I am a quite a novice when it comes to mechanical stuff.
I want make a simple bill counting machine. The one that doesn't need to detect counterfeit.
I am thinking of using a stepper motor and attaching a L shaped stick (or popsicle sticks) to it to move one paper from a pack of money.
The counter will be the number of revolutions the stepper motor has to spin. Example 360 revs is equivalent to 360 papers.
So this is my plan:
Attach an L shaped stick to the motor.
Let the L shaped stick touch the paper to move one of it.
The pack of paper will be inside a rectangular box that fits the dimension of the bill.
The rectangular box will have a z-axis motor to move the paper pack upwards after a certain number of counts. (I am not quite sure how this is done since i am a novice in mechanical parts)
Your thoughts? Is there any other simple way aside from this?
Cash machines do not use Popsicle sticks to move the money. Printers don't use Popsicle sticks to move the paper. You should look at how they move paper.
You need to account for slippage. Just knowing that you took 360 * however many steps are need to complete one rotation is not well correlated to the number of bills that were in the input tray.
Cash machines actually use an IR laser and IR sensor, and the bill breaks the beam as it is dispensed. The machine counts the number of times the beam is broken to know how much money it has dispensed.
I suspect the business of getting the top sheet of paper (and only the top sheet) to slide off a pile is as much art as science. I have no idea how cheap printers manage it so reliably.
I agree with @PaulS that you need some separate means to count sheets that does not depend on 100% non-slippage. The converse of that is that a sheet may not always be dispensed with the same amount of motor rotation.
I don't immediately see a role for a stepper motor. A cheap DC motor would probably be quite sufficient - that's all Epson uses
Robin2:
I suspect the business of getting the top sheet of paper (and only the top sheet) to slide off a pile is as much art as science. I have no idea how cheap printers manage it so reliably.
...R
Robin, they do it exactly the same way high speed check sorters do it! One or more rubber wheels on a shaft are resting slightly on the paper. When a sheet is required, the shaft rotates the wheel and attempts to make a sheet move into the guiding mechanism. Jams occur when more than one sheet moves.
On high speed sorters, a similar shaft with rubber wheels almost contacts the check on the other side and rotates in the opposite direction. This stops all but one piece of paper from feeding.
Printers and check sorters cause trouble then poorly handled paper is used. When counting paper money, very worn paper (not really paper!) will also not feed properly.
