Coin ejectors

One of the core components for this project is the ability to contain coins, and dispense the right quantity of coins, of the right type, at the right time.

All of these key features of the coin ejector component.

Initial design

The initial design for the coin ejector had 2 distinct parts:

• A fixed pinion and rack
• An attachable cylinder that could hold coins of the right type

The reasoning for this was that the only part of the design that really needed change was the holding cylinder: its diameter needs to change to accommodate various coin types.

This design proved brittle (it would easyly get disassembled) and turned out to not be actually needed.

A simple parameterized design allowed printing 1 cylinder for each coin diameter, and get done with it.

Dynamic properties of the coin funnel add-on

Another requirement that needed to be addressed was to make the cylinder more accepting of coins that were not falling perfectly into it. A small addition in the shape of a funnel might prove to be very effective, if designed with care.

I decided to create a prototype funnel to better capture coins that fall around the retention cylinder.

Here you can observe the advantages and dynamic properties of using such a device to capture more coins.

No drawbacks, and a much better coin capture rate.

Manufacturing

Manufacturing this piece was also relatively easy and did not require any magic settings. I decided to skip supports for the small screws holes that were going to be used to attach a servo.

Coin Dispenser - proof of concept

And double-ejection proof of concept

Datasheets and Coin reference material

References from Fleur de Coin

Ordered from smallest to largest

In Scope final iteration	Picture	Coin	Dimensions
No ⛔		5 cents	Diameter 16,25 mm Thickness 1,67 mm
No ⛔		2 cents	Diameter 18,75 mm Thickness 1,67 mm
Yes ✅		10 cents	Diameter 19,75 mm Thickness 1,93 mm
No ⛔		5 cents	Diameter 21,25 mm Thickness 1,67 mm
Yes ✅		20 cents	Diameter 22,25 mm Thickness 2,14 mm
Yes ✅		1 EUR	Diameter 23,25 mm Thickness 2,33 mm
Yes ✅		50 cents	Diameter 24,25 mm Thickness 2,38 mm
Yes ✅		2 EUR	Diameter 25,75 mm Thickness 2,20 mm