I’m no gambler – I don’t like losing money – but if I’m at somewhere with an arcade I’ll get change of 20p to play in Penny Pushers. With such a small amount of money to begin with I rarely get more than a couple of coins dropping before I’m out of money. There is something in the way the coins hover with a whole bunch looking like they’ll fall anytime soon that fascinates me and I really want them to drop. There are quite a few things I’ve spent more time making than using. This won’t be one of them. I’ve sat at it for an hour at a time.

I’ve thought about building one for quite a while. Something I can play with to my heart’s content and not spend money on. I searched the internet about a year before making this one to see if anyone else had built one. To my surprise there was very little information on them. A couple of posts on some web forums and not much else. A few weeks ago I came across a Coin Pusher on instructables. This spurred me into action, I had to have one!

How I made it

I started with a request to friends for lots of 2p’s. My thanks to Daniel and Megan who each gave me £3 worth or 300 2p’s in total!

Much as I should have loved to have a full sized arcade cabinet I wouldn’t have the space to keep it so I settled on a more reasonable desktop sized version. I wanted the size to feel just right and while a CAD model would give a feel for the relative dimensions nothing could replace a physical prototype so I got out the A3 paper. I was pleased with an hour or two’s cutting and folding work. The final model has few differences to the paper model (and the differences there are intentional changes I made to make it feel right). The other advantage of having a model sitting there is that you know how many different pieces of wood you’ll need and roughly what size.

I headed off to Homebase for wood (expecting to pay a hefty sum for not much material, it’s not the cheapest place!) but was pleasantly surprised to find a few pieces thick MDF in the cut off bin which were 50p each. I carried these round the shop paranoid would someone took them. I also got a sheet of thin (3mm) MDF. All the wood (and a thick piece spare) came to £5.

I got home and calculated the final dimensions of the pieces I needed to cut taking into account the thickness of the wood. The internal space of the cabinet is the same as the paper model. All the pieces were cut with a hand saw because I don’t have a circular saw… yet! This took some time and care but I enjoyed the work. I am so used to working with small electronic components and fiddly bits that it was a welcome change to handle these large, non-delicate pieces of wood. It’s my first project with wood and I certainly want to try more, Wooden Binary Adder in particular.

Now, this is my first wood project and I had no idea how to cut out a space inside wood for the door. My (wrong, stupid, bad, rough and time consuming) approach was to use a drill with a hole saw to make as large a whole as possible. I then cut out chunks using my large hand saw. When it came to small fiddly bits I used the saw on my Swiss Army Knife. I now know the correct ways of cutting out a piece from another piece. I shall not bother explaining here as a quick search will be far more enlightening than I could ever be.

I soon had it screwed and glued together with some hinges for the back door. In this state it could have been tested, if I’d had a motor. I did not. I had a look around and settled on this servo from Dealextreme.

I went further on with the build. Starting by cutting out perspex for the front cover and the coin slide.

The motor still hadn’t arrived by this point and I was getting very impatient to test it. I remembered I had a K’nex motor and soon had that in place. It took a couple of goes to get it right and in the end some super glue was needed and one orange K’nex piece snipped.  I also need to sand down the primer and sliding block.

The servo did eventually arrived and I had it modified for continuous in no time at all. I didn’t take any photos of that but it wasn’t anything fancy. Take the servo apart, remove the potentiometer and other electronics and remove a small mechanical stop on the gear wheel with the output shaft. I just wired the motor straight up to the battery pack with a switch. There are ways to modify a servo for continuous rotation and allow for pulses to control direction and speed but for this purpose it’s not necessary, in fact it would just be more parts (like a microcontroller) to go wrong. I did use standard battery holder clip clip so different holders could be connected. I have found three batteries is ideal.

The servo way mounted by routing out a rectangular hole and then screwing it in with the screws provided. I drilled a hole for the wires and hooked up the switch.

The pushing block is connected to the cam by a piece of 3mm MDF with nails at either end. This is quite a messy solution but so far it has been effective. On the servo end I would like to use a bolt but I have yet to find one thin enough. I used a little bit of super glue to keep the nail in place and stick back foam to stop it riding up (not shown in picture).

Deciding how to decorate it took quite some time. I considered designing some graphics on a computer, printing them out and stick them on but my artistic skill isn’t so good. I also decided even a nice design probably would look very good unless printed out and stuck on. In the end I decided to paint it. After an image search the dominate carnival/fairground colours seemed to be red and white stripes. The red paint I used was a £1 sample pot (75ml) of Riding Hood from Wickes.

The lettering on the sides was done using a stencil. The font for “Penny Pusher” was Big Top and “jonathanjamieson.com” was Rockwell Extra Bold (standard font on Windows). I touched up the lettering once the paper stencil was removed using cheap brushes with most of the bristles snipped off so it was a very fine brush. Thanks to my flatmate Douglas for his assistance in the stenciling!

I think that is the build well covered now. I might make CAD plans when I go back to university at the end of the holiday as an exercise in ProEngineer. If I’ve not been clear or you don’t understand something feel free to email me. If you make one following this page then please send me a photo of it! They’re cool things and I’m surprised more people aren’t making them.

Notes and things I feel are important

The playing characteristics of the machine vary greatly depending on how far forwards the pushing block goes on a machine this size. The coins need some space before they’ll stack up.

Even more important is something I’ll call “sweep”. Sweep. Is the displacement of the block from one extreme to the other (ie. furthest forward and furthest back) A long sweep will mean the coins don’t stack up on the pushing block and get pushed off a lot quicker. This means the coins don’t stack up much on the lower platform. In the large arcade machines with a large bottom surface the coins stack up despite the relatively long sweep. I believe they are designed so that coins drop off the block at a much faster rate than drop off the main shelf. This tricks the player into thinking a big pay off is coming sooner than it really is (sorry if that didn’t make much sense, I’m finding it hard to explain what I mean!).

In real machines not all the coins that drop are given to the player. The coins that drop off at the side are siphoned off. This is hardly surprising as they need to make money!

Are they games of skill? Not really. You can time the release of the coin from your hand to maximise the chance of it falling flat and consequently more likely to push a coin off the pushing block.

My pushing block has a squint edge on one side (whoops!). This means that one direction of servo rotation (clockwise for me) is much better than the other. I also used plenty of WD-40 to keep it moving. Be careful though – it can (and did) damage the paint.

A comment from mikegreenhalgh on the MAKE blog

I used to work with these machines, at either side of the ‘bed’ with the coins on is a hole which leads down to the machine’s cashbox. At the front of the bed is an adjustable lip, as the coins get pushed forward they encounter this lip and start bunching up, coins from behind meeting this mass get pushed sideways causing some to drop down the holes at the side of the bed.

The machines profit percentage is adjusted by adjusting the size of the side holes (via sliding plates that make the holes bigger or smaller) and by moving the lip up or down.

At the place where I used to work we would empty the machines every few days and would generally take >£100 out from the cashboxes under the machine(but it was very busy).