Index Photo: 
Robot is designed for these contests: 

Nickel-O-Matic is a wooden nickel printing robot designed after the penny arcade machines of the early 1900's.

I had been reading a book about printing with inkjet technology and wanted to build something that used it. Now something like this had been done before with the ping pong ball printer ( The ping pong ball printer was intended as a production machine though and really wasn't intended to be entertaining, although it is. My goal was to come up with something that maximized the entertainment and produced a product for people to take.

There is a video on YouTube now showing Nickel-O-Matic running:

September 13, 2008
Start of the project

I've been thinking about this thing for the last two weeks not, I guess it's time to start. Most of the parts I needed have been ordered. I plan on building the inkjet printing system first. I had planned on driving the inkjet system separate from the movement system. I had planned on using two BS2's, one for each system but ran into issues with the BS2 and the inkjet system. I need 12 IO pins for the inkjet head and 4 more to run a stepper motor. That eats up all 16 IO pins before we event get started. Well I guess I'll switch to a Propeller chip for the inkjet system. The nickel movement system will still use a BS2 from an old CBA robot prototype, I have a few sitting around.

September 25, 2008
First Ink

Today I have the first test of the inkjet system. Seems to be working fine. It's hard to explane the trill of moving an inkjet head by hand over a piece of paper.

I ended up writing some assembler code to do the timing of the inkjet pulses. Each jet of the inkjet head needs to be turned on for 6 micro seconds and I couldn't get the timing right with Propeller Spin.

Some may wonder why I didn't use a Parallax inkjet system kit. There are a few reasons for this. First, they are no longer sold, maybe I could have found one but I'm not sure. Second, I wanted to have complete control over each jet of the head. I have some plans for doing grahics and a few other things. Third, I wanted to see if I could do it and didn't want to spend the money.

October 3, 2008
Subsystems complete
Most of the subsystems are complete at this time. I just need to finish the wiring of the BS2 board and a few of the sensors.

October 5, 2008
Putting it all together
Most of the mechanical systems are done, mounted and wired. I have the nickel feeder to make yet but I want to spend some time working on the programming of the  nickel movement system. Two weeks until iHobby and still close to being on schedule.

October 14, 2008
Last minute deatails
Just a few more last minute details to do. I have the coin maze about done needing only the sensor to trip the start of the run and a door to stop someone putting a second coin in as it runs. It will be done in time for iHobby.

October 18-19, 2008
iHobby Expo
After a slight mess up last night that somehow trashed the eeprom of the Propeller Chip things are working for the show. The robot was a great hit with the young and old alike. Often kids huddled around the bot taking turns putting robot coinage into the slot. We printed and handed out over 300 wooden nickels over the two days. Seeing that it takes about 90 seconds to print one nickel, the Nickel-O-Matic ran for about 7.5 hours during the show. I great success in my book and I'm very happy with the results. A big thanks to all who helped.