Creating a small rice dispenser

Hi everyone,

I am trying to build a simple rice dispenser (actually rice, beans and so on). I've seen a few arduino automated cat/dog foods dispenser around. I have no 3d printer at hand so what do you suggest me?

It's my first attempt so there is no need to be perfect.

I though about the cylindrical recipient with a hole on it, which is rotated by a servo. When the hole is downwards, it will let a few grains out of it (it would be perfect it it was just a single grain). I can probably implement this one on my own right now (just a single servo, and that's it?), but it's quantity will be affected by the amount of grains available inside it.

The other approach that I saw was to have a box with a hole on the bottom which is open to a smaller recipient. The smaller recipient is thus filled by default. When we want the rice, we can push the smaller recipient, which would then block the opening of the larger recipient and at the same time eject the smaller recipient's content since there would be no bottom support when the smaller one is moved. In this approach, I don't know how to make a servo push/pull a box (any links?)

I also saw the approach from this guy: http://www.instructables.com/id/Arduino-controled-dog-foodtreat-dispenser/ I don't know if it's possible to build a really smaller recipient version of it and if it wouldn't spill a lot of its content (we can see some spilling in the video).

I will probably try all of them, but any hints are appreciated.

Other suggestions?

How about an Archimedean Screw?

Ben Krasnow on YouTube made a dispensing carousel for various types of food ingredients. I recommend it as an interesting video anyway, but perhaps it will give you an inspiration for your problem.

Are you trying to dispense by volume, by weight, or by individual item? How you go about the process is different for each method. Frankly, I can't imagine how dispensing individual grains of rice or individual beans is going to be useful. So, I'm thinking that filling a container of a known size is what you want, or filling a random container until the weight changes by the right amount.

Ill try the Archimedean Screw first, thanks! Most of Ben Krasnow's videos were related to other materials (not grains), but they might give some insights once I finish a first attempt with it. Thanks everyone, Ill post the results as soon as I have something up and running

Paul, If possible I am trying to dispense an individual item and, if impossible, by volume. The container would be as small as possible, hence the individual item approach, but if not plausible, then I can go with volume (the smallest, the better).

gsilveira: Paul, If possible I am trying to dispense an individual item and, if impossible, by volume. The container would be as small as possible, hence the individual item approach, but if not plausible, then I can go with volume (the smallest, the better).

Individually may be possible as well. You could try to "pick and place" 'm...

If you would use a controllable vacuum plus the right diameter rubber tube, you could pick a single grain out of a container. Next part, move the grain elsewhere, turn off the vacuum and "place" it. In electronics assembly it's used in pick and place machines to pick up components and place 'm on PCBs.

In electronics assembly it's used in pick and place machines to pick up components and place 'm on PCBs.

Quick. I need two cups of rice. How long is this pick and place machine going to take? I'm hungry.

The Archimedean Screw sounds like a really good idea. If youi know the maximum dimensions of your grains/beans you might be able to design the pitch and depth of the screw to dispense items one at a time.

Rice is going to be a real beggar of a problem due to the elongate shape of the grains; you have a major potential problem with jamming.

Consider just how difficult it is to perform this task by hand.

The first thing that comes to mind is one version or another of the gumball dispenser - a vertical or horizontal wheel with cups milled into it either on the edge or the face (or in fact, holes through it) moving against a plate with openings from the feed hopper and to the outlet at alternate positions.

The problem is of course, that if two grains lodge side by side instead of one lengthways, they can jam. Options include detecting this and reversing the mechanism, or using partial cups which can only lift a single grain clear of the level in the bin (as in many or most Lotto selectors).

In general it seems to me that you are going to have to use sensing to detect whether any given actuation has successfully selected one gain (as against jammed with two, or collected none).

For seed planting there are a number of ways that this is done:

A belt: http://www.freepatentsonline.com/6729249.html A plate with cups: http://wannafarm.com/earthway-seeder-fix/ A horizontal plate with fingers: http://planetjr.net/the_new_seeder A wheel with cups: http://www.mechanicaltransplanter.com/seeder.html A non-typical method using a soft wheel: http://www.seedspider.com/metering.html A revolving drum (like the "IH Cyclo"): https://www.google.com/patents/US4148414 The modern method is a vacuum planter: http://www.monosem-inc.com/ms-metering.html

With respect to rice, though, it's never planted in a field from seed so AFAIK there is no specific method for it. But hey I was on a pretty good roll, there.

what you seek is not that hard. but at what speed ?

a gunpowder trickler is a tube that is placed across a funnel so that tube blocks the funnel there is one hole in the tube to allow your grains fall in. then you rotate the tube. it allows grains to enter on each revolution. and the grains bump and push till they are in a line and rolling and in a single file. more grains coming in, means a grain falls out, one at a time.

you can use an opto-interuputer to verify a grain has fallen.

one simple geared dc motor and one opto-interupter.

you can buy a funnel and tubing at home depot.

the lenght of the tube, the angle of it, are really all that will need adjusting..