad idea unless you are planning to make some kind of cat trap! I think you would be better with a flimsy flap. Imagine the worse case such as a cat sticking its head in as the drawer closes. A pop-up flap would be simple and not able to dismember a cat. An Archimedes screw would be fine for dry food. Cats are quite clever, persistent and curious so be aware

pmagowan:
A drawer is a bad idea unless you are planning to make some kind of cat trap!

Oh no, you're on to me!

Currently my cats use these which work well youtube

But that kind of mechanism with the flap with a hinge in the middle looked potentially tricky for an amateur tinkerer. Perhaps something like this would be doable

I don't like the mechanism in your second link in Reply #7. I suspect the flaps or the mechanism would break if the cat stands on a flap.

...R