With the research all done, I started thinking about how I wanted to build my PlotBot. Having looked at the other designs, I found they were either mounted on a wooden frame and then a piece of paper is taped onto the wooden panel, or they draw directly onto a surface like glass or a wall. Given that the aim is just to make something that catches peoples eye, rather than making posters or drawings for people, I think the best course of action would be to use a whiteboard. I can get one reasonably cheaply, and the mounting is pretty much already sorted.
The whiteboard and mountings.
Once I had bought a whiteboard (600mm x 450mm) I started lining up the parts I had as to how I would mount them. I had also bought 2 Pololu 1204 Stepper Motors and an Adafruit Motorshield v2 (AFMSv2). I did have a few concerns with these parts combined together, in that the motors only draw 600mA and the motorshield provides 1.2A per channel, therefore the motors might get a little hot if they start drawing more than they should – but we’ll see how it goes!
Roughly lining up the parts on a sheet of acrylic.
To mount the acrylic sheet to the whiteboard I used two of the mounts supplied with the whiteboard secured on the top of the sheet. These then hook onto the edge of the whiteboard, and the mounts on the side are adjustable to “lock in” the sheet to the sides of the board. Finally I decided to neatly mount the arduino and AFMSv2 in the center of the acrylic sheet.
I picked up two remote control car wheels at a local hobby store, along with 50m of fishing line, which would form the basis for my reels.
I found some nuts in the garage that fitted the inside of the wheel, and used Araldite (metal glue) to fill the gap around the stepper motor shaft hoping that this wouldn’t go wrong.
Araldite’s in, I was a little bit messy dripping it everywhere!
With the luck of the gods, after leaving it 24 hours to cure I was able to punch the stepper motor shaft out of the nut, leaving a nice shaped hole. The advantage of this method being that I can very easily remove the reels and use the steppers in other projects.
Now that I have the reels mounted on the steppers, I was able to complete the main build; mounting the steppers onto the acrylic sheet, and winding the fishing line onto the wheels – happy days!
Tonight was my first time along at the London Arduino Meet Up.
The London Arduino Group is of a similar idea to the Raspberry Pi Jam events that I’ve been to
before. It is a group of people who want to share knowledge about the Arduino platform and start to
innovate across other platforms.
This month we had presentations including hobby electronics, internet controlled LED’s and 3D
Using an Ethernet shield, Christian, put together a set up where he was able to control the status
of an LED in his web browser. This was done on a local network (sorry guys who wanted to take
control of his little light) where he showed two methods of flicking the switch.
The first method he showed off was to use the arduino as a web server and construct the html on it
as well. Then it was a simple matter of connecting to the IP address that was defined on the
arduino and hey-presto it worked.
The second method that he demonstrated was a little more complicated involving node.JS, sockets and other technical jargon that I didn’t catch.
On a similar vein we had Liam demonstrating the use of a TP-Link Wireless N Nano Router (TL-WR702N) to connect an arduino to the internet. He argued that the use of WiFi shields is overly complicated compared to Ethernet shields, as well as being a lot more expensive So if you are willing to have a slightly bigger package then you can connect the Ethernet shield to the nano router and leave that to sort out the complicated subtleties of wireless connections, allowing you to get on with innovating your wireless solution. Another thought is that a nano router is much more versatile than a WiFi shield because it can be plugged into a computer, games console, Raspberry Pi, or any other device that has an Ethernet socket.
In the realm of Hobby Electronics we had Danny, who was plugging his first ever kit robot. Orionrobots.co.uk is his creation and is where he is selling his first his own starter kit robot. In this kit you will find everything that you need to to construct a small chassis with 4 wheels controlled in pairs (left and right) by a L298n dual H-Bridge controller board which is interfaced to an Arduino Uno R3 (provided in the kit). With a easy fit design, you only need a screwdriver to put this kit together making it perfect for anyone who is; unsure with tools, in need for a robot chassis quickly, or just lazy.
The final talk of the evening was from Mark, on behalf of another London Tech Meet-up group, Future Manufacturing, who have a keen interest in 3D printing. They are really keen to see cross collaboration between our two groups on various projects including potentially the Luma Module Interactive Spaceship. The Luma Module is a KickStarter project where they want to build a spaceship that lights up when people interacts with it. This spaceship will then be shipped (no it won’t fly itself) to Nevada for the Burning Man art Festival at the end of August 2013.