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Category Archives: electronics

Heres a home CNC/drawing project with a twist. The drawing machine uses the time it takes for ink to bleed in to blotting paper to create a grayscale image. More information can be found  here along with some other awesome projects like a street art quadracopter and gesture driven drawing machine.

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I am pretty sure that I have posted about this technique before but this is a particularly good example. The waterfall is by far the biggest install of this type I have seen and the lighting really emphasises the lines produced by the falling water.

Another example only this time wrapped into a cylinder:

I learnt so much in the home brew CNC workshop and I am very aware that if I don’t do something with my new found knowledge soon then I will forget most of it. I am a collector of broken junk and in my collection I have an A3 scanner and an A4 scanner. I have decided to turn these deserted and tired old pieces of equipment into a homebrew plotter / engraver (if all goes well.) The first step was to take the Grbl ready Arduino from a previous post and make it control a stepper motor. I have been leant 3 stepper motor drivers to experiment with, the documentation for the drivers can be found here. The A4983 stepper motor driver is a very compact driver perfect for smaller CNC projects. The documentation for the A4983 is very good so it was very easy to connect it up to the Arduino and the stepper motor. The pictures below evidence my setup with the driver running full steps. I have not experimented with micro steps yet but the results are very promising.

The wiring:

mac to arduino - arduino to a stepper motor

Just a few photos and a video from the 3 days of training I took part in which started on Monday the 11th of July. In the 3 days we put together 2 machines; one that was a gantry based plotter and the other was a turn table based scanner. The interesting part was tooling the plotter to pour slip over clay. The pictures below are just a few photo I took over the 3 days. Mat, another from the CNC workshop documented the whole process better than I did, you can find his photos here

Recently I attended a 3 day training session on building home-brew CNC machines which was run by Dave Turtle from the RCA. It was an amazing 3 days and I will post the photos and videos of the results as soon as possible. One of the hurdles that came crashing in on day two was the limitation of running the kit from the parallel port. There really aren’t that many computers these days that still roll out with a parallel port as standard, not to mention my nice shiny mac does not come equipped with a parallel port. I was 100% sure the solution to this problem was the trusty Arduino. There have been many projects where the Arduino has already been used as the heart of a CNC machine, the first that comes to mind is the REPRAP. There is also another CNC project called Contraptor which utilises the Arduino at its heart. The home site for the Contraptor project has a lot of useful information, it was there I came across Grbl.

I tried the RepRap g code interpreter, fiveD but I could not get it to compile for the Arduino (Any tips would be gratefully recieved). I also tried a few other interpreters with varying success: teapot, rsteppercontrol and arduino-gcode-interpreter-new. I really struggled, probably partly due to my lack of understanding when it comes to g-code. I had no success over the three days of training but I did find Grbl though I didn’t have the kit to test it. Grbl seemed like a very simple solution but the main hurdle when it comes to implementing it is that you need to use avrdude to flash it to the Arduino you can’t just send it via usb direct to the Arduino. I have never done this before so I let the Arduino rest for the the remainder of the training with a mind to try it as soon as possible.

Today I started messing around with Flashing Grbl to the Arduino and was caught out by several issues which slowed my progress. There are already several sites with information on how to do this but I found I needed bits from all my sources to get the job done. I thought I would document my process in case anyone else finds it useful.

First off the sites that proved to be most useful:

http://www.sparkfun.com/tutorials/247

http://www.arduino.cc/en/Hacking/Bootloader

http://dank.bengler.no/-/page/show/5471_gettinggrbl

I started by downloading the prebuilt hex files for Grbl here

I then downloaded Crosspack-AVR from here which installs a version of AVRDUDE (used to handle flashing the data to the Arduino)

The Arduino that is going to act as a programmer needs to have the programming firmware uploaded to it. This is a very simple task as it is all built into the Arduino IDE. Open up the Arduino IDE then go to File -> examples -> Arduino ISP then upload the sketch to the Arduino. The Arduino is now fully setup to Flash another Arduino.

The next step was to wire one Arduino to another to use as a programmer. I found the wiring diagram from Sparkfun here and the picture below is my version of the wiring. One thing that sparkfun didn’t explain is that you must disable  auto reset on serial connection. I found out how to do this here. I could not find a cable to suit so unfortunately I had to solder directly to the ISCP headers (not pretty).

Wiring for flashing the arduino

Now all the setup is done it is time to put AVRDUDE to work, on a Mac this is done via terminal.

I found the terminal commands for AVRDUDE on sparkfun here about half way down the page.

command one (make sure the Arduino is ready for grbl):

avrdude -P /dev/tty.usbserial-A9007VP6 -b 19200 -c avrisp -p m328p -v -e -U efuse:w:0x05:m -U hfuse:w:0xD6:m -U lfuse:w:0xFF:m

change the red text for the name of the serial port that your Arduino is plugged into

command two (load Grbl):

avrdude -P /dev/tty.usbserial-A9007VP6 -b 19200 -c avrisp -p m328p -v -e -U flash:w:grbl.hex -U lock:w:0x0F:m

blue text is for the location of the grbl hex file on the computer

Hopefully thats it, Grbl is now installed!

If you want to test that Grbl is working properly the you can download CoolTerm which is a GUI for mac for sending and receiving information on serial ports.

I come from an art/design background but sometimes I wish I had some training as an engineer. So many of my past projects would have benefited by a little extra knowledge. I have bodged rickety frame work from doweling and 2×2 hacked up sheets of metal to make mechanism, all the time thinking there must be a better way. I have often thought how awesome it would be to own a laser cuter so i could bash out prototypes to my hearts content. Unfortunately I don’t have the sort of money that it takes to acquire this sort of equipment. I am slowly getting my knowledge or engineering resource to a higher standard but it is very slow progress. I came across MicroMax today and it looks very interesting so I thought I would paste it up here incase it can help anyone else. The material looks awesome for rapid prototyping small projects that need accurate and strong frameworks. The website can be found here

The video above is a proof of concept for a kinect guitar pedal project I have begun in collaboration with Jem Mackay another technical instructor at UCF. The general plan is to use the kinect controller to trigger as much functionality as possible within the software Logic Mainstage. MainStage is capable of doing some awesome things such as live loop recording, backing track control and the main feature which intend to utilise which is the live guitar effects processing. From the video above I intend to work on the sensitivity of the pedal so that using the pedal feels more tangible. The pedals functionality is pointless if it does not perform fast and accurately enough to fulfil the needs of the live performer. Eventually it might be good to add some sort of visual feedback to show where the pedals are. This could be done using a mini projector to project the pedal boundaries and the function on to the floor where the guitarist is standing.

We were very lucky recently to have Kim Cascone visit UCF.

Wikipedia says it better than I ever could: Kim Cascone

Kim was a very intense and provocative speaker who there was no doubt in my mind had tremendous passion for his work and field of expertise. He seemed to be hyper observant at a level where no detail was left unscrutinised. He took us on journeys through past memories reminiscent of the tiniest details, from the intrusive tones of coins dropping on to the hard sidewalk to noise of the birds agitated and overactive. I was really impressed by his work with World Building. Never before had I thought about the complexities of the sound design behind films. Kim explained what he called scope and focus as key concepts to understanding the situation of the listener. From his explanation my interpretation of these concepts goes as follows:

Focus is a directional aim of attention from the listener on certain points in the environment. The scope is the almost like the circumference around the focus point, the bigger the scope the larger the area where the listener is able to the sounds is. I am sure that my definition is not quite right but the way I imagine this to look visually is almost like a cone protruding away from the listener with the wide end furthest away. as the scope and focus gets larger and less specific the end of the cone becomes larger allowing a lot more sounds to be heard. If the cone’s base becomes smaller then the listener can really focus in on very specific sounds.

I was very interested in the battle that seemed to be persistant in Kim’s work between the auditory field being 3D and the stereo recording which exists only in 2D. Kim used the term ‘grain’ to explain how if done well a stereo 2D signal can be amplified to a 3D experience by the user. Grain follows the listener, past experiences and sensations amplify and reconstruct the 2D signal.

A small blog entry won’t do this man justice so if you ever get the chance to see Kim talk then it is well worth going.

For the last 2-3 months in the corner of my office a project has been slowly growing as bits and pieces ordered have been arriving sporadically from Ebay’s global sellers. finally, this morning I found an hour or two at work in order to make a concerted effort to get everything pieced together so that I could test that the project would work. The video above is a proof of concept for my first attempt at making an frustrated internal reflection touch screen table (FTIR). The theory is simple; FTIR works by shining infra red light into the sides of a sheet of acrylic so that it internally reflects around the inside of the acrylic. Internal reflection continues until something on the surface of the acrylic sheet disturbs the internal reflection and deflects the infra red out of the acrylic and allows an infra camera (bodged web cam) to spot the infra red thus detecting where the object is on the surface of the table. There are 100’s of articles on line about FTIR, all of them more concise and worded better.

http://modin.yuri.at/teaching/TangibleWorkshop/papers/multitouch.pdf

http://en.wikipedia.org/wiki/Multi-touch

http://wiki.nuigroup.com/Multitouch_Technologies

As a first run I am very pleased with the results. Obviously There is still a lot to be done. I need to work on the rear projection surface and what is called a compliant suface between the acrylic and projection surface. The good news from todays experimenting is that i know it works.

I am not usually that interested in the hobbyist modelling world but the attention to detail and the sheer scale of this project is immense. There are parts of the video that almost look like it is tilt shift photography rather than an automated model. The whole project took 7 years and was a bargain at $4.8 million. I love the fact that the people move around and the vehicles have functioning indicators. The beauty is in the detail.

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