Linear Motion & Bread Dispenser

Hello guys,

I'm helping somebody design a bread dispensing system. This is what we have so far: http://www.electricstud.io/bread-dispenser_01.jpg

At the bottom of this box, there is another small box that will shoot outside whenever somebody wants to dispense some bread, and shoot back in when the user takes the bread. My partner and I were thinking of using actuators to move the box back and forth, because they move linearly.

However, as illustrated in the image, if the box moves back in too slowly, the next two bagels drop down as well, which jams the system. I looked into high-speed actuators and discovered there are some that move 300mm/sec, but in demo videos, they don't seem to be all that fast. I was wondering, would those actuators be fast enough, and if not, are there any viable alternatives one of you might be able to suggest?

Thanks.

Rather than have a fast motion you might consider a mechanism to prevent the next bagels falling until the tray has retracted.

What about a servo that either causes the width of the column to narrow (hinged side panel just above the dispenser) or that inserts "claws" through holes in the side panels.

Another possibility is that the dispenser has a top on which the column of bagels sits and the top slides into place as the dispenser slides out?

Would it be possible to push the bottom bagel out through a slot that only permits one bagel to emerge?

...R

Invert the system, use a sprung base to lift the entire column of bagels upwards, dispense from the top.
Arranging the sprung base to be nearly airtight would slow down the speed the column rises and
presumably prevent jamming (gravity is harder to control!).

Such sprung dispensers are commonly used in canteens for storing plates (in a heated dispenser), the
spring is set to match the weight of the plates.

Of course this way round its much harder to add more bagels...

In agreement with MarkT.

At school we toasted bread on a rotating toaster. Might give you some more ideas...

It's not immediately obvious, but you place items in the front, on a conveyor belt type device, which rotates around the inside of the machine, (toasting bread on both sides), before dumping it out beneath. You could do a similar thing, but step the conveyor so it released one item each time.

You'd want to do FIFO delivery, which the plate dispenser does not allow easily, or you could end up with some really stale items.

Also, how would I reverse the actuator? Can I use an H-bridge for that, or do I need to use a shield?

A h-bridge will allow you to drive a motor in both directions.

I would be inclined just to use servos to do all the movements as they are easy to program and easy to install.

...R