Thanks for all your comments and tips which are very much appreciated. Your cube is absolutely awesome and I must admit I have already taken inspiration from your constructional web site and video. I actually have a link to you web site from one of my hallway lighting project blogs (end of page 2).
You might be surprised to know that I have already posted some YouTube video's of my progress, one of which is dedicated to wire straightening. I have an accompanying blog which will be posted here on EE Times in the next few days followed shortly after by my blog on the 8x8 panel construction.
Currently I have 5 panels built and the 6th well under way. I have a base PCB to mount the cube on to that I designed then had made professionally.
I have also constructed a test circuit that uses multiplexing to drive the 8x8 panels as a proof of concept. It seems to work quite well and I have successfully test the 5 panels. As yet I haven't sorted the code for PWM though. I will be looking closely at you implementation of PWM which I think uses Bit Angle Modulation.
Once I have the other 3 panels made I will blog the testing and final assembly, before going onto blogging the creation of my control circuitry.
It would be great to keep in touch with a fellow cube builder :-)
Having just gone through the construction of a 8x8x8 RGB LED cube for a senior design lab with a group, I thought I could provide a few tips, mainly on the contruction side of things. The construction of the cube is by far the most time consuming part of the whole thing (It took the four of us working together approx. 80 hours. 2000+ solder joints takes a lot more time than you think). I found that using a drill to straighten out the wire worked the best. If you clamp one end of the wire in a vice and the other in the drill, you can run the drill for about 10-15 seconds while pulling back slighty, and the wire becomes super straight. I was able to do an 108 inch piece of wire at a time, which yielded 6 18inch pieces. The dimensions of my cube are probably bigger than what yours will be because I went with 10mm LEDS as opposed to the 5mm ones that you have, so the spacing is different. I used the HNTE jig method, which worked out very well.
If you are interested in our project, you can see our final design video here. In the video I mispoke and switched the cathode and anode definition, FYI, but the rest of it should be accurate. Let me know if you have any questions, as I'd be happy to answer them.
@Steve: You and I still need to discuss whether or not one of the PCB's I had manufactured for my cube (another blog coming soon) would be suitable for a NeoPixel version.
I'm up to my armpits in alligators fighting fires without a paddle at the moment (i never metaphor I didn't like) -- I'll be working from a hotel in Louisiana next week (I'm going down there with my wife and son to celebrate her birthday because that's where her family lives) -- so let's chat after that when we've posted your next two blogs on the construction of your cube and i have a better idea as to what will be required for mine...
@Steve: I could have stated this a little more clearly. For example, "I used the serrated edge from an offcut piece of Vero board as a comb to spread the led leads out."
I don't think there was a problem with the way you stated it -- it's just when you said "Veroboard" I immediately thought of sticking the LED leads thru the holes ... and my mind went off on the wrong track. As soon as aI saw the video I realized what you meant and I also realized it was a really ingenious solution to the problem.
@Max: Now, you are using regular RGB LEDs, which will involve lots of multiplexing and stuff. I've decided to go with the Adafruit NeoPixel versions of these devices. Each of these LEDs contains its own controller with current limiting resistors and three 8-bit PWM drivers (one per RGB channel).
I have taken delivery of 10 of those Adaruit NeoPixels myself but haven't gotten round to trying them out yet. A cube built with these little beauties would make the programming a little easier with no multiplexing required and no software PWM to write. The downside would be the increased current consumption due to the non multiplexing. The current for a NeoPixel cube if all led's are white could be between 20-30 amps as apposed to just under 4 amps for my cube which will be using multiplexing.
You and I still need to discuss whether or not one of the PCB's I had manufactured for my cube (another blog coming soon) would be suitable for a NeoPixel version.